JP2004064009A - Manufacturing method for printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a printed circuit board that realizes easy separation of the printed circuit board of multilayer structure becoming a product part from the lamination of resin films formed by adhering a plurality of resin films together by a heating/compressing process. <P>SOLUTION: A plurality of slits 30 are formed so as to surround a product region 60 to be used as a product in each of laminated resin films 23. At this time, the product region 60 is held by an outer frame part via a connection part 31 between slits 30. After the slits are formed, application of heat and compression to a plurality of the resin films 23 laminated adheres the resin films 23 in the heating/compressing process. After the heating/compressing process, the printed circuit board 100 of multilayer structure becoming the product part is obtained by breaking the connection part 31 connecting the product region 60 and the outer frame part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a printed circuit board having a multilayer structure.
[0002]
[Prior art]
Conventionally, as a method of manufacturing a printed circuit board, a resin film having a conductive pattern formed thereon is laminated, and a plurality of resin films are bonded together by heating and pressurizing them to manufacture a printed circuit board having a multilayer structure. Methods are known.
[0003]
For example, according to the method of manufacturing a printed circuit board disclosed in Japanese Patent Application Laid-Open No. 2000-38464, first, conductive patterns are provided on both surfaces of a resin film made of a thermoplastic resin, and the conductive patterns on both surfaces are interlayer-coated with a conductive paste. A plurality of connected double-sided pattern resin films are manufactured. Next, the plurality of double-sided patterned resin films are laminated via a thermoplastic resin film which has been subjected to a process capable of connecting between layers. Then, the laminated double-sided pattern resin film and the resin film are heated to a predetermined temperature and pressurized at a predetermined pressure, so that the thermoplastic resins constituting the respective resin films are softened and adhered.
[0004]
[Problems to be solved by the invention]
When the resin films are adhered to each other by the above-described method for manufacturing a printed circuit board, heat and pressure are applied to the resin films, so that the shapes of the outer edges are likely to be uneven due to softening and flowing of the resin films. For this reason, it is preferable to cut out a product part from the laminate of the resin film and use it as a multilayer substrate as a final product.
[0005]
In addition, when each of the resin films to be laminated has such a size that a plurality of multilayer substrates can be taken out from the laminate in which the resin films are bonded to each other, productivity of the multilayer substrate can be improved. Therefore, it is preferable. Also in this case, a plurality of multilayer substrates need to be cut out from the laminated and bonded resin film.
[0006]
The present invention has been made in view of the above points, and has a multilayer structure of a printed circuit board that can be easily formed as a product part from a resin film laminated body obtained by bonding a plurality of resin films at a time by heat and pressure treatment. It is an object of the present invention to provide a method of manufacturing a printed circuit board capable of separating a printed circuit board.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the method of manufacturing a printed circuit board according to claim 1, wherein a step of preparing a conductor pattern film having a conductor pattern formed on at least one surface of a resin film made of a thermoplastic resin,
In order to electrically connect between conductor patterns located on both surfaces of the conductor pattern film, a via hole is formed in the conductor pattern film, and a filling step of filling the via hole with an interlayer connection material,
A laminating step of laminating a plurality of resin films including the conductor pattern film, and pressing the laminated resin films while heating them with a hot press plate, thereby bonding the resin films to each other to form a multilayer printed circuit board. Heating and pressurizing process,
In each of the laminated resin films, a slit forming step of forming a plurality of slits so as to surround a product region used as a product is performed, and the product region is connected via a connecting portion between the plurality of slits. And is held by the outer frame portion.
[0008]
After a slit is formed in each of the laminated resin films, if heat and pressure are applied to the laminated plural resin films in the heating / pressing step, the resin films are welded to each other. At this time, the slit formed in each resin film has its opening area reduced or sometimes closed due to plastic deformation of the resin film. However, even in the case where the slit is closed, in the case of thermoplastic resin, the portion where the slit is formed once has reduced mechanical properties, and easily closes the slit with a small stress. The resin portions can be separated from each other. In other words, in each of the laminated resin films, by forming a plurality of slits so as to surround the product area, the connection portion that connects the product portion and the outer frame portion after the heating / pressing step can be slightly broken. By simply applying stress, it is possible to easily separate the product part from the outer frame part. Therefore, the product part can be easily taken out from the resin film laminate in which the resin films are bonded to each other by the heating / pressing step.
[0009]
As described in claim 2, in the slit forming step, it is preferable that the plurality of slits are formed such that the positions of the connecting portions are different in the laminated resin films.
[0010]
This is because, when the connecting portion is formed at the same position in each of the laminated resin films, the strength of the connecting portion increases. As described in claim 2, when the positions of the connecting portions are made different in the laminated resin films, the strength of the connecting portions does not increase and the product portion can be easily separated.
[0011]
As described in claim 3, it is preferable that an outer edge frame made of the conductor pattern is formed at an outer edge portion of the laminated resin film. When a plurality of slits are formed in the resin film so as to surround the product part, the rigidity of the resin film itself decreases. Therefore, since the resin film can be reinforced by forming the outer edge frame formed of the conductor pattern on the outer edge portion of the resin film, it is possible to prevent deterioration in workability such as handling and positioning.
[0012]
Further, as described in claim 4, the via hole and the slit are preferably formed by laser processing. According to laser processing, processing of a fine shape can be performed, so that laser processing is suitable for forming a via hole. When the via hole is formed by laser processing and the slit is also formed by laser processing, there is no need to add any special equipment or the like for forming the slit, so that the manufacturing cost does not increase.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method of manufacturing a printed circuit board according to an embodiment of the present invention will be described with reference to the drawings.
[0014]
FIGS. 1A to 1H are cross-sectional views illustrating a schematic manufacturing process of a printed circuit board according to the present embodiment. In FIG. 1A, reference numeral 21 denotes a single-sided conductor pattern film having a conductor pattern 22 formed by etching a conductor foil (copper foil having a thickness of 18 μm in this example) adhered to one surface of a resin film 23 by heating. is there. In this example, a 25-75 μm-thick thermoplastic resin film composed of 65-35% by weight of a polyetheretherketone resin and 35-65% by weight of a polyetherimide resin is used as the resin film 23. The conductor pattern 22a is formed on the outer edge of the resin film 23 as an outer edge frame in order to suppress the thermal expansion and thermal contraction of the thermoplastic resin constituting the resin film 23 while providing rigidity to the resin film 23. Conductor pattern.
[0015]
When the formation of the conductor patterns 22 and 22a is completed as shown in FIG. 1A, then, as shown in FIG. 1B, the surface of the single-sided conductor pattern film 21 on which the conductor patterns 22 and 22a are formed. A protective film 81 is stuck on the surface facing the above using a laminator or the like. The protective film 81 includes a resin layer and a pressure-sensitive adhesive layer coated on the adhesive surface side of the resin layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is a so-called ultraviolet-curable pressure-sensitive adhesive containing an acrylate resin as a main component, and has a property that a cross-linking reaction proceeds when irradiated with ultraviolet rays, and the adhesive force is reduced. .
[0016]
When the sticking of the protective film 81 is completed as shown in FIG. 1 (b), then, as shown in FIG. A via hole 24 having a bottom surface with the pattern 22 as a bottomed via hole is formed. The portion of the conductor pattern 22 that becomes the bottom surface of the via hole 24 is a portion that becomes an electrode at the time of interlayer connection of the conductor pattern 22 described later. The via holes are formed by adjusting the output of the carbon dioxide gas laser, the irradiation time, and the like so that holes are not formed in the conductor pattern 22. At this time, as shown in FIG. 1B, an opening 81a having substantially the same diameter as the via hole 24 is also formed in the protective film 81.
[0017]
An excimer laser or the like can be used for forming the via hole 24 in addition to the carbon dioxide gas laser. A via hole forming method such as drilling other than laser is also possible, but it is preferable to perform drilling with a laser beam because a hole with a fine diameter can be formed and the conductor pattern 22 is hardly damaged.
[0018]
When the formation of the via hole 24 is completed as shown in FIG. 1C, the conductive paste 50 as an interlayer connection material is filled in the via hole 24 as shown in FIG. 1D. The conductive paste 50 is obtained by adding a binder resin or an organic solvent to metal particles such as copper, silver, and tin, and kneading the mixture to form a paste.
[0019]
The conductive paste 50 is printed and filled into the via hole 24 of the single-sided conductor pattern film 21 from the opening 81a of the protection film 81 with the conductor pattern 22 side of the single-sided conductor pattern film 21 facing downward by a screen printing machine using a metal mask. Is done. This is to prevent the conductive paste 50 filled in the via hole 24 from dropping. If the conductive paste 50 has such a viscosity that the conductive paste 50 does not fall, the single-sided conductive pattern film 21 may be oriented such that the conductive pattern 22 side is other than the lower side. In the present embodiment, the via hole 24 is filled with the conductive paste 50 using a screen printing machine. However, other methods using a dispenser or the like are also possible as long as the filling can be reliably performed.
[0020]
When the filling of the conductive paste 50 into the via hole 24 is completed, a slit 30 is formed in the resin film 23 as shown in FIG. As shown in the plan view of the single-sided conductive pattern film 21 in FIG. 2, the slits 30 are formed so as to surround each of a plurality of (four in this embodiment) product areas 60. However, the slit 30 is divided into a plurality of slits so that each product region 60 does not fall off the resin film 23, and a connecting portion 31 connecting the product region 60 and the outer frame portion or the product regions is provided between the slits. Is formed. In FIG. 2, the conductor pattern 22 in the product region 60 is not described.
[0021]
The slit 30 can be formed, for example, by irradiating the resin film 23 with a laser. Further, the slit 30 may be formed by a drill router, a punching process, or the like. However, when a laser is used for forming the via hole 24 shown in FIG. 1C, it is preferable to use a laser also for forming the slit 30. Thereby, it is not necessary to provide a dedicated facility or the like for forming the slit 30.
[0022]
The width of the slit 30 is desirably 1 mm or less, more preferably, the thickness of the resin film 23 or less. As will be described in detail later, the resin film 23 is heated and pressed in a state where a plurality of the resin films 23 are stacked. During the heating and pressurization, the thermoplastic resin forming the resin film 23 softens and flows. At that time, if the width of the slit 30 is large, the thermoplastic resin flows so as to close the slit 30, so that the flow amount of the thermoplastic resin tends to be large. In this case, it is preferable that the width of the slit 30 be narrow, since the possibility of displacement of the conductive pattern 22 formed on the resin film 23 increases.
[0023]
After the slit 30 is formed, ultraviolet rays are irradiated from the protective film 81 side by an ultraviolet lamp (not shown). Thereby, the pressure-sensitive adhesive layer of the protective film 81 is cured, and the adhesive force of the pressure-sensitive adhesive layer is reduced.
[0024]
When the irradiation of the protective film 81 with the ultraviolet rays is completed, the protective film 81 is peeled off from the single-sided conductive pattern film 21. Thus, as shown in FIG. 1F, a single-sided conductive pattern film 21 in which the slit 30 is formed in the resin film 23 and the conductive paste 50 is filled in the via hole 24 is obtained. The formation of the slit 30 may be performed after the protective film 81 is peeled off from the one-sided conductor pattern film 21.
[0025]
Next, as shown in FIG. 1G, a plurality of single-sided conductor pattern films 21 (six in this embodiment) are laminated. At this time, the lower three single-sided conductor pattern films 21 are provided with the conductor patterns 22 and 22a on the lower side, and the upper three single-sided conductor pattern films 21 are provided with the conductor patterns 22 and 22a. The layers are stacked with their sides facing up. In addition, as shown in FIG. 1G, the slits 30 are formed so as to surround the periphery of the product area 60 in all the single-sided conductor pattern films 21 to be laminated.
[0026]
Then, the laminated single-sided conductor pattern film 21 is heated and pressed from both upper and lower surfaces by a heating press (not shown). When specific heating and pressing conditions are exemplified, the pressure is a value in the range of 0.1 to 10 MPa, and the heating temperature is a value in the range of 200 to 350 ° C. Further, the heating and pressurizing time is set to about 10 to 40 minutes.
[0027]
By performing the above-described heating / pressing process, the single-sided conductor pattern films 21 are bonded to each other. That is, the resin films 23 of the single-sided conductor pattern films 21 are integrated by heat fusion. Further, the conductive paste 50 in the via hole 24 is sintered and integrated into a conductive composition 51 by heating and pressing, and the adjacent conductive patterns 22 are interlayer-connected.
[0028]
After the laminated single-sided conductor pattern films 21 are bonded to each other in this manner, a separation step of separating the product region 60 to be a product portion is performed. That is, in the present embodiment, the slits 30 are formed so as to surround the periphery of each product region 60 as described above. When the slits 30 are formed in the resin film 23 made of a thermoplastic resin, mechanical properties of a portion where the slits 30 are formed deteriorate. For this reason, the product region 60 can be easily separated from the outer frame portion and other parts by applying a small stress that can break the product region 60 and the outer frame portion and the connecting portion 31 connecting the product regions 60 to each other after the heating / pressing process. From the product area 60. Then, as shown in FIG. 1H, by separating the product region 60 from the outer frame portion and other product regions 60, a printed circuit board 100 having a multilayer structure as a product is obtained.
[0029]
Here, it is preferable that the connecting portions 31 that connect the product region 60 to the outer frame portion are formed at different positions on each of the laminated single-sided conductor pattern films 21. When the connecting portions 31 are formed at the same position in all the single-sided conductive pattern films 21, the connecting portions 31 are also adhered to each other, so that the rigidity of the connecting portions 31 increases. Therefore, the stress required for separating the product region 60 also increases. Therefore, in order to separate the product region 60 with a little stress, it is effective to make the connecting positions 31 of the single-sided conductor pattern films 21 different from each other. However, it is not necessary to shift the position of the connection part 31 in all the single-sided conductor pattern films 21, and the connection part 31 is broken by changing the position of the connection part 31 for at least a part of the single-sided conductor pattern film 21. Can be reduced.
[0030]
Further, as described above, by forming the slits 30 so as to surround the periphery of each product region 60, an effect of preventing displacement of the laminated single-sided conductor pattern films 21 can be obtained. This will be described below.
[0031]
When the resin film 23 is heated by performing the above-described heating / pressing process, the resin film 23 thermally expands. In addition, when the heating is completed and the temperature is lowered, the material contracts thermally. The amount of thermal expansion and the amount of thermal contraction may be different for each resin film 23. Then, a displacement occurs between the conductive pattern 22 formed on the resin film 23 and the conductive paste 50 as an interlayer connection material, or a stress is generated after welding. This thermal expansion or thermal contraction becomes more conspicuous as the size of the resin film 23 increases.
[0032]
In order to solve such a problem, in the present embodiment, the slit 30 is formed so as to surround the product area 60 in all the single-sided conductor pattern films 21 to be laminated. Can be. Therefore, the amount of thermal expansion and the amount of thermal contraction in each product region 60 can also be reduced. As a result, the displacement of the conductor pattern 22 formed on the resin film 23 is less likely to occur, so that the occurrence of connection failure can be prevented, and the occurrence of stress after welding can be suppressed.
(Other embodiments)
In the embodiment described above, the conductor pattern 22a serving as an outer edge frame is formed at the outer edge of each resin film 23, but the conductor patterns 22a may be connected to each other via a conductive paste. Preferably, the connection is made over substantially the entire circumference of the conductor pattern 22a. Accordingly, the resin in the product region 60 is surrounded by the conductive pattern 22a and the conductive paste, so that the thermal expansion and thermal contraction of the resin film 23 in the product region 60 can be further suppressed.
[0033]
Further, in the above-described embodiment, an example in which four product regions 60 are provided on the single-sided conductive pattern film 21 has been described. However, the number of the product regions is arbitrary, and three or less or five or more product regions are provided. May be.
[0034]
Further, in the above embodiment, a resin film composed of 65 to 35% by weight of a polyetheretherketone resin and 35 to 65% by weight of a polyetherimide resin is used as a resin film as an insulating base material. A film in which a non-conductive filler is filled in a polyetheretherketone resin and a polyetherimide resin may be used, or a thermoplastic resin film of another material (for example, polyethylene naphthalate, polyethylene terephthalate, polyether sulfone, Plastic polyimide, a so-called liquid crystal polymer, etc.) may be used. Any thermoplastic resin film that can be bonded by a heat press and has heat resistance required in a subsequent step such as a soldering step can be suitably used.
[0035]
In the above embodiment, the conductive paste 50 is used as the interlayer connection material. However, the paste may be in the form of particles instead of paste as long as it can be filled in the via holes.
[0036]
Furthermore, in the above-described embodiment, an example in which a printed board having a multilayer structure is formed from the single-sided conductor pattern film 21 has been described. However, a printed board may be formed using a double-sided conductor pattern film. For example, a plurality of double-sided conductor pattern films may be prepared, and these may be laminated via a film in which an interlayer connection material is filled in via holes, or a single-sided conductor pattern film may be provided on both sides of one double-sided conductor pattern film. May be laminated.
[Brief description of the drawings]
1 (a) to 1 (h) are cross-sectional views showing a schematic manufacturing process of a printed circuit board according to an embodiment of the present invention.
FIG. 2 is a plan view showing a configuration of a single-sided conductor pattern film formed in a process of manufacturing the printed circuit board shown in FIG.
[Explanation of symbols]
21 single-sided conductor pattern films 22, 22a, conductor pattern 23 resin film 24 via hole 30 slit 31 connecting portion 50 conductive paste 60 product area 100 printed circuit board

Claims (4)

A step of preparing a conductor pattern film having a conductor pattern formed on at least one surface of a resin film made of a thermoplastic resin,
In order to electrically connect between conductor patterns located on both surfaces of the conductor pattern film, a via hole is formed in the conductor pattern film, and a filling step of filling the via hole with an interlayer connection material,
A laminating step of laminating a plurality of resin films including the conductor pattern film, and pressing the laminated resin films while heating them with a hot press plate, thereby bonding the resin films to each other to form a multilayer printed circuit board. Heating and pressurizing process,
In each of the laminated resin films, a slit forming step of forming a plurality of slits so as to surround a product region used as a product is performed, and the product region is connected via a connecting portion between the plurality of slits. A printed circuit board manufacturing method characterized by being held by an outer frame portion. The method according to claim 1, wherein, in the slit forming step, the plurality of slits are formed such that positions of the connecting portions are different in the laminated resin films. The method according to claim 1, wherein an outer edge frame made of the conductor pattern is formed at an outer edge of the laminated resin film. The method for manufacturing a printed circuit board according to claim 1, wherein the via hole and the slit are formed by laser processing.

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