JP5077801B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

  The present invention relates to a multilayer printed wiring board in which a plurality of printed wiring boards are laminated, and a method for manufacturing the same.

  The multilayer printed wiring board is known as a technology that enables high-density mounting of components and can connect the components at the shortest distance (meaning that they are electrically connected. Hereinafter, simply referred to as “connection”). .

  For example, in Japanese Patent Application Laid-Open No. 2004-95963 (Patent Document 1), an insulating base material (single-sided substrate) provided with a conductive layer (conductor circuit) forming a wiring pattern on one side reaches the conductive layer, and the other surface. A plurality of wiring board bases formed with conductive resin portions having bumps projecting to the bumps are in contact with conductive layers of other wiring board bases, and an adhesive is sandwiched between the wiring board bases. A method for producing a multilayer printed wiring board for laminating and pressing is described. However, in this method, single-sided substrates are sequentially laminated in one direction and batch-laminated press is performed, so the single-sided substrate located on the outermost side has the surface of the insulating base on the outside, so component mounting on both surfaces But it becomes impossible.

  In order to enable component mounting on both surfaces, a copper foil is placed on the surface of the insulating base located on the outermost side and laminated, and after the lamination press, this copper foil is etched (circuit etching) Thus, a method of forming a circuit is conceivable. In addition, it is possible to mount components on both surfaces by using an insulating base material (double-sided board) with metal foil circuits on both surfaces in the center and laminating the single-sided board as described above on both sides. (Patent Document 2: Japanese Patent Laid-Open No. 2001-15920).

However, the former method requires an etching process after batch stacking, and the latter method also requires an etching process for forming a metal foil circuit on a double-sided substrate or a single-sided substrate, which makes the process very troublesome. In the former method, the etching process is performed after the laminating press in which the dimensional change occurs. Therefore, there is a problem that the circuit is likely to be misaligned during the etching process. In the latter method, the metal foil other than the surface layer is formed. There is a problem that the cost is high because expensive metal such as copper foil is removed.
JP 2004-95963 A JP 2001-15920 A

  An object of the present invention is to provide a multilayer printed wiring board capable of mounting components at high density on both surfaces thereof. Another object of the present invention is to provide a method for producing a multilayer printed wiring board capable of producing a multilayer printed wiring board capable of high-density component mounting on both surfaces thereof at a low cost with a simple process.

  As a result of the study, the present inventor has pasted at least two insulating substrates having a circuit formed of a conductive resin composition on one surface thereof with an adhesive so that the circuit is at least on both outer sides. A multilayer printed wiring board comprising a laminate formed by connecting the circuits on both sides by a conductive portion made of a conductive resin composition formed in an insulating substrate and in an adhesive layer, It has been found that the above problems can be solved.

  Further, the inventor comprises an insulating substrate having a circuit formed of a conductive resin composition on at least one surface thereof, a conductive portion formed of the conductive resin composition in the insulating substrate, and By using a wiring board base material having a bump formed of a conductive resin composition on the conductive portion, and by laminating the conductive portion of the wiring board base material by the bump, the multilayer print It has been found that a wiring board can be manufactured by a simple process. The present invention has been completed based on these findings.

  The present invention comprises an insulating substrate provided with a circuit formed of a conductive resin composition A on at least one surface thereof, and a wiring having a via hole that reaches one circuit and opens on the other surface in the insulating substrate. Two sheets of plate base material and an adhesive layer having through-holes in contact with the openings so that the openings at both ends include the openings of the via holes, and the via holes and the through-holes are electrically conductive. A multilayer printed wiring board comprising a laminate having an inter-circuit conductive portion filled with a conductive resin composition B is provided (claim 1).

  Here, as the insulating substrate, an insulating resin film can be used. For example, a resin film mainly composed of PET or polyimide is exemplified. Among them, the resin film mainly composed of polyimide is a heat-resistant film, can meet the demand for high heat resistance corresponding to the use of lead-free solder, and has low loss in high-frequency transmission compared to resin containing ceramic and glass cloth. In addition, the thickness and strength of the insulating substrate can be reduced, which is preferable (claim 2).

  The insulating substrate constituting the wiring board base is provided with a circuit made of a conductive resin composition on at least one surface thereof. This circuit may be provided on one surface of the insulating substrate, or may be provided on both surfaces. The conductive resin composition forming this circuit is referred to as conductive resin composition A.

  Examples of the conductive resin composition A include those obtained by kneading conductive particles, for example, metal fine particles, metal fillers, carbon fine particles, etc., into a resin that is easily plastically deformed. Specifically, silver paste or silver coat Examples include a copper filler, a copper filler and a carbon mixture paste.

  The circuit can be formed by coating the conductive resin composition A on an insulating substrate by means such as screen printing. Therefore, unlike a conductor layer formed by a metal foil circuit, a process such as etching is not required, and the process can be simplified.

  In the insulating substrate, a via hole (bottomed hole) that reaches one circuit and opens on the other surface is formed. Here, “to reach one circuit” means that one circuit is the bottom of the via hole. When circuits are provided on both surfaces of the insulating substrate, the via hole has one circuit at the bottom, penetrates the insulating substrate and the other circuit, and forms an opening on the other circuit.

  The via hole can be formed by performing drilling using a laser, a drill, a mold, or the like at a position where interlayer connection of the insulating substrate is desired. Unlike the case where via holes are formed on a single-sided or double-sided board with a metal foil circuit, it is possible to process a large number of sheets and eliminate the need for a smear removal process for the copper foil part of the via hole part. Is advantageous.

  The multilayer printed wiring board of the present invention is characterized in that it includes a laminate in which at least part of the multilayer printed wiring board (the center in the thickness direction) is bonded with an adhesive. The adhesive layer has through holes. The two wiring board base materials and the adhesive have a circuit on both outer sides (surfaces) of the obtained laminate, and the openings at both ends of the adhesive through-holes are two wiring board bases. It arrange | positions so that the opening part of the via hole of material may be included, respectively. Here, “the opening of the through hole is arranged so as to include the opening of the via hole” means that both of the openings of the via hole are in the opening of the through hole so that most or all of the openings are in the opening of the through hole. Means contact.

  When the elastic modulus of the adhesive layer is 1 GPa or less, the stress at the time of reflow when a component is mounted on the multilayer printed wiring board is reduced, and this is preferable because of excellent reflow resistance and reliability. On the other hand, if the elastic modulus is less than 0.001 GPa, the amount of deformation (elongation) becomes so large that it may be difficult to handle, so 0.001 GPa or more is preferable (Invention of Claim 3).

  However, in the case of a composite composed of two or more members, when a member having an elastic modulus of 0.001 to 1 GPa is included, even when the overall elastic modulus exceeds 1 GPa, the portion is reflowed. This is preferable in the same manner as in the third aspect (invention of the fourth aspect).

  Examples of the composite adhesive composed of two or more members include a sheet obtained by impregnating a high-rigidity porous material with an adhesive, and a sheet obtained by sandwiching a high-rigidity insulating film layer between two adhesive layers. Etc. are exemplified.

  Examples of the adhesive forming the adhesive sheet include a thermoplastic polyimide resin, a resin mainly composed of thermoplastic polyimide and a part of the thermosetting function, and a thermosetting resin such as an epoxy resin and an imide resin. Among these, a resin mainly composed of thermoplastic polyimide and partly having a thermosetting function, a thermosetting epoxy resin, and a thermosetting imide resin are preferable because sufficient adhesive strength is ensured after heat curing. Moreover, the formation method of a through-hole is not specifically limited, The method of drilling mechanically using a drilling etc. with a laser, a drill, etc. is employable.

  As described above, the openings at both ends of the adhesive through-holes include the openings of the via holes of the two wiring board bases, respectively. A hole is formed in a circuit that reaches both ends of the circuit. In the multilayer printed wiring board of the present invention, the hole is filled with the conductive resin composition, and the circuits on both outer sides of the laminate are connected. (This conductive resin composition is referred to as a conductive resin composition B. Hereinafter, the holes filled with the conductive resin composition B are simply referred to as “conductive portions”).

  Examples of the conductive resin composition B include those obtained by kneading conductive particles, for example, metal fine particles, metal fillers, carbon fine particles, and the like into a resin that is easily plastically deformed, as in the case of the conductive resin composition A. Specifically, silver paste, silver-coated copper filler, copper filler, carbon mixture paste, and the like are exemplified. Examples of the resin that easily undergoes plastic deformation include epoxy resins, polyester resins, polyimide resins, polyamide resins, and liquid crystal polymers.

  The conductive resin composition A and the conductive resin composition B may be conductive resin compositions having different blending compositions, but the process is simplified, and the current value and the resistance value change at the interface between the two. From the viewpoint of the above, it is preferable to use the same one.

  The multilayer printed wiring board of the present invention includes the above laminate, that is, a laminate having a circuit formed of the conductive resin composition A on both surfaces thereof. Other wiring board base materials are bonded and laminated with an adhesive. As another wiring board base material, it has an insulating substrate and a conductor layer provided on at least one surface thereof, and a conductive portion provided in the insulating substrate and in the adhesive, The circuit on the outside and the conductor layer of the other wiring board substrate are connected. The conductive portion is obtained, for example, by filling a conductive resin composition into a via hole provided in the insulating substrate and a through hole provided in the adhesive and the opening portion being in contact with the opening portion of the via hole. be able to.

  The conductor layer of the other wiring board substrate is a circuit made of a metal foil or a conductive resin composition. As described above, the multilayer printed circuit board is formed by connecting the multilayer circuits through the conductive portions. In addition, one or more similar wiring board substrates can be laminated on the outer side of the other laminated wiring board substrates, and a multilayer printed wiring board composed of more circuit layers is formed. Is done.

  As described above, examples of the conductor layer of the other wiring board substrate include a metal foil circuit and a circuit made of a conductive resin composition. The formation of the metal foil circuit requires a complicated process such as etching, whereas the circuit made of the conductive resin composition is excellent in that it can be formed by a relatively simple process such as screen printing. For circuits other than the outermost layer of the multilayer printed wiring board, a circuit made of a conductive resin composition is preferably used.

  However, since a circuit made of a conductive resin composition is inferior to a metal foil circuit in terms of high-temperature heat resistance, problems such as poor conductivity may occur in reflow when mounting components on the outermost layer circuit. This is more likely to occur. Therefore, a metal foil circuit is preferable for the outermost layer circuit. Claim 5 corresponds to this preferable mode.

  The metal foil circuit can be formed, for example, by etching a metal foil such as a copper foil attached on an insulating substrate. For example, after forming a resist layer circuit pattern on a metal foil, immersing the metal foil in an etchant that corrodes the metal foil, removing portions other than the circuit pattern, and then removing the resist layer. Is done. Examples of the etchant in this case include a ferric chloride-based etchant mainly composed of ferric chloride, a cupric chloride-based etchant, and an alkali etchant. Moreover, as an insulating board | substrate which affixed metal foil, the polyimide resin base material (CCL) with copper foil is illustrated.

  As a material for forming the metal foil circuit, a material mainly composed of copper is preferably exemplified from the viewpoints of conductivity, durability, availability, and the like (Claim 6). Examples of the material mainly composed of copper include copper or an alloy mainly composed of copper. As a material for the metal foil circuit, silver, aluminum, nickel or the like is used in addition to copper.

  The present invention further provides a method for producing the multilayer printed wiring board.

  That is, the present invention comprises an insulating substrate provided with a circuit formed of the conductive resin composition A on at least one surface of the insulating substrate according to claim 7, wherein one circuit reaches the other surface in the insulating substrate. Insulation provided with a circuit board substrate a having a conductive resin portion formed by filling a conductive resin composition B into a via hole opened in step 1 and a circuit formed of the conductive resin composition A on at least one surface thereof The insulating substrate has a conductive resin portion formed by filling the conductive resin composition B in a via hole that reaches one circuit and opens on the other surface, and further includes a conductive resin portion on the conductive resin portion. A plurality of wiring board base materials including at least two wiring board base materials b having bumps formed of the conductive resin composition B, a conductive resin portion of the wiring board base material a, and a bump of the wiring board base material b And contact Laminated by sandwiching an adhesive between the substrates, to provide a method of manufacturing a multilayer printed wiring board, which comprises laminating press collectively these.

  The insulating substrate, circuit, and via hole of the wiring board substrate a and the wiring board substrate b are the same as the insulating substrate, circuit, and via hole described in the above description of the multilayer printed wiring board of the present invention.

  The wiring board base material a has a conductive resin portion formed by filling a via hole with a conductive resin composition. Since the conductive resin portion forms the inter-circuit conductive portion, the conductive resin composition forming the conductive resin portion is the conductive resin composition B. Although the filling method of the conductive resin composition B is not specifically limited, For example, the method of filling by screen printing is mentioned.

  The wiring board base b is formed by further forming a conductive bump on the conductive resin portion of the wiring board base a. The bump of the conductive material is a protrusion of the conductive material. Since the conductive bump also forms the inter-circuit conductive portion, the conductive resin composition forming the bump is also the conductive resin composition B.

  The method for forming the conductive bump is not particularly limited. For example, a release layer made of polyethylene terephthalate (PET) or the like is formed on an insulating substrate, and a via hole penetrating the insulating substrate and the release layer is formed. Then, after filling the via hole with the conductive resin composition B, a method of peeling the release layer and forming the protrusion is exemplified. Another method for forming a conductive bump is a method in which a conductive resin composition B is filled in a via hole, and then the conductive resin composition B is applied thereon by screen printing.

  In the method for manufacturing a multilayer printed wiring board according to the seventh aspect, a plurality of wiring board base materials including at least two of the wiring board base material a and the wiring board base material b are laminated. Lamination is performed such that the conductive resin portion of the wiring board substrate a and the bumps of the wiring board substrate b are in contact with each other.

  Lamination is performed by sandwiching an adhesive between the wiring board base material a and the wiring board base material b. When another wiring board base material is further laminated, an adhesive is sandwiched between the other wiring board base materials, and these are collectively laminated. By this lamination press, the bump is deformed, and the conductive portion is formed between the wiring board base materials. Since this conductive portion covers the surface portion of the conductive resin portion of the wiring board base material a, the wiring board base material a And the circuit of the wiring board base b are connected by a conductive part formed by deforming the conductive resin part and the bump of the wiring board base.

  The present invention further includes an insulating substrate provided with a circuit formed of the conductive resin composition A on at least one surface thereof in claim 8, wherein one circuit is formed in the insulating substrate. A wiring board substrate b having a conductive resin part formed by filling a conductive resin composition B in a via hole opened on the surface, and further having a bump formed of the conductive resin composition B on the conductive resin part A plurality of wiring board base materials including at least two of the wiring board base materials b so that the bumps of the two wiring board base materials b are in contact with each other and sandwiching an adhesive between the wiring board base materials, A method for manufacturing a multilayer printed wiring board is provided.

  The aspect of claim 8 is characterized in that two wiring board bases b having bumps are laminated so that the bumps are in contact with each other, and is the same as the aspect of claim 7 in other points. . Both bumps are deformed and integrated by the laminating press, and a conductive portion is formed between the wiring board substrates. Since each bump is connected to the conductive resin portion of each wiring board substrate, this integration connects the circuits of the two wiring board substrates b.

  In any embodiment, the lamination press can be performed by heating and pressurizing with a cure press or the like.

  In the method for producing a multilayer printed wiring board according to the present invention, the wiring board base material a and / or the wiring board base material b is usually laminated by adding a wiring board base material to the outside. This wiring board substrate is composed of an insulating substrate provided with a conductor layer on one surface thereof, and the conductive resin composition B is formed in the insulating substrate in a via hole that reaches one conductor layer and opens on the other surface. And a bump formed of a conductive resin composition B on the conductive resin portion, and the bump and another wiring board substrate (wiring board substrate a or wiring). The circuit board is laminated so that the circuit of the board base material b is in contact with it (claim 9). By this method, a multilayer printed wiring board having three or more layers can be obtained. Here, the conductor layer is exemplified by a metal foil circuit or a circuit made of a conductive resin composition.

  Furthermore, the present invention is the method for producing a multilayer printed wiring board having three or more layers according to claim 10, wherein a wiring board substrate comprising an insulating substrate provided with a metal foil circuit on one surface thereof, Provided is a method for manufacturing a multilayer printed wiring board, wherein the metal foil circuit is arranged and laminated so as to be an outermost layer. By using a metal foil circuit as the outermost layer, a multilayer printed wiring board having three or more layers having high reflow resistance and reliability that can sufficiently withstand reflow during component mounting can be obtained.

  In the method for producing a multilayer printed wiring board of the present invention, the wiring board substrate a and / or the wiring board substrate b and the other wiring board substrate are stacked with an adhesive sandwiched between them, Press the layers together. That is, since the multilayer printed wiring board of the present invention can be produced by a single laminating press, high productivity can be obtained.

  Examples of a method for sandwiching the adhesive include a method of using an adhesive sheet and sandwiching the sheet. For example, a method of using an adhesive sheet having a through hole at a position corresponding to the bump, and stacking the wiring board substrate b and the adhesive sheet so that the bump is inserted into the through hole can be mentioned. Claim 11 corresponds to an embodiment using this adhesive sheet.

  The diameter of the through hole is preferably about 0.5 to 5 times the diameter (maximum diameter) of the bump. If it is 0.5 times or more, alignment of the through hole and the bump becomes easy. In this case, there is a gap between the adhesive sheet and the bump before the lamination press, but if the diameter of the through hole is about 5 times or less than the diameter of the bump, the adhesive sheet is expanded by the lamination press. The bumps are also plastically deformed so that the conductive material of the bumps and the adhesive are in contact with each other, and this gap is easily eliminated.

  In addition, when stacking the adhesive sheet and the wiring board base material, it is preferable to perform temporary bonding that is simple bonding in order to prevent deviation during lamination or lamination pressing. Compared to the combination, the conditions are much milder.

  As the melt viscosity of the adhesive sheet, the adhesive sheet preferably has a minimum melt viscosity at 100 to 250 ° C. in the range of 500 to 50000 Pa · s. If the melt viscosity is higher than the upper limit of this range, the gap between the bump and the adhesive sheet may be difficult to be eliminated during lamination. On the other hand, if it is lower than the lower limit of this range, the adhesive tends to flow into the interface between the bumps or between the conductive resin part and the bumps, which may cause poor connection. Claim 12 corresponds to this preferred embodiment.

  However, in the case where the adhesive sheet is a composite composed of two or more members, if a member having a melt viscosity in the range of 500 to 50000 Pa · s at 100 to 250 ° C. is included, Since the gap between the bump and the adhesive sheet can be eliminated, it is preferable as in the case of the eleventh aspect. Claim 13 corresponds to this preferred mode.

  Examples of the composite adhesive sheet composed of two or more members include a sheet obtained by impregnating a porous material with an adhesive, and a sheet obtained by sandwiching an insulating film layer between two adhesive layers.

  The multilayer printed wiring board of the present invention is capable of high-density component mounting on both surfaces thereof, and has little misalignment between the wiring boards. Therefore, the multilayer printed wiring board is highly reliable and suitable for manufacturing various electric appliances. Used for. Further, the circuit constituting the multilayer printed wiring board can be formed by a simple process such as printing of the conductive resin composition, and does not require a complicated process such as etching, so that it can be easily manufactured. Is. Moreover, according to the method for producing a multilayer printed wiring board of the present invention, this excellent multilayer printed wiring board can be produced by a simple process.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. It should be noted that the scope of the present invention is not limited to this form or the examples described later, and can be changed to other forms as long as the gist of the present invention is not impaired.

  The laminate included in the multilayer printed wiring board of the present invention is composed of two wiring board substrates, and each of the two wiring board substrates has a conductive resin composition A on at least one surface thereof. The circuit formed by is provided. That is, as a combination of two wiring board base materials, a combination of two single-sided base materials provided with a circuit formed of the conductive resin composition A on one surface, and the conductive resin composition A on one surface. A combination of a single-sided base material provided with a circuit formed by the above and a double-sided base material provided with a circuit formed of the conductive resin composition A on both surfaces, and a circuit formed of the conductive resin composition A on both surfaces A combination of two sheets of double-sided base material is possible.

  FIG. 1 is a schematic cross-sectional view showing a multilayer printed wiring board according to the present invention when the laminate is a combination of two single-sided substrates. In FIG. 1, a laminate 51 includes a single-sided base material 31 made of a circuit 11 (hereinafter simply referred to as a circuit 11) formed of a polyimide film 21 and a conductive resin composition A, a polyimide film 22, and a conductive resin composition. The polyimide film 21 and the polyimide film 22 are bonded to the single-sided base material 32 composed of the circuit 12 (hereinafter simply referred to as the circuit 12) formed of the object A via the adhesive layer 41 having an elastic modulus of 0.001 to 1 GPa. Glued between.

  In the laminated body 51, a hole extending from the circuit 11 to the circuit 12 and penetrating the polyimide film 21, the polyimide film 22, and the adhesive layer 41 is formed. The hole is filled with the conductive resin composition B, and the conductive body is electrically conductive. Part 61 is formed. As a result, the circuit 11 and the circuit 12 are connected. The hole in which the conductive portion 61 is formed is obtained by connecting the via holes 215 and 225 formed in the polyimide film 21 and the polyimide film 22, respectively, and the through hole 412 formed in the adhesive layer 41. As shown in FIG. 1, the openings at both ends of the through hole 412 are larger than the openings of the via holes 215 and 225, respectively.

  On both outer sides of the laminate 51, a single-sided base material 33 in which a circuit 13 (hereinafter simply referred to as a circuit 13) formed of a conductive resin composition A is formed on a polyimide film 23, and conductive A single-sided base material 34 in which a circuit 14 (hereinafter simply referred to as a circuit 14) formed of the resin composition A is formed on a polyimide film 24 is laminated. Lamination is performed by bonding polyimide films 23 and 24 with adhesive layers 42 and 43, respectively.

  In the hole where the via hole in the polyimide film 23 and the through hole in the adhesive layer 42 are connected, the conductive resin composition B is filled, and the conductive portion 62 is formed. Similarly, the conductive resin composition B is filled in the hole in which the via hole in the polyimide film 24 and the through hole in the adhesive layer 43 are connected, and the conductive portion 63 is formed. The circuits 13 and 14 are connected to the circuits 11 and 12 on the stacked body 51 by the conductive portions 62 and 63, respectively.

  Similarly, on the circuit 13 and the circuit 14, a single-sided substrate 35 in which a circuit 15 (hereinafter simply referred to as a circuit 15) formed of the conductive resin composition A is formed on a polyimide film 25, and The single-sided base material 36 in which the circuit 16 (hereinafter simply referred to as the circuit 16) formed of the conductive resin composition A is formed on the polyimide film 26 is laminated and bonded by the adhesive layers 44 and 45, respectively. Yes. The circuit 15 and the circuit 16 are formed by the conductive portions 64 and 65 formed by filling the via holes in the polyimide films 25 and 26 and the through holes in the adhesive layers 44 and 45 with the conductive resin composition B. Are connected to the circuit 13 and the circuit 14, respectively, to form a multilayer printed wiring board.

  FIG. 2 is a schematic cross-sectional view showing one process of manufacturing the multilayer printed wiring board of the present invention. In FIG. 2, 31 'and 32' are the wiring board base material b and the wiring board base material a, respectively. The wiring board substrate b31 'includes the polyimide film 21 and the circuit 11 formed on one surface thereof. Here, the circuit 11 is obtained by screen-printing the conductive resin composition A (the same applies to a circuit made of the following conductive resin composition). In the polyimide film 21, a via hole having the circuit 11 at the bottom and opening at another surface is formed, and the conductive resin filled with the conductive resin composition B by screen printing the conductive resin composition B. A portion 811 is formed, and a bump 812 is formed on the conductive resin portion 811 by screen printing the conductive resin composition B.

  The wiring board substrate a32 'is composed of the polyimide film 22 and the circuit 12 formed on one surface thereof. A via hole is formed in the polyimide film 22 with the circuit 12 at the bottom and opening on the other surface, and the conductive resin portion B is filled with the conductive resin composition B by screen printing the conductive resin composition B. 821 is formed.

  Between the wiring board base material a32 ′ and the wiring board base material b31 ′, an adhesive sheet 411 made of an adhesive having a cured elastic modulus of 0.001 to 1 GPa is disposed, and the conductive resin portion 821 and the bumps 812 are disposed. The wiring board substrate a32 ′, the wiring board substrate b31 ′, and the adhesive sheet 411 are arranged so that the bumps 812 are inserted into the through holes 412 formed in the adhesive sheet 411 so as to face each other.

  An adhesive sheet 421 made of an adhesive having an elastic modulus after curing of 0.001 to 1 GPa is disposed on the outside of the wiring board substrate b31 ′, and further formed on the polyimide film 23 and one surface thereof on the outside. The single-sided base material 33 ′ having the conductive resin portion 831 and the bumps 832 formed by screen-printing the conductive resin composition B is disposed in the via hole in the polyimide film 23. In the wiring board base material b31 ′, the adhesive sheet 421, and the single-sided base material 33 ′, the bumps 832 are inserted into the through holes 422 formed in the adhesive sheet 421 so that the circuit 11 and the bumps 832 face each other. Are arranged as follows.

  Similarly, an adhesive sheet 441 made of an adhesive having a cured elastic modulus of 0.001 to 1 GPa is disposed on the outer side of the single-sided base material 33 ′, and the polyimide film 25 and one surface thereof are further disposed on the outer side. The single-sided base material 35 ′ comprising the circuit 15 formed above and having the conductive resin portion 851 and the bumps 852 formed by screen-printing the conductive resin composition B in the via hole in the polyimide film 25 is formed as a circuit 13. And the bumps 852 are opposed to each other, and the bumps 852 are inserted into the through holes 442 formed in the adhesive sheet 441.

  The same applies to the outside of the wiring board substrate a32 ′, which is composed of the adhesive sheet 431, the polyimide film 24, and the circuit 14 formed on one surface thereof, and the conductive resin composition B is applied to the via hole in the polyimide film 24. A via hole in the polyimide film 26, which is composed of a single-sided base material 34 ′ having a conductive resin portion 841 and bumps 842 formed by screen printing, an adhesive sheet 451, a polyimide film 26 and a circuit 16 formed on one surface thereof. In addition, through-holes formed in the adhesive sheet 431 and the adhesive sheet 451 respectively in the order of the single-sided base material 36 ′ having the conductive resin portion 861 and the bumps 862 formed by screen-printing the conductive resin composition B. Bumps 842 and 862 are respectively inserted into 432 and 452, and the bumps 842 are provided. 862, respectively, are arranged so as to face the circuit 12.

  After arranging the adhesive sheet, the single-sided base material, and the wiring board base material as described above, these are pressure-pressed collectively by a cure press. Each bump is plastically deformed by the pressure press, and each adhesive sheet is also plastically deformed, and the gap between each adhesive sheet and each bump is eliminated, and the multilayer printed wiring board of the present invention shown in FIG. 1 is formed. Is done. An inter-circuit conductive portion and a conductive portion are formed by the conductive resin portions and the bumps.

  The above manufacturing method can be performed in the same manner by using two pieces of the wiring board base material b instead of the wiring board base material b31 'and the wiring board base material a32'. In this case, the two wiring board bases b are arranged with the adhesive sheet sandwiched therebetween so that the respective bumps face each other, but in other respects, the manufacturing method is the same as that shown in FIG. The multilayer printed wiring board of this invention shown by is formed.

  FIG. 3 is a schematic cross-sectional view showing the multilayer printed wiring board of the present invention when the laminate is a combination of a single-sided base material and a double-sided base material. In FIG. 3, the laminate 52 includes a single-sided base material 311 composed of a polyimide film 211 and a circuit 111 (hereinafter simply referred to as a circuit 111) formed of a conductive resin composition A formed on the surface thereof, and A double-sided base material 321 composed of a circuit 121 (hereinafter simply referred to as a circuit 121) and 122 formed of a polyimide resin 221 and a conductive resin composition A formed on both surfaces thereof has an elastic modulus of 0.001 to 0.001. The adhesive layer 46 of 1 GPa is formed by bonding between the polyimide film 211 and the circuit 122 (hereinafter simply referred to as the circuit 122) formed of the conductive resin composition A. Except for the above points, it is the same as the example of FIG. 1 (however, the number of laminated single-sided substrates is small) and can be manufactured by the same method.

  FIG. 4 is a schematic cross-sectional view showing the multilayer printed wiring board of the present invention when the laminate is a combination of two double-sided base materials. In FIG. 4, a laminate 53 is a double-sided structure composed of a polyimide film 212 and circuits 112 and 113 (hereinafter simply referred to as circuits 112 and 113) formed by the conductive resin composition A formed on both surfaces thereof. A double-sided base material 322 composed of a base material 312, a polyimide film 222, and circuits 123 and 124 (hereinafter simply referred to as circuits 123 and 124) formed by the conductive resin composition A formed on both surfaces thereof, respectively. The adhesive layer 47 having an elastic modulus of 0.001 GPa or more and 1 GPa or less is formed by bonding the circuits 113 and 124 together. Except for the above points, it is the same as the example of FIG. 1 and can be manufactured by the same method.

  In addition, the multilayer printed wiring board (invention of Claim 5) characterized by having a metal foil circuit in the outermost layer is the circuit of the outermost layer of the laminate shown in FIGS. 15 and 16) in FIG. 2 can be formed by a method similar to the above except that the metal foil circuit is used.

[Preparation of conductive paste]
A solution using butyl carbitol acetate as a solvent was prepared on an epoxy resin consisting of 70 parts by weight of an bisphenol A type epoxy resin (epoxy equivalents 7000-8500) and 30 parts by weight of a bisphenol F type epoxy resin (epoxy equivalents 160-170). A silver paste was prepared by adding an imidazole-based latent curing agent to obtain a conductive paste (conductive resin compositions A and B). Upon application, viscosity adjustment was performed using a solvent as necessary.

[Production of single-sided paste wiring board substrate]
A substrate (PI: 25 μm, layer thickness: 18 μm) is prepared by applying a conductive paste by screen printing on one side of a polyimide film (PI) with a total of eight through-holes (opening diameter 150 μm) formed by a drill. did. During screen printing, a slightly adhesive polyester film or the like was pasted on the back side of the printing surface to prevent paste leakage from the through hole.

  A conductive paste was filled into each via hole by screen printing at a portion where each through hole on the back side of the printing surface was opened, and temporary curing was performed. Furthermore, the conductive paste was screen-printed to form a total of eight bumps (convex portions) having a diameter of 250 μm and a height of 60 μm, and temporary curing was performed. In this way, a single-sided paste wiring board substrate (with bumps) corresponding to 31 ', 33', and 34 'in FIG.

  Further, a single-sided paste wiring board substrate (no bump) corresponding to 32 'in FIG. 2 was produced in the same manner as the above method except that no bump was formed.

[Production of single-sided copper foil wiring board substrate]
A circuit was formed on one side of a copper-clad laminate of polyimide 25 microns and copper foil 18 μm, and eight 150 micron diameter via holes were formed by laser from the opposite side. A conductive paste was filled in the via hole portion by screen printing, and temporary curing was performed. Furthermore, the conductive paste was screen-printed to form a total of 8 bumps (convex portions) having a diameter of 250 μm and a height of 60 μm, and pre-cured to prepare a single-sided wiring board substrate.

[Preparation of insulating sheet for interlayer adhesion]
A through hole having a diameter of 350 μm was formed at a predetermined position of an adhesive sheet made of 25 μm-thick epoxy resin (TLF-Y30: manufactured by Yodogawa Paper Mill, minimum melt viscosity of 4700 Pa · s at 100 to 250 ° C.) using a drill. Formed.

[Lamination press]
Two layers of the single-sided copper foil wiring board substrate obtained as described above are arranged on the outermost side, and three layers of the single-sided paste wiring board substrate (with bumps) obtained as described above are arranged on the inner side, and One layer of a single-sided paste wiring board substrate (no bumps) is arranged in the same manner as in 31 ', 32', 33 'and 34' in FIG. 5 layers of insulating sheet for sheeting are superposed so as to insert a bump into the through hole of the insulating sheet for interlayer bonding, and then a bonding process is performed by a vacuum press. After that, 40 interlayer connection portions are connected to the daisy chain. A circuit was formed so that a multilayer printed wiring board was produced.

  Instead of the single-sided paste wiring board substrate (without bumps) used in Example 1, a single-sided paste wiring board substrate (with bumps) was used. Further, only the sheet at the center of the five-layer interlayer insulating insulating sheet (position corresponding to the sheet 411 in FIG. 2) is an adhesive sheet made of an epoxy resin having a thickness of 35 μm (TLF-Y30: manufactured by Yodogawa Paper). What formed the through-hole of diameter 300 micrometers using the drill in the predetermined position was used. In other respects, a multilayer printed wiring board was produced in the same manner as in Example 1.

  Instead of the interlayer adhesive insulating sheet used in Example 1, a 25 μm thick epoxy resin (TLF-Y30F: manufactured by Yodogawa Paper, minimum melt viscosity at 100 to 250 ° C. is 21000 Pa · s) was used. A multilayer printed wiring board was produced in the same manner as in Example 1.

  Instead of the interlayer adhesive insulating sheet used in Example 1, a 25 μm thick epoxy resin (TLF-Y20: manufactured by Yodogawa Paper Mill, minimum melt viscosity at 100 to 250 ° C. being 700 Pa · s) was used.

  Instead of the insulating sheet for interlayer adhesion used in Example 1, an aramid nonwoven fabric impregnated with resin (EA541: Shin-Kobe Electric, minimum melt viscosity of resin at 100 to 250 ° C. is 63 Pa · s) was used.

[Evaluation test]
In any of Example 1, Example 2, Example 3, and Example 4, conduction was obtained, and the resistance change rate was 10% or less even when the lead-free reflow test was performed three times. On the other hand, in Example 5, the resistance change rate was 15%.

It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention. It is a schematic cross section which shows one process of manufacture of the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention.

Explanation of symbols

11, 12, 13, 14, 15, 16, 111, 112, 113, 121, 122, 123, 124 Circuits 21, 22, 23, 24, 25, 26, 211, 221 formed from a conductive resin composition 212, 222 Polyimide film 215, 225 Via hole 31 'Wiring board base b
32 'Wiring board substrate a
31, 32, 33, 33 ', 34, 34', 35, 35 ', 36, 36', 311 Single-sided base material 312, 321, 322 Double-sided base material 41, 42, 43, 44, 45, 46, 47 Adhesion Agent layer 412, 422, 432, 442, 452 Through hole 51, 52, 53 Laminate 61, 62, 63, 64, 65 Conductive part 811, 821, 831, 841, 851, 861 Conductive resin part 812, 832, 842 , 852, 862 Bump 411, 421, 431, 441, 451 Adhesive sheet

Claims (7)

At least the insulating consists substrate provided with a circuit formed by the conductive resin composition on the 1 on the surface, the via hole opening at the other surface leads to the circuit during this insulating substrate, a conductive resin to form a circuit Insulating substrate provided with a circuit board substrate a having a conductive resin portion filled with a conductive resin composition that is the same as or different from the composition, and a circuit formed of the conductive resin composition on at least one surface thereof A conductive resin part formed by filling the insulating substrate with a conductive resin composition that is the same as or different from the conductive resin composition forming the circuit in the via hole that reaches the circuit and opens on the other surface. Furthermore, on the conductive resin portion, a wiring board substrate b having bumps formed of the same or different conductive resin composition as the conductive resin composition forming the circuit,
At least including a plurality of wiring board substrate two, and the conductive resin portion of the wiring board substrate a, as bumps of the wiring board substrate b is in contact, and between the wiring board substrate, corresponding to the bumps A multilayer printed wiring comprising sandwiching an adhesive sheet having a through-hole at a position where the bump is inserted and laminating the bump so that the bump is inserted into the through-hole, and laminating and pressing them together A manufacturing method of a board. At least the insulating consists substrate provided with a circuit formed of a conductive resin composition part 1 on the surface, the via hole opening at the other surface leads to the circuit during this insulating substrate, a conductive resin to form a circuit A conductive resin portion formed by filling the same or different conductive resin composition as the composition , and further, on the conductive resin portion , the same or different conductive resin composition as the conductive resin composition forming the circuit A plurality of wiring board substrates including at least two of the wiring board substrates b having the formed bumps,
An adhesive sheet having a through hole at a position corresponding to the bump is sandwiched between the wiring board bases so that the bumps of the two wiring board bases b are in contact with each other, and the bumps pass through the through-holes A method for producing a multilayer printed wiring board , comprising: arranging and laminating so as to be inserted into holes, and laminating and laminating them together. In addition to the wiring board substrate a and / or the wiring board substrate b, the plurality of wiring board substrates are further provided with a circuit formed of a metal foil circuit or a conductive resin composition on at least one surface thereof. A conductive resin portion formed by filling a conductive resin composition into a via hole that reaches one circuit and opens on the other surface, and further on the conductive resin portion. includes a wiring board substrate having bumps formed by conductive resin composition, to claim 1 or claim 2, characterized in that laminated so that the circuit of the bump and another wiring board base material are in contact The manufacturing method of the multilayer printed wiring board as described. 4. The method for producing a multilayer printed wiring board according to claim 3 , wherein the outermost layer is disposed and laminated so that the outermost layer is a wiring board substrate having a metal staying circuit. The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 4, wherein the insulating substrate is a resin film mainly composed of polyimide. 6. The multilayer printed wiring board according to claim 1 , wherein a minimum melt viscosity at 100 to 250 ° C. of the adhesive sheet is in a range of 500 to 50000 Pa · s. Production method. The said adhesive agent sheet is a composite_body | complex containing the member which has a melt viscosity in the range of 500-50000 Pa.s in the minimum melt viscosity in 100-250 degreeC, The any one of Claim 1 thru | or 5 characterized by the above-mentioned. 2. A method for producing a multilayer printed wiring board according to item 1 .

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