JP4974516B2 - Multilayer substrate manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer substrate, and more particularly to a method for manufacturing a multilayer substrate that can improve the accuracy of the position of each wiring layer by using a confirmation unit.

  Along with the downsizing and higher functionality of electronic devices, multilayer wiring structures have become mainstream in mounting boards housed therein. An example of a method for manufacturing a multilayer wiring board will be described with reference to FIG. 10 (see Patent Document 1 below).

  First, referring to FIG. 10A, first conductive film 101A and second conductive film 101B are brought into close contact with the front and back surfaces of base material 100 made of an insulating material such as resin.

Next, referring to FIG. 10B, the first wiring layer 102A and the second wiring layer 102B are formed by selectively etching the first conductive film 101A and the second conductive film 101B. Further, the third wiring layer 102C and the fourth wiring layer 102D are stacked with the insulating film 103A interposed therebetween, thereby realizing a multilayer wiring structure as shown in FIG. Here, the connection part 104 is a site | part for electrically connecting each wiring layer.
JP 2003-324263 A

  However, the above-described method has a problem that an error occurs in the position between the wiring layers. Furthermore, there is a problem that it is difficult to form the connection portion 104 for connecting the wiring layers with high accuracy. Today, the demand for miniaturization and high functionality has become very high, and the patterns have become increasingly finer. As a result, the connecting portions that connect the wiring layers and the positional accuracy between the wiring layers are severe. Is required.

  In order to solve the above-described problem, a method has been proposed in which a confirmation portion is provided in the inner wiring layer, and each wiring layer is patterned based on the position of the confirmation portion. However, in this method, it is necessary to partially remove the outer resin layer and the conductive film in order to expose the confirmation portion provided in the inner layer to the outside. Conventionally, in order to expose the confirmation portion provided in the inner layer, the outer conductive film is removed by wet etching, and the outer resin layer is removed by laser. Therefore, many steps are required to expose the confirmation portion provided in the inner layer to the outside, which increases the manufacturing cost of the multilayer substrate.

  The present invention has been made in view of the above-described problems, and a main object of the present invention is to provide a method for manufacturing a multilayer substrate that is low in manufacturing cost and excellent in positional accuracy.

  The present invention provides a step of providing a confirmation portion in an inner wiring layer, a step of laminating a conductive film on the inner wiring layer via an insulating film, a step of recognizing the position of the confirmation portion, and the position of the confirmation portion. And a step of forming an outer wiring layer by patterning the conductive film with respect to a reference, and in the step of recognizing the position of the confirmation portion, the insulating film covering the confirmation portion and The conductive film is removed by a laser, and the exposed position of the confirmation portion is recognized.

  Furthermore, in the method for producing a multilayer substrate according to the present invention, the surface of the conductive film is roughened before the insulating film and the conductive film are removed by a laser.

  Furthermore, in the method for manufacturing a multilayer substrate according to the present invention, in the step of removing the insulating film and the conductive film by the laser, the insulating film and the conductive film in a region wider than the confirmation portion are removed to form a removal region. It is characterized by being.

  Furthermore, in the method for producing a multilayer substrate according to the present invention, the insulating film and the conductive film inside the removal region are removed after removing the insulating film and the conductive film at a peripheral portion of the removal region. To do.

  Furthermore, in the method for producing a multilayer substrate according to the present invention, in the step of removing the insulating film and the conductive film by the laser, a removal portion formed by partially removing the insulating film and the conductive film by the laser. Are continuously provided to form the removal region, and the removal portion is provided closer to the periphery of the removal region than the inside of the removal region.

  Further, in the multilayer substrate manufacturing method of the present invention, the confirmation portion is a confirmation hole formed in the insulating film on which the inner wiring layer is formed, and the insulating material constituting the insulating film is filled in the confirmation hole. The insulating material filled in the confirmation hole is removed by the laser.

  The method for manufacturing a multilayer substrate of the present invention includes a step of providing a confirmation hole penetrating the sheet-like inner layer insulating film, and a step of providing inner layer wiring layers on both main surfaces of the inner layer insulating film based on the confirmation hole. And a step of laminating a conductive film on both main surfaces of the inner layer insulating film via an outer layer insulating film, and a step of forming an outer wiring layer by patterning the conductive film based on the confirmation hole. In the step of forming the outer wiring layer, the outer insulating layer and the conductive film covering the confirmation hole are removed by a laser to expose the confirmation hole, and then the position of the confirmation hole is recognized. And

  Furthermore, in the method for manufacturing a multilayer substrate according to the present invention, the surface of the conductive film is roughened before the conductive film and the conductive film are removed by a laser.

  Furthermore, in the method for producing a multilayer substrate according to the present invention, in the step of removing the outer insulating film and the conductive film by the laser, the outer insulating film and the conductive film in a region wider than the confirmation hole are removed, thereby removing the region. Is formed.

  Furthermore, in the method for manufacturing a multilayer substrate according to the present invention, the outer insulating film and the conductive film inside the removal region are removed after the outer insulating film and the conductive film at the peripheral portion of the removal region are removed. Features.

  Furthermore, in the method for manufacturing a multilayer substrate according to the present invention, the insulating material constituting the insulating film is filled in the confirmation hole, and the insulating material filled in the confirmation hole is removed by the laser.

  Furthermore, in the method for producing a multilayer substrate of the present invention, the outer layer insulating film and the conductive film covering one main surface of the inner layer insulating film are removed by irradiating the laser from one main surface, and further the confirmation The insulating material filled in the holes, and the outer insulating film and the conductive film covering the other main surface of the inner insulating film are removed.

  Furthermore, in the method for producing a multilayer substrate according to the present invention, in the step of removing the outer insulating film and the conductive film by the laser, the outer insulating film and the conductive film are partially removed by the laser. The removal region is formed by continuously providing a removal portion, and the removal portion is provided more densely at the peripheral portion of the removal region than inside the removal region.

  According to the multilayer substrate manufacturing method of the present invention, the outer layer conductive film and the insulating film can be collectively removed by laser processing to expose the confirmation portion provided in the inner layer to the outside. Accordingly, the number of steps required for exposing the confirmation unit to the outside is reduced, and thus the manufacturing cost can be reduced.

  Specifically, in the conventional method of exposing the confirmation portion by etching, a step of depositing an etching resist, a step of exposing the etching resist, a step of developing the etching resist, a step of performing wet etching, and removing the etching resist A process etc. were required. In the present invention, these steps accompanying wet etching are omitted. This contributes to cost reduction.

  Furthermore, since etching for exposing the confirmation portion to the outside is not performed, deformation of the confirmation portion due to etching is prevented, and alignment based on the confirmation portion can be performed accurately.

  A method for producing a multilayer substrate according to the present invention will be described with reference to the drawings. In the multilayer substrate manufacturing method of this embodiment, referring to FIG. 8D and the like, the first wiring layer 18A as the inner wiring layer and the second wiring layer are formed on both main surfaces of the first insulating film 12A as the inner insulating film. A wiring layer 18B is formed. Further, a third wiring layer 18C and a fourth wiring layer 18D, which are outer layer wiring layers, are formed via the second insulating film 12B and the third insulating film 12C, which are outer layer insulating films. Further, when patterning these wiring layers and forming connection portions for connecting the wiring layers, the positional accuracy is improved with reference to the confirmation hole 14 shown in FIG. Furthermore, in this embodiment, the confirmation hole 14 is exposed to the outside by partially removing the conductive film and the insulating film by laser processing. Details will be described below.

  With reference to FIG. 1, the process of forming the confirmation hole 14 in the lamination sheet 10 is demonstrated. FIG. 1A is a plan view of the laminated sheet 10 in this step, and FIGS. 1B to 1F are cross-sectional views of the laminated sheet 10 in each step.

  With reference to FIG. 1 (A) and FIG. 1 (B), the detail of the lamination sheet 10 used for this form is demonstrated. The laminated sheet 10 is obtained by adhering a first conductive film 13A and a second conductive film 13B to both surfaces of a first insulating film 12A serving as a core. As the material of the first insulating film 12A, either a thermoplastic resin or a thermosetting resin is selected. In consideration of thermal conductivity and the like, an inorganic filler is mixed in the resin. In order to improve the overall strength, the first insulating film 12A may include a glass cloth, or a glass cloth in which an inorganic filler is mixed. The thickness of the first insulating film 12A can be about 50 μm.

  As a material for the first conductive film 13A and the second conductive film 13B, a metal mainly composed of copper can be generally used. In this embodiment, the rolled copper foil is employed as the material for the first conductive film 13A and the second conductive film 13B. The thickness of both conductive films may be about 10 μm. Further, both conductive films may be directly coated on the first insulating film 12A by a plating method, a vapor deposition method or a sputtering method, or a metal foil formed by a rolling method or a plating method may be attached.

  Furthermore, with reference to FIG. 1 (A), the detail of the lamination sheet 10 is demonstrated. The laminated sheet 10 is formed with a plurality of units 11 which are regions constituting one multilayer substrate. Here, four units 11 arranged in a matrix are formed on the laminated sheet 10. In the figure, the unit 11 has a rectangular planar shape, but a unit 11 having a polygonal shape such as a pentagon or more or a curved shape may be formed.

  Referring to FIG. 1C, a confirmation hole 14 is provided so as to penetrate the first insulating film 12A, the first conductive film 13A, and the second conductive film 13B. The confirmation hole 14 is used for alignment when patterning each wiring layer formed in a later step. Further, the confirmation hole 14 is also used when forming a connection part for electrical connection between the wiring layers.

  The confirmation hole 14 can be formed by drilling with a drill. Further, after the first conductive film 13A and the second conductive film 13B are partially removed by etching, the exposed first insulating film 12A may be removed by laser to form the confirmation hole 14. Further, the confirmation hole 14 may be formed through the first conductive film 13A, the second conductive film 13B, and the first insulating film 12A by laser processing. The diameter of the confirmation hole 14 formed in this step is, for example, about 0.15 mm.

  In this embodiment, referring to FIG. 1A, a confirmation hole 14 is provided in the peripheral portion of each unit 11. Here, a confirmation hole 14 may be provided for each of the plurality of units 11 arranged in a matrix. For example, when 20 units 11 are exposed at the same time in a later step, the confirmation holes 14 are provided in the periphery of the 20 units 11 as a unit. The confirmation hole 14 is located outside the unit 11.

  Referring to FIG. 1D, the first conductive film 13A is partially removed by wet etching to form an exposed portion 15A where the first insulating film 12A is exposed. Here, an exposed portion 15 </ b> A is formed inside each unit 11. In this step, exposure for wet etching is performed based on the position of the center point of the confirmation hole 14 provided for each unit 11.

  Referring to FIG. 1 (E), through hole 15 is formed by removing first insulating film 12A exposed from exposed portion 15A. The removal of the first insulating film 12A can be performed using a laser. This removal by laser is performed until the surface of the second conductive film 13B is exposed at the bottom of the through hole 15. As the laser used here, a carbon dioxide laser is preferable. If there is a residue at the bottom of the through hole 15, wet etching is performed with sodium permanganate or ammonium persulfate to remove this residue.

  In the above description, the through hole 15 is formed by a combination of wet etching and laser processing. However, the through hole 15 is formed through the first conductive film 13A and the first insulating film 12A only by laser processing. It is also possible. By forming the through hole 15 by laser processing, there is an advantage that the process of forming the through hole 15 can be simplified and the manufacturing cost can be reduced. When the through hole 15 is formed by combining wet etching and laser processing, there is an advantage that the positional accuracy of the through hole 15 can be improved. This is because the accuracy of the exposure device used for wet etching is better than that of laser processing.

  With reference to FIG. 1 (F), the 1st connection part 16A which electrically connects the 1st electrically conductive film 13A and the 2nd electrically conductive film 13B is formed by performing a plating process. Specifically, the first connection portion 16A is formed by forming a plating film on the entire surface of the first conductive film 13A including the through hole 15. This plating film is formed by both electroless plating and electrolytic plating. Here, first, a metal film made of Cu having a thickness of about 2 μm is formed on the entire surface of the first conductive film 13A including at least the through holes 15 by electroless plating. As a result, the first conductive film 13A and the second conductive film 13B are electrically connected. Therefore, electrolytic plating is performed again using both the conductive films as electrodes, and Cu having a thickness of about 20 μm is plated. Thereby, the through-hole 15 is filled with Cu, and the first connection portion 16A is formed. If so-called filling plating is performed, it is possible to easily embed only the through holes 15. The plating film is Cu here, but Au, Ag, Pd, or the like may be used as the material of the plating film. Furthermore, a plating film may be formed only on the through hole 15 by performing partial plating using a mask.

  Further, the metal film 17 made of a plating film is also formed on the inner wall of the confirmation hole 14 by this process. The metal film 17 is formed on the inner wall of the confirmation hole 14 with a uniform film thickness. Therefore, although the cross-sectional area of the confirmation hole 14 is reduced due to the adhesion of the metal film 17, a circular planar shape is maintained. In this embodiment, the central point of the confirmation hole 14 is determined by observing several places at the outer peripheral end of the confirmation hole 14, and the alignment is performed with reference to this central point. For this reason, the metal film 17 formed on the inner wall of the confirmation hole 14 does not adversely affect the alignment using the confirmation hole 14.

  Next, with reference to FIG. 2, the process of laminating | stacking the electrically conductive film 13 on the lamination sheet 10 is demonstrated. 2A is a plan view of the laminated sheet 10 in this step, and FIGS. 2B to 2D are cross-sectional views of the laminated sheet 10 at each step.

  Referring to FIG. 2B, the first wiring layer 18A and the second wiring layer 18B are formed by etching the first conductive film 13A and the second conductive film 13B. This is performed by selectively wet-etching each conductive film using an etching resist (etching mask) (not shown). In this step, when the etching resist is exposed, the position of the confirmation hole 14 is recognized and the relative alignment between the laminated sheet 10 and the exposure mask (not shown) is performed. Even if the planar size of the confirmation hole 14 is reduced by forming the metal film 17, the planar shape of the confirmation hole 14 is circular, so that the center point coincides with the previous alignment. Therefore, alignment can be performed with high accuracy.

  Furthermore, in this process, the recognition unit 20 whose position is recognized using X-rays in a later process is also formed by etching. The recognition unit 20 may be a square, a circle, a cross, or the like as long as it can be recognized by the X-ray recognition apparatus. In addition, the position of the recognition unit 20 may be anywhere, but generally the periphery of the unit 11 is preferable.

  Referring to FIG. 2C, next, a conductive film is adhered to both main surfaces of the laminated sheet 10 via an outer insulating film. Specifically, the third conductive film 13C is laminated on the surface of the laminated sheet 10 via the second insulating film 12B. The fourth conductive film 13D is laminated on the back surface of the laminated sheet 10 via the third insulating film 12C. Lamination of the third conductive film 13C and the fourth conductive film 13D can be performed by vacuum pressing. In this step, the confirmation hole 14 is also filled with the resin material constituting the second insulating film 12B and the third insulating film 12C. In this step, a prepreg can be adopted as the second insulating film 12B and the third insulating film 12C. A prepreg is obtained by impregnating a woven fabric made of glass fiber or the like with an epoxy resin or the like.

  Referring to FIG. 2D, next, the guide hole 19 is drilled so as to penetrate the laminated sheet 10. Specifically, referring to FIG. 2A, guide holes 19 are drilled at four locations near the four corners of the laminated sheet 10. The guide hole 19 can be formed by a combination of etching and laser, drilling with a drill, drilling with only a laser, or the like. Here, the alignment for specifying the position of the guide hole 19 is performed by recognizing the position of the confirmation unit 20 shown in FIG. The diameter of the guide hole 19 may be in the range of about several tens of μm to about 2 mm.

  In this step, since the recognition unit 20 is covered with the upper third conductive film 13C, its position cannot be recognized by visible light. Therefore, the position recognition of the recognition unit 20 is performed by irradiating X-rays or the like. By providing the guide hole 19 with reference to the position of the recognition unit 20 that is a part of the first wiring layer 18A, the relative positional accuracy between the first wiring layer 18A and the guide hole 19 can be improved. . The guide hole 19 is used to form a removal region 21 (see FIG. 3C) in a later step. By increasing the position accuracy of the guide hole 19, the position of the removal region 21 becomes accurate, and the confirmation hole 14 can be reliably exposed. In addition, the alignment in this step can be performed based on the outer shape if the outer dimension of the laminated sheet 10 satisfies a predetermined accuracy.

  When this step is completed, the surfaces of the third conductive film 13C and the fourth conductive film 13D are cleaned using an acidic liquid. Further, a CZ process is performed to roughen the surfaces of the third conductive film 13C and the fourth conductive film 13D. By performing this roughening process, it is easy to partially remove the third conductive film 13C and the second insulating film 12B by a laser in a later process. In addition, the surfaces of the third conductive film 13C and the fourth conductive film 13D that are laser processed in a later step may be partially oxidized to produce copper oxide, which may be blackened.

  Referring to FIGS. 3 and 4, next, the confirmation hole 14 for performing alignment is exposed. FIG. 3A is a plan view of the laminated sheet 10 in this step, and FIGS. 3B to 3D are cross-sectional views of the laminated sheet 10 at each step. FIG. 4 is a diagram for explaining the laser processing in this step.

  In this step, after the position of the circular guide hole 19 is recognized, the third conductive film 13C and the second insulating film 12B below the third conductive film 13C are removed by laser processing to form the removal region 21. Then, the confirmation hole 14 is exposed to the outside from the removal region 21. In this step, the third conductive film 13C and the second insulating film 12B are removed by laser processing to expose the confirmation hole 14 without depending on wet etching.

  Referring to FIG. 3B, specifically, the third conductive film 13C and the second conductive film 13C positioned at the periphery of the removal region 21 to be formed and the second are formed using a laser machine with the position of the guide hole 19 as a reference. The insulating film 12B is removed. As described above, first, the peripheral portion of the removal region 21 is removed by laser processing, so that the third conductive film 13C located inside the removal region 21 can be thermally separated from the outer region and removed. Laser processing inside the region 21 is facilitated. In this step, dust generated by the laser 23 removing the third conductive film 13C and the like is immediately sucked by a suction machine (not shown).

  In this step, if the matter of instantaneously irradiating the laser 23 is one shot, the third conductive film 13C and the second insulating film 12B below the third conductive film 13C are removed in the thickness direction by one or two shots. In this embodiment, the third conductive film 13C and the second insulating film 12B are reliably removed by, for example, performing two shots of the laser 23. Further, this adjusts the energy of the laser 23 to prevent the inner first wiring layer 18A from being evaporated by the laser 23 and being penetrated.

  For example, the energy of the first shot is increased (the irradiation time is increased to about 16 μsec), the third conductive film 13C is removed, and the energy of the second shot is decreased (the irradiation time is set to about 10 μsec). The second insulating film 12B is reliably removed (by shortening). Here, the laser irradiation time slightly varies depending on the thickness of the third conductive film 13C and the second insulating film 12B. Further, if the third conductive film 13C and the second insulating film 12B can be reliably removed without penetrating the first wiring layer 18A, the energy of one shot is increased (the irradiation time is lengthened). The third conductive film 13C and the second insulating film 12B may be removed.

  Referring to FIG. 3C, next, by irradiating laser 23, third conductive film 13C and second insulating film 12B inside removal region 21 are removed, and confirmation hole 14 is exposed. In the above process, the third conductive film 13 </ b> C located inside the removal region 21 is thermally separated from the third conductive film 13 </ b> C located outside the removal region 21. Therefore, the energy used for the irradiation of the laser 23 can be reduced (the irradiation time can be shortened), and the third conductive film 13C and the second insulating film 12B inside the removal region 21 can be removed. Here, the number of shots of the laser 23 may be one shot or two shots. By this step, the confirmation hole 14 is exposed to the outside from the removal region.

  In the present embodiment, a solid protection portion 24 is provided in the first wiring layer 18 </ b> A in a region corresponding to the lower portion of the removal region 21. That is, from the lower side of the removal region 21, the protection part 24 made of the first wiring layer 18A is exposed. Further, the protection part 24 is formed wider than the removal region 21. In this way, by providing the protective part 24 made of the first wiring layer 18A, erosion by the laser 23 is stopped at the upper part of the protective part 24, and the first insulating film 12A is prevented from being evaporated by the laser 23. can do. Furthermore, by enlarging the area of the protection part 24 to 2 mm × 2 mm or more, even if the laser 23 is irradiated to the protection part 24, the energy of the laser 23 is dispersed. Therefore, it is suppressed that the laser 23 penetrates the protection part 24.

  Further, in this step, the side wall of the confirmation hole 14 is protected by a metal film 17 made of a plating film. Therefore, even when the laser 23 is irradiated on the side wall of the confirmation hole 14, the laser 23 is reflected by the metal film 17, so that the side wall of the confirmation hole 14 can be prevented from being eroded and deformed.

  Referring to FIG. 3D, after the above process is completed, the fourth conductive film 13D and the third insulating film 12C are partially removed using a laser in the same manner as described above, thereby removing the region 37. And the confirmation hole 14 is exposed from below. By this step, most of the resin material located inside the confirmation hole 14 is removed. Therefore, the position of the confirmation hole 14 can be accurately recognized visually from above and from below.

  Moreover, by irradiating the laser 23 from one main surface, the through hole 14 can be exposed to both the front surface and the back surface of the laminated sheet 10. In this case, the output of the laser 23 is increased, or the laser 23 is irradiated in a concentrated manner near the through hole 14. Thus, for example, referring to FIG. 3C, the third insulating film 12C and the fourth conductive film 13D located below the confirmation hole 14 are removed, and the through hole 14 is exposed to the back surface. Can be made. By doing in this way, the man-hour required in order to expose the confirmation hole 14 is reduced, and there exists an effect which can further reduce the manufacturing cost of a multilayer substrate.

  With reference to FIG. 4, the formation of the removal region 21 by the laser will be described in more detail. 4A is a plan view of the laminated sheet 10, and FIGS. 4B, 4C, and 4D are enlarged plan views of one removal region 21. FIG.

  Referring to FIG. 4B, in this embodiment, a circular region having a diameter D of about 100 μm to 120 μm is irradiated with a laser to remove the third conductive film 13C and the second insulating film 12B. A removal portion 29 is formed. The third conductive film 13 </ b> C and the second insulating film 12 </ b> B inside the removal region 21 are removed by continuously forming the removal portion 29 by laser processing. Such a processing method is generally called trepanning processing. In this step, first, a laser is irradiated along the outer peripheral edge of the removal region 21 to provide a removal portion 29, and the third conductive film 13C and the second insulating film 12B are removed in a line. By doing in this way, the 3rd insulating film 12C located inside the removal area | region 21 can be thermally isolate | separated from the exterior, and the process by a laser can be made easy. Here, the pitch P1 of the removal unit 29 (the distance at which the centers of the adjacent removal units 29 are separated from each other) is, for example, about 50 μm. In this step, the thermal energy given by the laser is dispersed in the conductive film constituting the laminated sheet 10. Therefore, in order to reliably remove the third conductive film 13C and the second insulating film 12B by the laser 23 shown in FIG. 3B, it is necessary to narrow the pitch P1 of the removal portion 29. By this step, the removal portion 29 is continuously formed in a line along the peripheral edge of the removal region 21, and the third conductive film 13C located inside the removal region 21 is thermally separated from the surroundings. .

Referring to FIG. 4C, next, the third conductive film 13C and the second insulating film 12B located inside the removal region 21 are removed, and the confirmation hole 14 is exposed to the outside. Here, similarly to the above, the third conductive film 13 </ b> C and the second insulating film 12 </ b> B are removed by irradiating a laser to form a large number of removal portions 29. The pitch P2 of the removal unit 29 is, for example, about 70 μm, and is longer than the pitch P1 described above. Inside the removal region 21, the third conductive film 13C and the second insulating film 12B can be removed even if the pitch is increased in this way. That is, the amount of laser used is reduced inside the removal region 21. This is because the third conductive film 13C located inside the removal region 21 is thermally separated from the third conductive film 13C located outside the removal region 21 by the above-described process. That is, in the removed region 21, the thermal energy given to the third conductive film 13C by the laser is not dispersed around.

  Further, in this step, the third conductive film 13C and the like located inside the removal region 21 are removed by forming a plurality of rows L1 and L2 each including the removal portion 29 formed in succession. The pitch P3 between the rows L1 and L2 is, for example, about 50 μm, and is narrower than the pitch P2 between the removal portions 29 in each row. By narrowing the pitch P3 between the rows in this way, it is possible to prevent the resin constituting the second insulating film 12B from remaining without being removed between the rows.

  Furthermore, in this embodiment, the removal unit 29 that configures the row L1 and the removal unit 29 that configures the row L2 are arranged in a staggered manner. That is, they are displaced. This also prevents the resin from remaining between the rows L1 and L2.

  Referring to FIG. 4D, the third conductive film 13C and the second insulating film 12B inside the removal region 21 are removed by the above process, and the confirmation hole 14 and the first wiring layer are formed inside the removal region 21. A part of 18A is exposed. Further, if a residue such as resin adheres to the surface of the first wiring layer 18A exposed from the removal region 21, the residue is removed by washing.

As is clear from FIG. 4D and the like, the removal region 21 is formed larger in plan than the confirmation hole 14. For example, the planar size of the confirmation hole 14 is a circle having a diameter of 0.15 mm, whereas the planar size of the removal region 21 is a rectangle of about 2.0 mm square. By making the removal region 21 larger than the confirmation hole 14 in this way, the confirmation hole 14 is positioned inside the removal region 21 even if the position recognition by the guide hole 19 (see FIG. 3B) is made rough. I can do it.

  Further, referring to FIG. 4D, by making the removal region 21 larger than the confirmation hole 14, the position recognition (alignment search) of the confirmation hole 14 can be easily performed. Specifically, when recognizing the position of the confirmation hole 14, an area 38 wider than the confirmation hole 14 is imaged using an imaging unit such as a CCD. And the position of the confirmation hole 14 is recognized using the difference in reflectance between the confirmation hole 14 and the first wiring layer 18 </ b> A inside the region 38. Therefore, if the size of the removal region 21 is slightly larger than that of the confirmation hole 14, the end portion of the removal region 21 is reflected inside the region 38, making it difficult to recognize the position of the confirmation hole 14. There is a fear. Therefore, forming the removal region 21 sufficiently large with respect to the confirmation hole 14 as in this embodiment is very significant for position recognition.

  Furthermore, by increasing the planar size of the removal region 21 to about 2 mm square, it is possible to prevent the etching resist (not shown) used when performing the wet etching of the third conductive film 13C and the like from being damaged. Can do. Specifically, in the etching process for forming the conductive wiring layer, the entire laminated sheet 10 including the removal region 21 is covered with an etching resist made of a dry film. In this embodiment, since the removal region 21 is large in plan, the etching resist is deformed and brought into close contact with the unevenness of the removal region 21 in the step of bringing the etching resist into close contact with the laminated sheet 10. That is, no gap is formed between the etching resist and the removal region 21. Therefore, even in the wet etching process using the etchant, the etching resist is not damaged, so that the etchant is prevented from entering the laminated sheet 10. If the planar size of the removal region 21 is formed as small as about 0.5 mm square, the etching resist may not be able to follow the unevenness of the removal region 21. In this case, since a gap is formed between the etching resist and the removal region 21, it is considered that the etching resist is damaged by the pressure of the etchant in the wet etching process. If the etching resist is damaged, the etchant may enter the laminated sheet 10 and the inner wiring layer may be eroded.

  Next, referring to FIG. 5 and FIG. 6, a second connection portion 16B that penetrates through the second insulating film 12B and connects the first wiring layer 18A and the third conductive film 13C is formed. Specifically, the third conductive film 13C and the second insulating film 12B are partially removed, and a plating film is formed in the removed region, thereby forming the second connection portion 16B. A second connection portion 16B that penetrates the third insulating film 12C is also formed by the same method.

  Specifically, referring to FIG. 5A, first, an etching resist 25 is applied so as to cover the third conductive film 13C. Then, the resist 25 is exposed using the exposure mask 31 of the division exposure machine. The exposure mask 31 has a light shielding pattern 32 on the surface of a transparent substrate such as glass. The shape of the light-shielding pattern 32 has a pattern shape that is reverse to that of the second connection portion 16B to be formed. Here, a positive resist in which a portion not irradiated with the light beam 30 remains is employed as the resist 25. Here, it is also possible to adopt a negative type as the resist 25.

  In this step, the position of the confirmation hole 14 is recognized and the planar position of the exposure mask 31 is adjusted using a CCD camera or the like provided in a not-shown divided exposure machine. The exposure operation in this step may be performed on each unit 11 shown in FIG. 4A or the like, or may be performed collectively on a plurality of units 11 arranged in a matrix.

  The exposure operation described above is also performed on the resist 25 provided so as to cover the lower fourth conductive film 13D. Also at this time, the resist 25 is exposed after the position of the confirmation hole 14 is recognized by the division exposure machine.

  Referring to FIG. 5B, the third conductive film 13C corresponding to the region of the second connection portion 16B to be formed is removed by performing etching through the resist 25 patterned by the exposure process or the like. Is done. Further, the fourth conductive film 13D corresponding to the region of the second connection portion 16B to be formed is also removed.

  With reference to FIG. 5C, details of the alignment using the confirmation hole 14 will be described. In this embodiment, the alignment of the exposure mask 31 is performed with the central portion of the confirmation hole 14 as a reference. Specifically, first, the shape of the confirmation hole 14 is imaged using an imaging means such as a CCD camera. This figure shows a cross section of the confirmation hole 14 in an imaged state. And arbitrary 3 points | pieces are observed in the peripheral part of the confirmation hole 14, and those positions are specified. Here, the first observation point K1, the second observation point K2, and the third observation point K3 are observed, and their planar coordinates are specified. Further, the coordinates of the center point C of the confirmation hole 14 are calculated from the coordinate values of these points by the geometrical theorem. Since the planar shape of the confirmation hole 14 is a circle, the coordinates of the center point C can be easily calculated. Further, since the alignment of the exposure mask 31 is performed with the center point C of the confirmation hole 14 as a reference, exposure with extremely high positional accuracy can be performed.

  Further, the exposure for partially removing the fourth conductive film 13D is also performed with the center position of the confirmation hole 14 as a reference. Therefore, since the resist 25 applied to the front and back surfaces of the laminated sheet 10 is exposed using the same confirmation hole 14, the positional accuracy of the exposed portion is extremely high.

  Next, referring to FIG. 6, the second insulating film 12B exposed from the third conductive film 13C is removed. Further, the third insulating film 12C exposed from the fourth conductive film 13D is also partially removed. 6A is a plan view of the laminated sheet 10, and FIGS. 6B and 6C are cross-sectional views of the laminated sheet 10.

  With reference to FIGS. 6A and 6B, first, relative alignment between the laser irradiator (not shown) and the unit 11 is performed using the position of the confirmation hole 14 as a reference. Next, the laser 23 is irradiated to partially evaporate the second insulating film 12B, thereby forming the through hole 15. The upper surface of the first wiring layer 18A is exposed at the bottom of the through hole 15.

  Further, the third insulating film 12C exposed from the fourth conductive film 13D is removed by laser irradiation in the same manner as described above. The removal of the third insulating film 12C is also performed with reference to the position of the confirmation hole 14.

  In the above description, the through hole 15 is formed by a method combining wet etching and laser irradiation. However, the through hole 15 may be formed only by laser irradiation. In this case, after the position of the confirmation hole 14 is recognized by the laser irradiator, the third conductive film 13C and the second insulating film 12B are collectively removed. According to this method, the man-hour concerning formation of the through-hole 15 can be reduced.

  On the other hand, in order to improve the position accuracy of the through-hole 15, as described above, a technique combining etching and laser irradiation is suitable. This is because the position accuracy of the exposure device for the resist 25 is generally higher than the position accuracy of the laser irradiator. Specifically, the positional accuracy of the resist exposure machine is ± 6 μm, whereas the positional accuracy of the laser irradiator is about ± 10 μm.

  Referring to FIG. 6C, next, a second connection portion 16B made of a plating film is formed in the through hole 15 by performing an electroless plating process and an electrolytic plating process. The details of the plating process in this step are the same as the method described with reference to FIG. In the plating process in this step, a plating film is also formed on the inner wall of the confirmation hole 14. Since the confirmation hole 14 has a cylindrical shape, the cross-sectional shape is reduced by forming a plating film on the inner wall thereof, but the circular cross-sectional shape is maintained. Similarly, a plating film is formed on the inner wall of the guide hole 19.

  Referring to FIG. 7A, next, the third conductive film 13C and the fourth conductive film 13D are etched to form new electrode and wiring patterns. Specifically, after applying the etching resist 25 to the surface of the third conductive film 13C, the resist 25 is patterned by performing exposure using the exposure mask 31. Further, the third conductive film 13C and the fourth conductive film 13D are etched through the patterned resist 25. Again, alignment of the exposure mask 31 and the laminated sheet 10 is performed by recognizing the center point of the confirmation hole 14.

  With reference to FIG. 7 (B), the recognition method of the confirmation hole 14 in this step is basically the same as the recognition method described with reference to FIG. 5 (C). Here, the plating film is formed on the inner wall of the confirmation hole 14, thereby reducing the cross section. In this figure, the peripheral edge of the confirmation hole 14 before the plating film is formed on the inner wall is indicated by a dotted line indicated by V1. And the peripheral part of the confirmation hole 14 after the plating film was formed in the inner wall is shown as the continuous line. By forming a plating film having a uniform thickness on the inner wall of the confirmation hole 14, the circular shape is maintained even if the cross-sectional area of the confirmation hole 14 is reduced. Therefore, also in this step, the position of the center point C is accurately measured by observing three observation points (first observation point, second observation point, and third observation point) around the confirmation hole 14. It becomes possible to do.

  Next, referring to FIG. 8, the wiring layer exposed on the front and back surfaces of the laminated sheet 10 is covered with a solder resist. 8A is a plan view of the laminated sheet 10, and FIGS. 8B to 8D are cross-sectional views of the laminated sheet 10. FIG.

  With reference to FIG. 8B, the third wiring layer 18 </ b> C is formed on the front surface of the laminated sheet 10 and the fourth wiring layer 18 </ b> D is formed on the back surface of the laminated sheet 10 by the etching process described above. Yes.

  Referring to FIG. 8C, a resist 26 is formed so as to cover the third wiring layer 13C and the fourth wiring layer 18D formed on the front surface and the back surface of the laminated sheet 10. The resin forming the resist 26 may be filled in the confirmation hole 14 and the guide hole 19.

  Referring to FIG. 8D, an opening 27 is provided in the resist 26 by evaporation using a laser or a lithography process. The openings 27 may be provided on both sides of the laminated sheet 10 or may be provided only on one side. At the bottom of the opening 27, the third wiring layer 18C or the fourth wiring layer 18D is exposed. The opening 27 can be formed by recognizing the position of the confirmation portion 28 made of the third wiring layer 18C.

  Further, in this step, the opening 27 may be formed with reference to the position of the confirmation hole 14. In this case, after the resist 26 covering the confirmation portion 14 is removed using a laser, the position of the confirmation hole 14 exposed to the outside is used as a reference.

  After the above steps are completed, each unit 11 is separated by dividing the laminated sheet 10 along a dividing line L1 indicated by a one-dot chain line. This separation is performed by cutting the laminated sheet 10 in a region where each wiring layer is not formed using a laser. As a result, it is possible to separate the units 11 while minimizing the occurrence of vibration during cutting. Through the above steps, a multilayer substrate having a multilayer wiring structure is completed. Further, the division of each unit may be performed after the circuit element is fixed to the laminated sheet 10 through the opening 27. The separation can also be performed by processing using a router or pressing.

  Next, with reference to FIG. 9A, a mounting structure (module) using the multilayer substrate 36 manufactured by the above process will be described. A circuit element 33B, which is a semiconductor element, is mounted on the surface of the multilayer substrate 36 via a brazing material 34. Here, the circuit element 33B is mounted face-down, but a fixing structure using a thin metal wire may be employed. The circuit element 33 </ b> A is a passive element such as a chip resistor or a chip capacitor, and is fixed to the multilayer substrate 36 via a brazing material 34. Further, if necessary, a lead or a connector which is a connection means to the outside may be mounted.

  With reference to FIG. 9B, a semiconductor package using a multilayer substrate will be described. Here, the circuit elements 33A and 33B described above are mounted on the surface of the multilayer substrate 36, and the sealing resin 35 is formed on the surface of the multilayer substrate 36 so as to seal each circuit element. Since the multilayer substrate 36 of the present invention is extremely thin, a thin circuit device can be provided by applying such a multilayer substrate to the circuit device. In recent years, the IC itself has a tendency to increase the number of pins to 500 pins and 1000 pins, and the size of the external electrodes tends to be fine and narrow pitch. Therefore, if the multilayer substrate 36 of this embodiment is employed, a circuit module using an IC, a discrete element, a chip capacitor, a chip resistor, etc. can be manufactured.

  In the above-described embodiment, a method for manufacturing a multilayer substrate having four wiring layers has been described. However, the present embodiment can also be applied to a method for manufacturing a multilayer substrate having five or more layers. Also in this case, patterning or the like of each wiring layer is performed based on the position of the confirmation hole 14 provided in the inner insulating film.

  Further, in the above description, the outer wiring layer is laminated on both surfaces of the inner first insulating film 12A. However, the wiring layer is laminated only on one main surface of the first insulating film 12A via the insulating film. It is also possible. Even in such a case, the position of the confirmation hole 14 provided in the first insulating film 12A is used as a reference when forming the second and subsequent wiring layers and connection portions. Further, when recognizing the position of the confirmation hole 14, the insulating film and the conductive film covering the confirmation hole 14 are removed by the laser irradiator. As a result, similar to the above-described embodiment, it is possible to perform alignment with high accuracy while reducing cost.

It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is a top view, (B)-(F) is sectional drawing. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is a top view, (B)-(D) is sectional drawing. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is a top view, (B)-(D) is sectional drawing. It is a figure which shows the manufacturing method of the multilayer board | substrate of this invention, (A) is a top view, (B)-(D) is the enlarged top view. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) and (B) are sectional drawings, (C) is a conceptual diagram which shows the detail of a confirmation hole. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is a top view, (B) and (C) are sectional drawings. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is sectional drawing, (B) is a conceptual diagram. It is a figure which shows the manufacturing method of the multilayer substrate of this invention, (A) is a top view, (B)-(D) is sectional drawing. It is a figure explaining the structure by which the multilayer substrate manufactured by the manufacturing method of the multilayer substrate of this invention was employ | adopted, (A) is sectional drawing, (B) is sectional drawing. It is a figure which shows the manufacturing method of the conventional multilayer substrate, (A)-(C) is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated sheet 11 Unit 12A 1st insulating film 12B 2nd insulating film 12C 3rd insulating film 13A 1st electrically conductive film 13B 2nd electrically conductive film 13C 3rd electrically conductive film 13D 4th electrically conductive film 14 Confirmation hole 15 Through-hole 15A Exposed part 16A 1st connection part 16B 2nd connection part 17 Metal film 18A 1st wiring layer 18B 2nd wiring layer 18C 3rd wiring layer 18D 4th wiring layer 19 Guide hole 20 Recognition part 21 Removal area 23 Laser 24 Protection part 25 Resist 26 Resist 27 Opening portion 28 Confirmation portion 29 Removal portion 30 Light beam 31 Exposure mask 32 Light shielding pattern 33A, 33B Circuit element 34 Brazing material 35 Sealing resin 36 Multilayer substrate 37 Removal region 38 region

Claims (2)

A circular confirmation hole provided in the first insulating film, a metal film made of a plating film formed on the inner wall of the confirmation hole, and the first insulating film corresponding to the front and back of the confirmation hole, from the confirmation hole A protective portion made of the metal film having a large planar size, and a second insulating film and a third insulating film covering the confirmation hole and the protective portion provided on the front surface and the back surface of the first insulating film. And a laminated sheet having a conductive film provided on the second insulating film and a conductive film provided on the third insulating film,
The conductive film provided on the second insulating film corresponding to the peripheral part of the protective part and the second insulating film are irradiated with laser, and the removal part formed by the laser overlaps to form a continuous line. A removal portion formed by forming the first removal region, thermally separating the second removal region located inside the first removal region, and irradiating the second removal region with the laser. In the method of manufacturing the multilayer substrate, the conductive film provided in the second insulating film corresponding to the second removal region and the second insulating film are removed while the confirmation hole and the protection portion are exposed. Yes ,
The protection part is provided to the outside, including the first removal region and the second removal region,
It is formed in a shot shape by the laser when removing the second removal region, rather than a first distance at which the center of the removal portion formed in the shot shape by the laser when removing the first removal region is separated. The second distance at which the center of the removal portion is separated is set longer,
In addition, the removal portion formed in the shot shape is removed by overlapping a plurality of rows, and a third distance that is an interval between the row and the adjacent row is set to be narrower than the second distance,
A method for manufacturing a multilayer substrate, characterized by recognizing an exposed confirmation hole. The method for manufacturing a multilayer substrate according to claim 1, wherein the removal portions formed in the row are arranged in a staggered manner.

Images