JP2007266325A - Printed-wiring material, and manufacturing method thereof, and manufacturing method of multilayer printed-wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed-wiring material capable of improving press formation properties when forming a multilayer printed-wiring board, enhancing the filling properties of the resin of an adhesive layer between circuits, and machining to the reliable multilayer printed-wiring board. <P>SOLUTION: The printed-wiring board material is formed by providing an adhesive layer 2 on both the surfaces of an insulating base 1, and filling a conductive material 4 into a through-hole 3 that is open on both the surfaces. The thickness of one adhesive layer 2a in the adhesive layers 2 on both the surfaces is made larger than that of the other adhesive layer 2b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printed wiring material used for manufacturing a multilayer printed wiring board for interlayer connection by an interstitial via hole (IVH), and a method for manufacturing the printed wiring material. The present invention relates to a method for manufacturing a multilayer printed wiring board using a material.

  In recent years, electronic devices have become smaller and lighter and electronic circuits have been digitized and increased in speed. A printed wiring board to be mounted on these electronic devices is also required to have a higher density. In particular, semiconductors arranged on a printed wiring board are increasingly increasing in chip size and number of terminals due to increased integration and higher functionality. In fact, the terminal pitch has been narrowed from the conventional 0.5 mm to the current 0.3 mm pitch, and the current printed wiring board has a limit in securing a signal layer that allows one or two pins to pass between the pins. Therefore, the current situation is that the number of layers is increased.

  Under such circumstances, as the most effective means for fanning out the internal circuit to the outside with the configuration of the printed wiring board with a limited number of layers, all layers have an IVH function, and IVH is the thickness direction of the printed wiring board. The design of an all-layer connection type printed wiring board in which signal lines are exposed to the outside by a stacked via arrangement arranged in a straight line is attracting attention and put into practical use. For example, the method for manufacturing a printed wiring board described in Patent Document 1 is a method that can be expected to have excellent mountability by using a cured CCL material for a single unit constituting a multilayer substrate.

  FIG. 3 shows an example of such a construction method. As shown in FIG. 3A, the adhesive layers 2 having the same thickness are laminated on both surfaces of the insulating base material 1 and the molds are released on the surfaces of the adhesive layers 2. After the film 5 is laminated and the through hole 3 is perforated as shown in FIG. 3B, the conductive material 4 is filled into the through hole 3 as shown in FIG. By removing 5, a printed wiring material A ′ as shown in FIG. 3D can be produced. In this printed wiring material A ′, the conductive material 4 filled in the through hole 3 has bumps protruding from the surface of the adhesive layer 2 at both ends thereof by the thickness of the release film 5.

  A multilayer printed wiring board B ′ is manufactured using this printed wiring material A ′. As the inner layer circuit board 7, the one in which the circuit 6 is formed on both surfaces of the insulating substrate 15 is used. As the inner layer circuit board 7, a through hole provided in the insulating substrate 15 as shown in FIG. A double-sided circuit board of the IVH type in which the double-sided circuit 6 filled with the conductive material 17 in 16 and laminated on the insulating substrate 15 with the cured adhesive layer 18 is conductively connected with the conductive material 17 of IVH through the through hole 16. 7 can be used. This inner layer circuit board 7 is formed by heating and pressing the metal foil on both sides of the printed wiring material A ′ shown in FIG. In addition, a circuit formed by processing this metal foil by a lithography method can be used.

Then, as shown in FIG. 3 (e), the printed wiring material A 'is overlaid on both surfaces of the inner circuit board 7, and the metal foil 8 is overlaid on the outer surface of each printed wiring material A'. Thus, each printed wiring material A ′ is bonded to the inner circuit board 7 by the inner adhesive layer 2, and the metal foil 8 is bonded to the outer surface of each printed wiring material A ′ by the outer adhesive layer 2. FIG. f), a multilayer printed wiring board B ′ having a four-layer structure can be obtained. Further, by forming a circuit by processing each metal foil 8 of the outer layer by a lithography method, a multilayer printed wiring board B ′ is obtained. Can be finished. Further, the multilayer printed wiring board B ′ having the four-layer structure is used as the inner layer circuit board 7, and the printed wiring material A ′ and the metal foil 8 are overlapped on both surfaces in the same manner as described above, and the metal foil 8 is heated and pressed. A multilayer printed wiring board B ′ can be produced by forming a circuit.
Japanese Patent No. 3207663

  When the printed wiring material A ′ is laminated on the inner circuit board 7 as described above to produce the multilayer printed wiring board B ′, the circuit 6 is provided on the surface of the inner circuit board 7. Is more convex than the rest. Therefore, when the printed wiring material A is superimposed on the inner layer circuit board 7 and heated and pressed, the pressing pressure is concentrated on the circuit 6 and it is difficult to apply the pressure uniformly to the entire surface. As a result, there is a problem that it is difficult to sufficiently fill the resin of the adhesive layer 2 of the printed wiring material 4 between the circuits 6.

  In particular, when a multilayer printed wiring board B ′ having a stacked via configuration in which IVH is linearly arranged in the thickness direction is manufactured, as shown in FIG. 3E, the through-hole 3 of the printed wiring material A ′ forming IVH and The printed wiring material A ′ is superimposed on the inner layer circuit board 7 so as to coincide with the through hole 16 of the inner layer circuit board 7 in the vertical direction, and the heat and pressure molding is performed. The conductive material 4 filled in the through hole 3 is illustrated in FIG. It protrudes from the surface of the adhesive layer 2 by the thickness of the release film 5 as in 3 (d). During the heat and pressure molding, the pressing pressure is concentrated on the protruding portion of the conductive material 4, and the protruding portion of the conductive material 4 is flattened by the pressing pressure, but as a reaction, there is no conductive material 4. The phenomenon that pressure is hardly applied to the portion appears remarkably, the filling of the adhesive layer 2 between the circuits 6 of the inner circuit board 7 is insufficient, and sufficient curing cannot be obtained, and an insulating layer called “blur” is not obtained. There was a greater risk of the problem of insulation failure due to shortage.

  The present invention has been made in view of the above points, and can improve the press formability when forming a multilayer printed wiring board, and can increase the resin filling property of the adhesive layer between the circuits. It is an object of the present invention to provide a printed wiring material that can be processed into a reliable multilayer printed wiring board, a method for manufacturing the printed wiring material, and a method for manufacturing the multilayer printed wiring board.

  In the printed wiring material according to claim 1 of the present invention, the printed wiring material is formed by providing the adhesive layer 2 on both surfaces of the insulating substrate 1 and filling the through holes 3 opened on both surfaces with the conductive material 4. Of the adhesive layers 2 on both sides, one adhesive layer 2a is formed to be thicker than the other adhesive layer 2b.

  The invention of claim 2 is characterized in that, in claim 1, both end portions of the conductive material 4 protrude from the surface of each adhesive layer 2.

  According to a third aspect of the present invention, in the first or second aspect, the release film 5 is laminated on the surface side of each adhesive layer 2, and the through hole 3 is formed so as to open on the surface of the release film 5. In addition, the conductive material 4 is filled up to the surface of the release film 5 in the through hole 3.

  In the printed wiring material manufacturing method according to claim 4 of the present invention, the adhesive layer 2 having one thickness larger than the other thickness is laminated on both surfaces of the insulating base material 1 and separated from the surface side of each adhesive layer 2. The mold films 5 are laminated, the through holes 3 opened on both sides are formed, and after filling the through holes 3 with the conductive material 4, each release film 5 is peeled off.

  According to a fifth aspect of the present invention, there is provided a multilayer printed wiring board manufacturing method in which the printed wiring material A according to the first aspect is bonded to each surface of an inner circuit board 7 having circuits 6 formed on both sides. The metal foil 8 is overlapped on the surface of the adhesive layer 2b on the thin side of each printed wiring material A, and is laminated by heating and pressing while overlapping on the layer 2a side.

  Since the printed wiring material A is formed so that the thickness of one adhesive layer 2a is larger than the thickness of the other adhesive layer 2b among the adhesive layers 2 on both sides, the printed wiring material A is formed on the thicker adhesive layer. 2a can be applied to the inner layer circuit board 7 by heating and press forming, and the thick adhesive layer 2a can equalize the press pressure and the resin of the adhesive layer 2a is filled between the circuits 6 of the inner layer circuit board 7. Therefore, it is possible to increase the resin filling property of the adhesive layer 2 between the circuits 6 and obtain a highly reliable multilayer printed wiring board.

  Hereinafter, the best mode for carrying out the present invention will be described.

  In the printed wiring material A of the present invention, the insulating substrate 1 is not particularly limited, but is reinforced with a woven or non-woven fabric of inorganic fibers such as paper and aramid (aromatic polyamide) and organic fibers and glass fibers. An unclad plate obtained by impregnating and drying a thermosetting resin such as an epoxy resin on a material and then heating and pressing the material can be used.

  In laminating the adhesive layer 2 and the release film 5 on both surfaces of the insulating substrate 1, the adhesive layer 2 is formed on one surface of the release film 5 as shown in FIGS. This can be done by adhering them to both sides of 1 on the side of the adhesive layer 2. Although it does not specifically limit as this contact bonding layer 2, For example, thermosetting resins, such as an epoxy resin and a polyimide resin, can be used. The thermosetting resin constituting the adhesive layer 2 is in a semi-cured state, melts by heating, and exhibits adhesiveness. Further, as the release film 5, a thermoplastic resin film such as a polyester film can be used.

  Here, in the present invention, two types of adhesive layers 2a and 2b having different thicknesses are used as the adhesive layer 2 as shown in FIGS. 2 (a) and 2 (b), and an insulating substrate is used as shown in FIG. 2 (c). The thickness of the adhesive layer 2a laminated on one side of 1 and the thickness of the adhesive layer 2b laminated on the other side are different.

  After laminating the adhesive layers 2a and 2b and the release films 5 and 5 on both surfaces of the insulating base material 1 in this way, the insulating base material 1, the adhesive layers 2a and 2b, and the release film as shown in FIG. The through-holes 3 extending over 5 and 5 are formed. The through hole 3 can be formed by laser processing, drilling, or the like.

  Next, as shown in FIG. 2E, the through hole 3 is filled with a conductive material 4. As the conductive material 4, a conductive paste can be used. Then, after filling the through hole 3 with the conductive material 4, the release film 5 is peeled off from the surfaces of the adhesive layers 2a and 2b, thereby obtaining the printed wiring material A as shown in FIG. It is something that can be done. In this printed wiring material A, both end portions of the conductive material 4 formed in a columnar shape in the through hole 3 protrude from the surfaces of the adhesive layers 2a and 2b by the thickness of the peeled release film 5. Become.

  In producing the multilayer printed wiring board B using the printed wiring material A, the printed wiring is provided on both surfaces of the inner circuit board 7 in which the circuit 6 is formed on both surfaces of the insulating substrate 15 as shown in FIG. The material A is stacked, and further, a metal foil 8 such as a copper foil is stacked outside each printed wiring material A. At this time, each printed wiring material A is stacked on the inner layer circuit board 7 on the side of the thick adhesive layer 2a, and the metal foil 8 is stacked on the outer surface of the thin adhesive layer 2b of each printed wiring material A. It is. Further, the printed wiring material A is overlapped with the conductive material 4 being aligned with the position of the circuit 6 of the inner layer circuit board 7.

  Here, as the inner layer circuit board 7, a printed wiring material A ′ having the same thickness of the adhesive layers 2 on both sides as shown in FIG. 3D is used, and copper foil or the like is used on both sides of the printed wiring material A ′. By stacking the metal foils and heating and pressing, the metal foil is pasted in a state of being in close contact with the conductive material 17 filled in the through-holes 16, and this metal foil is processed by a lithography method to form the circuit 6. Can be used. In the inner layer circuit board 7 manufactured as described above, the circuits 6 on both sides are conductively connected by the IVH conductive material 17 formed by the through holes 16.

  In this state where the printed wiring material A and the metal foil 8 are overlapped on both surfaces of the inner layer circuit board 7, by heating and pressing this, each adhesive layer 2a of the printed wiring material A is melted and cured, The printed wiring material A can be laminated and bonded to both surfaces of the inner layer circuit board 7, and each adhesive layer 2 b of the printed wiring material A is melted and cured, and a metal foil 8 is laminated on each outer surface of the printed wiring material A. The multilayer printed wiring board B as shown in FIG. 1B can be obtained.

  Here, as described above, since the adhesive layer 2a of the printed wiring material A on the side to be overlaid on the inner layer circuit board 7 is formed thick, the printed wiring material A is layered on the inner layer circuit board 7 and is heated and pressed. At this time, even if the circuit 6 protrudes from the surface of the inner circuit board 7 or the conductive material 4 protrudes from the printed wiring material A, the space between these protruding portions is filled with the resin of the adhesive layer 2a. Can be molded with a uniform pressing pressure, can improve the press moldability, and can improve the resin filling property of the adhesive layer 2a between the circuits 6, and highly reliable multilayer printed wiring The board B can be obtained. The thickness of the adhesive layer 2a is desirably thicker than the thickness of the circuit 6 in order to ensure the filling of the inner layer circuit board 7 between the circuits 6, and is preferably 20 μm or more. However, if the thickness of the adhesive layer 2a is too thick, the overall thickness of the multilayer printed wiring board B becomes thick, which is contrary to the increase in density as a board space, so the thickness of the adhesive layer 2a is 20 to 50 μm. The range of is preferable. Of course, it is not limited to this thickness.

  On the other hand, the thin adhesive layer 2b on the outer side of the printed wiring material A only needs to secure a thickness capable of bonding the metal foil 8 with high strength. However, the thickness of the metal foil 8 on the mat surface of the mat surface (anchor portion) needs to be thick enough to be bonded, and the metal foil 8 has a mat surface on the mat surface of about 1 to 5 μm. The thickness is desirably 5 μm or more. If the thickness of the adhesive layer 2b is too thick, the overall thickness of the multilayer printed wiring board B becomes thick. Therefore, the thickness of the adhesive layer 2b is preferably in the range of 5 to 20 μm. Of course, it is not limited to this thickness.

  In the multilayer printed wiring board B produced as shown in FIG. 1B, the outer layer metal foils 8 are processed by the lithography method to form the outer layer circuit 20 as shown in FIG. 1C. It can be finished as a multilayer printed wiring board B having a four-layer circuit configuration. In this multilayer printed wiring board B, the inner layer circuit 6 and the outer layer circuit 20 can be conductively connected by IVH conductive materials 4 and 17 formed by the through holes 3 and 16, Further, this IVH can be formed in a stacked via structure that is linearly arranged in the thickness direction. Further, the multilayer printed wiring board B having the four-layer circuit configuration is used as the inner layer circuit board 7, and the printed wiring material A and the metal foil 8 are overlapped on both surfaces in the same manner as in FIG. Further, by processing the metal foil 8 by lithography to form a circuit, a multilayer printed wiring board B can be produced. By repeating this process, any multilayer printed wiring board can be produced. B can be produced.

  In the above embodiment, the inner layer circuit board 7 is formed by electrically connecting the circuits 6 on both sides with the conductive material 17 filled in the through-holes 16 forming IVH. It is not limited to the circuit board 7. For example, in order to form a stacked via structure, if a metal film such as copper is formed on the through hole, cover the normal through hole substrate with epoxy resin and then cover plating. After applying laser processing from one side of the coated substrate or double-sided copper-clad laminate to the opposite copper foil surface, filling plating was performed by electroplating, and bumps were printed on the circuit formed substrate or copper foil After that, the board with the inner layer connection function copper-clad laminate with the inner layer connection function obtained by passing through the prepreg and pressing with copper foil, glass cloth prepreg with a cover film, aramid prepreg, thermosetting resin were arranged Insulating substrates, etc., such as drilling, filling with metal paste, circuit board-formed copper-clad laminate with inner layer connection function obtained by pressing with copper foil after peeling the cover film, etc. It can be used for. Further, a multilayered printed wiring board, a printed wiring board having no through-hole function, or the like may be used.

  Next, the present invention will be specifically described with reference to examples.

Example 1
By using a polyester film having a thickness of about 12 μm as the release film 5, a varnish of epoxy resin having heat resistance equivalent to FR-4 is applied to one side of the release film 5 by a coater method and dried, whereby the adhesive layer 2 Formed. At this time, an adhesive layer 2b having a coating thickness of 10 μm and an adhesive layer 2a having a coating thickness of 30 μm were formed (see FIGS. 2A and 2B).

  Next, using an unclad plate of FR-4 with a thickness of 0.06 mm as the insulating base material 1, using a vacuum laminator, release with an adhesive layer 2 under vacuum at a temperature and pressure of 80 ° C. and 0.1 MPa. Film 5 was laminated on both sides of insulating substrate 1. At this time, an adhesive layer 2a having a thickness of 35 μm was laminated on one side of the insulating substrate 1, and an adhesive layer 2b having a thickness of 15 μm was laminated on the other side (see FIG. 2C).

  After the release film 5 and the adhesives 2a and 2b were laminated in this way, through holes 3 having a hole diameter of about 150 μm were formed by drilling at predetermined locations (see FIG. 2 (d)).

  Next, this base material in which the through hole 3 is formed is placed on a table of a printing machine, and the conductive paste 4 is printed from the release film 5, whereby the conductive material 4 made of the conductive paste is formed in the through hole 3. (FIG. 2 (e)). As the conductive paste, a paste containing spherical silver powder having an average particle diameter of 2 μm as a conductive filler and a thermosetting resin as a binder was used.

  Thereafter, the release film 5 was peeled off to obtain a printed wiring material A (FIG. 2 (f)).

  On the other hand, as the inner layer circuit board 7, the release film 5 with the 10 μm adhesive layer 2 of FIG. 2A is stretched on both sides of the FR4 unclad plate, forming the through holes 16, filling with the conductive material 17, After the release film was peeled in the same manner as above, a copper foil having a thickness of 18 μm was laminated on both sides and heated and pressed to form a circuit 6 on both sides by processing the copper foil by a photolithographic method. What was obtained was used. Then, the printed wiring material A is overlapped on both sides of the inner layer circuit board 7 on the side of the adhesive layer 2a having a thickness of 30 μm while aligning IVH, and further the thickness of 18 μm on the side of the adhesive layer 2b having a thickness of 10 μm. The metal foil 8 which consists of copper foil was piled up (refer Fig.1 (a)).

A multilayer printed wiring board B was obtained by press-molding the assembly assembled in this configuration for 100 minutes under vacuum at 180 ° C. and 3.9 MPa (40 kgf / cm ² ) (FIG. 1 ( b))
Thereafter, the circuit 20 is formed by patterning the metal foil 8 on both surfaces of the multilayer printed wiring board B by a photolithographic method including dry film resist lamination (DFR), ultraviolet curing, DFR development, etching, and DFR peeling. A multilayer printed wiring board having a four-layer circuit configuration having an inner layer connecting function in all layers was obtained (see FIG. 1C).

(Example 2)
A printed wiring material A was produced in the same manner as in Example 1 except that the thickness of the adhesive layer 2b was set to 15 μm and the thickness of the adhesive layer 2a was set to 25 μm, and a multilayer printed wiring board B was further produced.

(Comparative Example 1)
A printed wiring material A was produced in the same manner as in Example 1 except that the thickness of the adhesive layer 2b was set to 20 μm and the thickness of the adhesive layer 2a was set to 20 μm, and a multilayer printed wiring board B was further produced.

(Comparative Example 2)
A printed wiring material A was produced in the same manner as in Example 1 except that the thickness of the adhesive layer 2b was set to 25 μm and the thickness of the adhesive layer 2a was set to 15 μm, and a multilayer printed wiring board B was further produced.

(Comparative Example 3)
A printed wiring material A was prepared in the same manner as in Example 1 except that the thickness of the adhesive layer 2b was set to 30 μm and the thickness of the adhesive layer 2a was set to 10 μm, and a multilayer printed wiring board B was further prepared.

  Regarding the multilayer printed wiring boards of Examples 1 and 2 and Comparative Examples 1 to 3 obtained as described above, whether or not the adhesive layer 2a between the printed wiring material A and the inner layer circuit board 7 is damaged. In addition, the resistance value per hole of IVH of the interlayer junction was measured. The results are shown in Table 1.

  As shown in Table 1, in each of the examples, no blur was generated in the adhesive layer 2a, and good results were obtained.

An example of embodiment of this invention is shown, (a) thru | or (c) are sectional drawings, respectively. An example of embodiment of this invention is shown, (a) thru | or (f) is sectional drawing, respectively. A conventional example is shown, and (a) to (f) are sectional views.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Adhesive layer 3 Through-hole 4 Conductive material 5 Release film 6 Circuit 7 Inner layer circuit board 8 Metal foil

Claims (5)

  In printed wiring materials that are formed by providing an adhesive layer on both sides of an insulating substrate and filling a through hole that opens on both sides with a conductive material, the thickness of one of the adhesive layers on both sides is bonded to the other. A printed wiring material characterized by being formed thicker than the thickness of the layer.   The printed wiring material according to claim 1, wherein both ends of the conductive material protrude from the surface of each adhesive layer.   A release film is laminated on the surface side of each adhesive layer, and the through hole is formed so as to open on the surface of the release film, and the conductive material reaches the surface of the release film in the through hole. The printed wiring material according to claim 1, wherein the printed wiring material is filled.   An adhesive layer having one thickness larger than the other thickness is laminated on both surfaces of the insulating base material, and a release film is laminated on the surface side of each adhesive layer to form through holes that open on both surfaces. A method for producing a printed wiring material, wherein each release film is peeled after filling a conductive material. The printed wiring material according to any one of claims 1 to 3 is superimposed on each surface of an inner layer circuit board having circuits formed on both sides on the side of a thick adhesive layer, and the thin side of each printed wiring material. A method for producing a multilayer printed wiring board, wherein a metal foil is superimposed on the surface of the adhesive layer, and this is heated and pressed.

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