JP2004273575A - Multilayer printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve connection reliability of conductor patterns which are laminated via a thermoplastic resin film and conductive paste with which vias are filled. <P>SOLUTION: In this multilayer printed wiring board, a lamination base material selected out of an interlayer connection base material 1 wherein vias 5 which penetrate the thermoplastic resin film 4 in the thickness direction are filled with a conductive paste 6 in which binder composed of thermoplastic resin and conductive material are mixed, a double sided wiring base material 2 wherein a conducting pattern 8 is formed on both surfaces of the interlayer connection substrate 1, and a one side wiring base material 3 wherein the conducting pattern 8 is formed on one side of the interlayer connection base material 1. The lamination base material are subjected to thermal fusion or bonded with adhesives in the state that the plurality of the conducting patterns 8 are laminated via the thermoplastic resin film 4 and laminated in an unified body. At the same time, the parts between the respective layers of the conducting patterns 8 which are laminated via the thermoplastic resin film 4 are subjected to interlayer connection with the conductive paste 6 with which the vias 5 are filled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multilayer printed wiring board in which an interlayer connection is made with a conductive paste and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In electronic devices, in order to meet the demand for miniaturization and weight reduction, electronic components such as semiconductor elements and chip components constituting the electronic circuit are miniaturized and mounted at high density on a printed wiring board. In printed wiring boards, as the number of wirings increases due to the higher integration of semiconductor elements to be mounted, conductor patterns are miniaturized, the spacing (pitch) is reduced, and the wiring density is increased by increasing the number of layers. A multi-layer printed wiring board which has been increased in size has been used.
[0003]
This multilayer printed wiring board is, for example, an interlayer connecting base material (prepreg) having an insulating layer made of glass epoxy resin in which glass fiber is impregnated with an epoxy resin, and is thermally fused to one or both surfaces of the interlayer connecting base material. It has a structure in which a plurality of single-sided or double-sided wiring substrates (metal-clad laminates) on which a predetermined conductor pattern is formed by etching a metal foil are stacked and integrated by heat fusion in a state of being stacked. In addition, this multilayer printed wiring board forms a through hole called a through hole in the thickness direction by drilling a hole in order to electrically connect between each layer of the conductor pattern laminated via the insulator layer. In addition, it has a so-called plated through hole structure in which interlayer connection is performed by plating formed in the through hole.
[0004]
[Patent Document 1]
Japanese Patent No. 2601128
[Patent Document 2]
JP 2000-200976 A
[Patent Document 3]
Japanese Patent No. 3251711
[0005]
[Problems to be solved by the invention]
By the way, in the above-mentioned multilayer printed wiring board, the diameter of the through hole has been reduced with the increase in the wiring density and the number of layers, and it has become extremely difficult to form a hole with a drill. For this reason, in a multilayer printed wiring board, instead of the conventional plated through hole structure, a hole called a via (hole) penetrating the insulator layer in the thickness direction is finely formed by laser processing or the like, and the hole is formed in the hole. A so-called IVH (Interstitial Via Hole) structure has been adopted in which each layer of the conductor pattern is connected between layers by the filled conductive paste. When a multilayer printed wiring board having such an IVH structure is manufactured, for example, a conductive paste is applied to a via penetrating an insulator layer in a thickness direction on a double-sided wiring board (metal-clad laminate) serving as a base. A so-called build-up method in which the filled single-sided wiring base material (metal foil with resin) is stacked one by one is used.
[0006]
For example, as a multilayer printed wiring board in which interlayer connection using a conductive paste is performed by using such a build-up method, all layers of a conductor pattern laminated via an insulating layer are connected by an interlayer using a conductive paste. There is a multilayer printed wiring board having a so-called ALIVH (Any Layer Inner Via Hole) structure in which build-up is performed while the build-up is being performed (for example, see Patent Document 1).
[0007]
In the multilayer printed wiring board having the ALIVH structure, for example, a via penetrating in the thickness direction is formed by laser processing on a porous base material made of a composite material of an aramid nonwoven fabric and a thermosetting resin, and a conductive paste is formed in the via. After filling, a metal foil serving as a conductor pattern is overlaid and heated and pressurized, whereby an interlayer connection of the conductor pattern is made by a conductive paste. Also, in this multilayer printed wiring board, a part of the binder component contained in the thermosetting conductive paste penetrates into the pores of the porous base material, thereby reducing the density of the conductive material in the conductive paste. Can be enhanced. At the same time, the diluent solvent and low molecular weight components of the resin contained in the conductive paste before curing are also absorbed by the porous substrate. Thus, it is possible to prevent voids (cavities due to bubbles) from being generated in the conductive paste cured after heating and pressurization, and to secure connection reliability between the conductive paste and the conductive pattern.
[0008]
However, in the multilayer printed wiring board having the ALIVH structure, when the spacing between adjacent vias is reduced due to the narrower wiring pitch, the above-described moisture absorption of the porous base material lowers the electrical insulation between the adjacent vias. There is a fear. On the other hand, in order to improve the electrical insulation between adjacent vias, it is conceivable to use a resin film having no hygroscopic property instead of the above-described porous substrate. However, in this case, when heating and pressing are performed before the conductive paste filled in the via is cured, the diluting solvent and the low molecular weight component of the resin contained in the conductive paste are volatilized without being absorbed by the resin film. . For this reason, the above-mentioned voids may be generated in the conductive paste cured after heating and pressurization, and the connection reliability between the conductive paste and the conductive pattern may be reduced.
[0009]
In addition, the diluting solvent and the low molecular weight component of the resin in the conductive paste are indispensable for adjusting the viscosity to an appropriate level. Usually, after printing or preparation, it is general to volatilize by applying heat.
[0010]
Therefore, in order to solve such a problem, it is conceivable to volatilize and remove a diluting solvent and a low molecular weight component of the resin contained in the conductive paste before heating and pressing. However, in this case, since the conductive paste filled in the via hardens before the heating and pressing, it becomes difficult to obtain a sufficient adhesive force between the conductive paste and the conductive pattern.
[0011]
On the other hand, there has been proposed a multilayer printed wiring board in which fine vials penetrating a thermoplastic resin film are filled with fine metal powder and interlayer connection is made between layers of a conductor pattern by metal diffusion (for example, see Patent Document 2). ). However, in this case, it is necessary to sinter the metal powders, and the connection temperature becomes high. Therefore, only a thermoplastic resin film having high heat resistance can be used, and the range of material selection becomes narrow.
[0012]
In addition, using the above-described build-up method, as a multilayer printed wiring board in which interlayer connection using a conductive paste is made, a bump made of a conductive paste is passed through an insulator layer to perform interlayer connection with a conductive pattern. Building up, so-called B ² There is a multilayer printed circuit board having an it (Buried Bump Interconnection Technology) structure (for example, see Patent Document 2).
[0013]
This B ² In the case of a multilayer printed wiring board having an it structure, for example, a conical bump made of a conductive paste is formed on a supporting base sheet made of a metal foil, a thermoplastic resin film is laminated, and then a primary press is performed. Then, the tip of the bump penetrates the thermoplastic resin film, and a metal foil is laminated thereon and subjected to secondary pressure, whereby the metal foil serving as the conductor pattern is interlayer-connected by the bump. .
[0014]
However, this B ² In a multilayer printed wiring board having an it structure, interlayer connection is performed by mechanical contact between a bump and a conductor pattern. Therefore, it is difficult to secure connection reliability between the bump and the conductor pattern due to miniaturization. .
[0015]
Therefore, the present invention has been proposed in view of such a conventional situation, and has a connection reliability when connecting between layers of a conductor pattern laminated via a thermoplastic resin film with a conductive paste. It is an object of the present invention to provide a multilayer printed wiring board having greatly improved performance.
[0016]
Another object of the present invention is to provide a method for manufacturing a multilayer printed wiring board in which the manufacturing process of such a multilayer printed wiring board is simplified and productivity is greatly improved.
[0017]
[Means for Solving the Problems]
In order to achieve this object, a multilayer printed wiring board according to the present invention has a conductive material in which a binder made of a thermoplastic resin and a conductive material are mixed in a hole penetrating an insulating film made of a thermoplastic resin in a thickness direction. An interlayer connection base material filled with a paste, a single-sided wiring base material having a conductive pattern electrically connected to the conductive paste on one side of the interlayer connection base material, and a conductive paste on both surfaces of the interlayer connection base material And a double-sided wiring substrate having a conductor pattern electrically connected thereto and heat-melted in a state in which a plurality of laminated substrates are stacked so that the conductor pattern is laminated via an insulating film. The conductor pattern is laminated or integrated by being adhered with an adhesive, and the conductive paste filled between the layers of the conductor pattern laminated via the insulating film is filled with a hole. It is characterized in that formed by interlayer connection.
[0018]
As described above, in the printed wiring board according to the present invention, since the thermoplastic resin is used for the binder of the conductive paste, the thermoplastic resin is reversibly softened by the heat applied during lamination and integration. By utilizing the method, it is possible to obtain high connection reliability between the conductive paste filled in the hole penetrating the insulator film and the conductor pattern formed on one or both surfaces of the insulator film.
[0019]
Further, in the method of manufacturing a printed wiring board according to the present invention, a hole portion penetrating in a thickness direction is formed in an insulating film made of a thermoplastic resin, and a binder made of a thermoplastic resin and a conductive material are mixed in the hole portion. And a single-sided wiring substrate produced by forming a conductive pattern that is electrically connected to the conductive paste on one side of the interlayer connection substrate. A laminated base material selected from a double-sided wiring base material that is prepared by forming a conductive pattern that is electrically connected to a conductive paste on both surfaces of an interlayer connection base material; Conductors that are heat-sealed in a state of being stacked in multiple layers so as to be laminated via an adhesive, and are bonded and integrated using an adhesive, and laminated via an insulator film It is characterized in that the interlayer connection by turns of each layer between the hole in the filled conductive paste.
[0020]
As described above, in the method for manufacturing a printed wiring board according to the present invention, since the thermoplastic resin is reversibly softened by the heat applied when the layers are integrated, the layers are laminated via the insulating film made of the thermoplastic resin. The layers of the conductive pattern to be formed can be appropriately and easily connected to each other by a conductive paste in which a binder made of a thermoplastic resin and a conductive material are mixed. Furthermore, in the present method, by laminating a plurality of laminated base materials selected from among an interlayer connection base material, a single-sided wiring base material, and a double-sided wiring base material in a stacked state, or by bonding using an adhesive, Such a multilayer printed wiring board with high connection reliability can be manufactured by laminating all together.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a multilayer printed wiring board to which the present invention is applied and a method for manufacturing the same will be described in detail with reference to the drawings.
[0022]
In a multilayer printed wiring board to which the present invention is applied, a layer made of a thermoplastic resin is provided between layers of a conductor pattern laminated via an insulating film made of a thermoplastic resin (hereinafter, referred to as a thermoplastic resin film). The layers are connected by a conductive paste mixed with a conductive substance. That is, in the multilayer printed wiring board, each layer of the conductor pattern is electrically connected by the conductive paste filled in the hole (hereinafter, referred to as a via) penetrating the thermoplastic resin film in the thickness direction. I have.
[0023]
When manufacturing this multilayer printed wiring board, first, as shown in FIG. 1, a laminated base material selected from an interlayer connecting base material 1, a double-sided connecting base material 2, and a single-sided connecting base material 3 is manufactured. I do.
[0024]
The interlayer connection base material 1 is a so-called prepreg, and after (a) forming a via 5 penetrating in the thickness direction on the thermoplastic resin film 4 by laser processing or drilling, etc., finely, c) The via 5 is formed by filling a conductive paste 6 in which a binder made of a thermoplastic resin and a conductive material are mixed by a printing method, a dispensing method, or the like.
[0025]
The double-sided wiring substrate 2 is a so-called metal-clad laminate, and after (d) the metal foil 7 is thermally fused to both surfaces of the interlayer connecting substrate 1 in (c), (e) And a conductor pattern 8 such as a wiring pattern, a land, and a circuit pattern is formed.
[0026]
The single-sided wiring substrate 3 is a so-called resin-attached metal foil, and (f) a metal foil 7 is thermally fused to one surface of the thermoplastic resin film 4 of (a), and (g) the metal foil 7 is thermally fused. Vias 5 penetrating the thermoplastic resin film 4 from the surface opposite to the attached surface to the position facing the metal foil 7 in the thickness direction are finely formed by laser processing, drilling or the like, and (h). After filling the via 5 with a conductive paste 6 by a printing method, a dispensing method or the like, (i) etching the metal foil 7 into a predetermined shape to form a conductor pattern 8 such as a wiring pattern, a land, and a circuit pattern. Produced by Further, the single-sided wiring base material 3 is obtained by (h) heat-sealing a metal foil 7 on one side of the interlayer connection base material 1 (c), and (i) etching the metal foil 7 into a predetermined shape. It can also be manufactured by forming a conductor pattern 8 such as a wiring pattern, a land, and a circuit pattern.
[0027]
The thermoplastic resin film 4 is formed of, for example, a liquid crystal polymer or a film formed of a thermoplastic resin such as a polyetheretherketone resin (PEEK), a polyetherimide resin (PEI), or a polyethersulfone resin (PES). Can be used. In this method, after forming the vias 5 in the thermoplastic resin film 4, desmearing may be performed as necessary to improve the filling property of the conductive paste 6.
[0028]
For the conductive paste 6, a binder may be, for example, a thermoplastic resin such as polyester, polyamide, polycarbonate, or polyvinyl butyral, and a conductive material such as copper, gold, silver, nickel, solder, or the like. A fine powder composed of a filler, an alloy thereof, or a mixture thereof can be used. In addition, a diluting solvent, a low molecular weight component of a resin, or the like may be added to the conductive paste 6 in order to improve printability, whereby the conductive paste can be adjusted to an appropriate viscosity.
[0029]
For the conductor pattern 8, for example, a copper foil or the like can be used as the metal foil 7. Further, in the present method, not only the metal foil 7 thermally fused to the thermoplastic resin film 4 described above, but such a metal foil 7 is formed on one or both surfaces of the thermoplastic resin film 4 by electroless plating. Is also good.
[0030]
Next, a plurality of laminated base materials selected from the interlayer connecting base material 1, the double-sided wiring base material 2, and the single-sided wiring base material 3 are stacked so that the conductor pattern 8 is laminated via the thermoplastic resin film 4. The layers are integrated by heat-sealing in a stacked state or by bonding using an adhesive. At this time, a laminating press step of sandwiching the laminated base material between the hot plates and compressing in the thickness direction while applying heat and pressure is performed. As a result, the respective layers of the conductor pattern 8 stacked via the thermoplastic resin film 4 are interlayer-connected by the conductive paste 6 filled in the via 5. As described above, a multilayer printed wiring board can be manufactured by laminating all at once.
[0031]
In the multilayer printed wiring board manufactured using this method, the number of the conductor patterns 8 to be laminated via the thermoplastic resin film 4 is arbitrary. The arrangement and number of the vias 5 formed in the resin film 4 are also arbitrary.
[0032]
Therefore, for example, a multilayer printed wiring board in which conductive patterns 8 are laminated in four layers via a thermoplastic resin film 4 will be described.
[0033]
As shown in FIGS. 2 and 3, the multilayer printed wiring board having this four-layer structure is formed by laminating the double-sided wiring base material 2, the interlayer connection base material 1, and the double-sided wiring base material 2 in this order. It is a thing. That is, the multilayer printed wiring board is heat-sealed or bonded in a state where the double-sided wiring bases 2 and the interlayer connection bases 1 are alternately laminated so that the double-sided wiring bases 2 sandwich the interlayer connection bases 1. It is manufactured by laminating all together by bonding using.
[0034]
Further, as shown in FIGS. 4 and 5, the multilayer printed wiring board having such a four-layer structure includes the above-described double-sided wiring base 2, single-sided wiring base 3, and single-sided wiring base 3 in order. They may be stacked, laminated and integrated. That is, this multilayer printed wiring board is heat-sealed or bonded using an adhesive in a state where the single-sided wiring substrate 3 is stacked on one surface of the double-sided wiring substrate 2 with the thermoplastic resin film 4 side as a bonding surface. To be collectively laminated.
[0035]
As shown in FIGS. 6 and 7, the multilayer printed wiring board having such a four-layer structure includes the above-described single-sided wiring substrate 3, the double-sided wiring substrate 2, and the single-sided wiring substrate 3 in order. They may be stacked, laminated and integrated. That is, this multilayer printed wiring board is heat-sealed or bonded using an adhesive in a state where the single-sided wiring substrate 3 is stacked on both surfaces of the double-sided wiring substrate 2 with the thermoplastic resin film 4 side as a bonding surface. To be collectively laminated.
[0036]
By the way, in the above-mentioned multilayer printed wiring board, by using a thermoplastic resin as a binder of the conductive paste 6, the conductive paste 6 filled in the via 5 of the thermoplastic resin film 4 and the thermoplastic resin film 4 High connection reliability with the conductor pattern 8 formed on one or both sides is ensured.
[0037]
Specifically, the thermoplastic resin is characterized in that the change between softening and hardening is reversible and there is no deterioration due to heating. For this reason, in the above-described lamination pressing step, the thermoplastic resin film 4 and the conductive paste 6 are reversibly softened by heat applied when the lamination base materials are laminated and integrated. Thereby, a sufficient adhesive force between the conductive paste 6 filled in the vias 5 of the thermoplastic resin film 4 and the conductive patterns 8 formed on one or both surfaces of the thermoplastic resin film 4 can be obtained.
[0038]
Therefore, in this multilayer printed wiring board, when the respective layers of the conductor pattern 8 laminated via the thermoplastic resin film 4 are interlayer-connected by the conductive paste 6, the binder of the conductive paste 6 is coated with the thermoplastic resin. By using it, it is possible to easily and obtain high connection reliability.
[0039]
Thermoplastic resins generally have higher flexibility than hard and brittle resins such as thermosetting resins. Therefore, this multilayer printed wiring board has flexibility when mechanical stress or thermal stress is applied, and by using a thermoplastic resin for the binder of the conductive paste 6, the conductive paste 6 and the conductive pattern 8 can be improved in connection reliability.
[0040]
Further, in this multilayer printed wiring board, in order to prevent voids from being generated in the conductive paste cured after heating and pressing, the diluting solvent and the low molecular weight component of the resin contained in the conductive paste 6 before heating and pressing are removed. Even if it is volatilized, the conductive paste 6 is reversibly softened by applying heat again and fused with the conductive pattern 8.
[0041]
In this manner, in this method, a plurality of laminated base materials selected from the previously prepared interlayer connection base material 1, double-sided wiring base material 2, and single-sided wiring base material 3 are heat-sealed or stacked in a state of being stacked. It is possible to laminate and manufacture such a multilayer printed wiring board having high connection reliability by bonding using.
[0042]
Therefore, this method can simplify the manufacturing process of the multilayer printed wiring board and improve the yield compared to the method of forming one layer at a time as in the conventional build-up method. It is possible to greatly improve productivity.
[0043]
In addition, in this method, even if the above-described laminated base material is prepared and stored in advance, it is not necessary to worry about temporal curing (shelf life) such as a thermosetting resin. There is also an advantage that it becomes easier.
[0044]
Here, the conductive paste 6 preferably has a lower glass transition point Tg than the thermoplastic resin film 4.
[0045]
In this case, in the above-described laminating press step, when the temperature is equal to or higher than the glass transition point Tg of the thermoplastic resin film 4 generally required to fuse the laminated base material, the conductive paste 6 also softens, As well as being fused with the conductor pattern 8, the conductive pastes 6 filled in the vias 5 are fused and integrated. It is needless to say that in the above-described laminating press step, it is preferable that not only the pressure but also the heating temperature be higher than the glass transition point Tg of the conductive paste 6.
[0046]
Thereby, in the multilayer printed wiring board, it is possible to greatly improve the connection reliability when connecting between the layers of the conductor pattern 8 laminated via the thermoplastic resin film 4 by the conductive paste. . Further, compared to the case where the via is filled with fine metal powder and the interlayer connection between the layers of the conductor pattern is performed by metal diffusion, the interlayer connection can be performed at a lower temperature. It is possible to spread.
[0047]
Further, the conductive paste 6 preferably has a lower elastic modulus at the temperature at the time of fusion than the thermoplastic resin film 4.
[0048]
In this case, in the laminating press step shown in FIG. 8, when a plurality of laminated base materials are compressed in the thickness direction in a state of being stacked, the thermoplastic resin film 4 is plastically deformed in a direction to reduce the diameter of the via 5. The thermoplastic conductive paste filled in the via 5 is pressed, and pressure is applied in the vertical direction in contact with the conductive pattern 8. Therefore, as the elastic modulus of the thermoplastic resin film 4 is higher than that of the conductive paste 6, the fusion between the conductive paste 6 filled in the via 5 and the conductive pattern 8 can be promoted.
[0049]
Further, the conductor pattern 8 is compressed in a state where a plurality of laminated base materials are stacked, so that the conductive pattern 8 is partially embedded in the conductive paste 6 filled in the via 5 as shown in FIG. ing. (A) shows a state in which the conductor pattern 8 straddles the via 5, and (b) shows a state in which the tip of the conductor pattern 8 extends over the via 5. Then, as shown in FIGS. 10 and 11, the conductive pattern 8 is partially embedded in the conductive paste 6 filled in the via 5, so that the surface facing the conductive paste 6 is formed. And both side surfaces thereof are fused to the conductive paste 6. FIG. 10 shows a state in which a plurality of laminated base materials are laminated and integrated by heat fusion, and FIG. 11 shows a state in which a plurality of laminated base materials are laminated using an adhesive 9. Shows a state of being integrated by lamination.
[0050]
Thereby, in the multilayer printed wiring board, the connection reliability between the conductive paste 6 filled in the via 5 and the conductive pattern 8 can be improved.
[0051]
Further, in this multilayer printed wiring board, a part of the conductive pattern 8 is embedded in the conductive paste 6 filled in the via 5, so that the wiring pattern 8 and the conductive paste 6 can be formed without forming a land. Are directly connected to each other, that is, an interlayer connection by a so-called landless structure is possible. Generally, when etching the metal foil 7 after the via 5 is filled with the conductive paste 6, the diameter of the land cannot be smaller than the diameter of the via. Therefore, in this multilayer printed wiring board, by adopting the above-mentioned landless structure, it is possible to further increase the wiring density.
[0052]
In this multilayer printed wiring board, as shown in FIG. 12, the conductive material in the conductive paste 6 is densified by compressing a plurality of laminated base materials in a stacked state.
[0053]
Here, in this method, after filling the via 5 with the conductive paste 6, the diluting solvent and the low molecular weight component of the resin contained in the conductive paste are volatilized and removed. At this time, as shown in FIG. 12, fine voids are generated between the conductive fillers 6a in the conductive paste 6. Then, in the above-described laminating press step, when a plurality of laminated base materials are compressed in the thickness direction in a state of being stacked, the gap between the conductive fillers 6a is narrowed, so that the conductive filler in the conductive paste 6 is reduced. 6a will increase in density. In addition, the density of the conductive filler 6 a in the conductive paste 6 increases as approaching the conductor pattern 8. Furthermore, a difference in hardness occurs in the conductive paste 6 due to a difference in the density of the conductive filler 6 a in the conductive paste 6, and the hardness of the conductive paste 6 increases as approaching the conductive pattern 8. I have.
[0054]
Therefore, in the multilayer printed wiring board, the hardness difference between the conductive paste 6 and the conductive pattern 8 due to the continuous difference (gradation) in the hardness of the conductive paste 6 described above, that is, the conductive pattern 8 Harder than it is relaxed. As a result, stress relaxation to mechanical stress and thermal stress occurs, and impact resistance and connection reliability are remarkably improved.
[0055]
As shown in FIG. 13, the conductor pattern 8 has a width W on the side embedded in the conductive paste 6 in a cross section in the thickness direction thereof. ₁ But the width W on the opposite side ₂ By having a shape narrower than that, the connection reliability with the conductive paste 6 can be further improved.
[0056]
Specifically, the conductor pattern 8 shown in FIG. 12 has a substantially rectangular cross section in the thickness direction. In this case, when the conductive pattern 8 is embedded in the conductive paste 6 filled in the via 5, the surface of the conductive pattern 8 facing the conductive paste 6 pushes away the conductive paste 6, so that the conductive pattern 6 The density of the conductive filler 6a on the side surface does not increase, and it is difficult to fuse the conductive paste 6 to the side surface of the conductor pattern 8.
[0057]
On the other hand, the conductor pattern 8 shown in FIG. 13 has a substantially trapezoidal cross section in the thickness direction. In this case, when the conductive pattern 8 is embedded in the conductive paste 6 filled in the via 5, the surface of the conductive pattern 8 facing the conductive paste 6 gradually displaces the conductive pattern 6 while pushing away the conductive paste 6. The conductive paste 6 is compressed on the side surface. Thus, the density of the conductive filler 6 a on the side surface of the conductor pattern 8 can be increased, and the conductive paste 6 can be fused to the side surface of the conductor pattern 8.
[0058]
Therefore, in this multilayer printed wiring board, the cross-sectional shape of the conductor pattern 8 is changed to the width W on the side embedded in the conductive paste 6. ₁ Is the opposite width W ₂ By making the taper shape narrower than that, the connection reliability between the conductive paste 6 and the conductive pattern 8 can be further improved.
[0059]
In addition, the multilayer printed wiring board to which the present invention is applied may have a configuration in which a conductive pattern 8 is formed on one or both surfaces of the thermoplastic resin film 4 by the conductive paste 6 described above.
[0060]
For example, the multilayer printed wiring boards shown in FIGS. 14 and 15 are the multilayer printed wiring boards shown in FIGS.
[0061]
As shown in FIG. 16, the single-sided wiring base material 10 is finely formed on one surface of the thermoplastic resin film 4 of FIG. 16A by laser processing or drilling a via 5 penetrating in the thickness direction. After forming a groove portion 11 corresponding to the conductor pattern 8 such as a wiring pattern, a land, and a circuit pattern by etching or the like, (k) forming a conductive paste on the via 5 and the groove portion 11 by a printing method, a dispensing method, or the like. 6 by filling.
[0062]
That is, in the single-sided wiring substrate 10, the conductive pattern 6 is filled in the conductive paste 6 by filling the vias 5 and the grooves 11 formed in the thermoplastic resin film 4 with the conductive paste 6. And can be formed integrally.
[0063]
In addition, also with respect to the double-sided wiring base material, similarly to the single-sided wiring base material 10, a groove 11 corresponding to the conductor pattern 8 is formed on both surfaces of the thermoplastic resin film 4, and the conductive paste 6 is filled into the groove 11. It is possible to produce by.
[0064]
Then, the laminated bases composed of the double-sided wiring base 2, the single-sided wiring base 10, and the single-sided wiring base 3 are stacked and integrated by heat fusion in a stacked state. At this time, a laminating press step of sandwiching the laminated base material between the hot plates and compressing in the thickness direction while applying heat and pressure is performed.
[0065]
As a result, the respective layers of the conductor pattern 8 stacked via the thermoplastic resin film 4 are interlayer-connected by the conductive paste 6 filled in the via 5. In addition, since the conductive paste 6 has a lower glass transition point Tg than the thermoplastic resin film 4, when the heating temperature is equal to or higher than the glass transition point Tg of the thermoplastic resin film 4 in the above-described lamination pressing step, The conductive paste 6 is softened, the conductive paste 6 filled in the groove 11 forming the conductive pattern 8 and the conductive paste 6 filled in the via 5 are fused, and the conductive paste filled in the via 5 is fused. The pastes 6 are fused to each other and have no boundaries, and are completely integrated. As described above, this multilayer printed wiring board can be manufactured by laminating all at once.
[0066]
In this multilayer printed wiring board, as described above, by using a thermoplastic resin for the binder of the conductive paste 6, the conductive paste 6 filled in the vias 5 of the thermoplastic resin film 4 and the thermoplastic resin film 4 assures high connection reliability with the conductor pattern 8 formed on one or both surfaces.
[0067]
Further, in this multilayer printed wiring board, by using a thermoplastic resin as a binder of the conductive paste 6 filled in the vias 5 and the grooves 11, stress relaxation to mechanical stress and thermal stress occurs, and the impact resistance is reduced. Performance and connection reliability are significantly improved. Therefore, the connection reliability between conductive paste 6 and conductive pattern 8 can be improved.
[0068]
In this multilayer printed wiring board, as shown in FIG. 17, the conductive pattern 6 is filled in the via 5 by filling the via 5 and the groove 11 formed in the thermoplastic resin film 4 with the conductive paste 6. Since the conductive paste 6 is formed integrally with the conductive paste 6, interlayer connection by the above-described landless structure is possible. By adopting such a landless structure, the wiring density can be further increased.
[0069]
In addition, in the present method, it is possible to manufacture such multilayer printed wiring boards by stacking them all together, and by greatly simplifying the manufacturing process, the productivity of such multilayer printed wiring boards is greatly improved. It is possible.
[0070]
【The invention's effect】
As described in detail above, according to the present invention, when the respective layers of the conductive pattern laminated via the thermoplastic resin film are interconnected by the conductive paste, the binder of the conductive paste is used for the thermoplastic resin. By using, it is possible to easily and obtain high connection reliability.
[0071]
Further, according to the present invention, a plurality of laminated base materials selected from an interlayer connection base material, a single-sided wiring base material, and a double-sided wiring base material are heat-fused in a stacked state or bonded using an adhesive. Therefore, such a multilayer printed wiring board having high connection reliability can be manufactured by laminating all at once, and the productivity can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a manufacturing process of each laminated base material of a multilayer printed wiring board to which the present invention is applied.
FIG. 2 is a cross-sectional view illustrating a multilayer printed wiring board having a four-layer structure, in which a double-sided wiring base, an interlayer connection base, and a double-sided wiring base are laminated and integrated;
FIG. 3 is a cross-sectional view showing a state before the multilayer printed wiring boards shown in FIG. 2 are stacked and integrated.
FIG. 4 is a cross-sectional view illustrating a multilayer printed wiring board having a four-layer structure, in which a double-sided wiring base, a single-sided wiring base, and a single-sided wiring base are laminated and integrated;
5 is a cross-sectional view showing a state before the multilayer printed wiring boards shown in FIG. 4 are stacked and integrated.
FIG. 6 is a cross-sectional view showing a multilayer printed wiring board having a four-layer structure, in which a single-sided wiring base, a double-sided wiring base, and a single-sided wiring base are laminated and integrated.
7 is a cross-sectional view showing a state before the multilayer printed wiring boards shown in FIG. 6 are stacked and integrated.
FIG. 8 is a schematic view showing a state in which a laminated base material is compressed in a thickness direction in a laminating press step.
FIG. 9 is a plan view of a principal part showing a state where a conductive pattern is embedded in a conductive paste filled in vias.
FIG. 10 is a cross-sectional view of a principal part showing a state in which a plurality of laminated base materials are stacked and integrated by thermal fusion in a state of being stacked.
FIG. 11 is a cross-sectional view of an essential part showing a state in which a plurality of laminated base materials are stacked and integrated by bonding using an adhesive in a state of being stacked.
FIG. 12 is a schematic diagram showing a state in which a conductive material in a conductive paste is densified by a conductive pattern having a rectangular cross section.
FIG. 13 is a schematic diagram showing a state where a conductive material in a conductive paste is densified by a conductive pattern having a trapezoidal cross section.
FIG. 14 is a cross-sectional view illustrating a configuration example of a multilayer printed wiring board in which a conductive pattern is formed by using a conductive paste.
15 is a cross-sectional view showing a state before the multilayer printed wiring boards shown in FIG. 14 are stacked and integrated.
FIG. 16 is a cross-sectional view for explaining a manufacturing process of a single-sided wiring base material in which a conductive pattern is formed by using a conductive paste.
FIG. 17 is a plan view of relevant parts showing a state in which a conductive paste is filled into vias and grooves.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Interlayer connection base material, 2 double-sided wiring base materials, 3 single-sided wiring base materials, 4 thermoplastic resin films, 5 vias, 6 conductive pastes, 7 metal foils, 8 conductive patterns, 9
Adhesive, 11 grooves

Claims (19)

An interlayer connection base material filled with a conductive paste obtained by mixing a binder made of a thermoplastic resin and a conductive substance in a hole penetrating an insulating film made of a thermoplastic resin in a thickness direction, and one surface of the above-mentioned interlayer connection base material A single-sided wiring base on which a conductive pattern electrically connected to the conductive paste is formed, and both sides on which a conductive pattern electrically connected to the conductive paste is formed on both sides of the interlayer connecting base The laminated base material selected from the wiring base material is thermally fused or bonded by an adhesive in a state where a plurality of the conductive patterns are stacked so as to be laminated via the insulating film. In addition to being laminated and integrated, the respective layers of the conductor pattern laminated via the insulating film are interconnected by the conductive paste filled in the holes. The printed wiring board. 2. The multilayer printed wiring board according to claim 1, wherein the conductive paste has a lower glass transition point than the insulator film and a lower elastic modulus at the time of fusion than the insulator film. 2. The multilayer printed wiring board according to claim 1, wherein the conductive material in the conductive paste is densified by compressing a plurality of the laminated base materials. 4. The multilayer printed wiring board according to claim 3, wherein the density of the conductive material in the conductive paste increases as the conductive paste approaches the conductive pattern. The conductor pattern is characterized in that a part of the conductive paste is embedded in the conductive paste filled in the hole by being compressed in a state where a plurality of the laminated base materials are stacked. The multilayer printed wiring board according to claim 1. The conductive pattern has a landless structure directly connected to the conductive paste by being partially embedded in the conductive paste filled in the hole. 6. The multilayer printed wiring board according to 5. The side surface portion of the conductive pattern is fused to the conductive paste by being partially embedded in the conductive paste filled in the hole. 6. The multilayer printed wiring board according to 5. 6. The conductive pattern according to claim 5, wherein in a cross section in the thickness direction, a width of a side embedded in the conductive paste is smaller than a width of an opposite side thereof. Multilayer printed wiring board. 2. The multilayer printed circuit board according to claim 1, wherein the conductive pattern is formed on one or both surfaces of the insulating film by the conductive paste. The multilayer printed circuit board according to claim 9, wherein the conductive pattern is formed integrally with the conductive paste filled in the hole. An interlayer connection formed by forming a hole penetrating in the thickness direction through an insulating film made of a thermoplastic resin and filling the hole with a conductive paste obtained by mixing a binder made of a thermoplastic resin and a conductive material. A substrate, a single-sided wiring substrate produced by forming a conductor pattern electrically connected to the conductive paste on one surface of the interlayer connection substrate, and the conductive material on both surfaces of the interlayer connection substrate. A plurality of laminated base materials selected from a double-sided wiring base material produced by forming a conductive pattern electrically connected to the paste so that the conductive pattern is laminated via the insulating film. The layers are laminated and integrated by heat-sealing or bonding using an adhesive in a stacked state, and the respective layers of the conductor pattern laminated through the insulator film are laminated. Method for manufacturing a multilayer printed wiring board for interlayer connection by the been the conductive paste filled in the holes. The method according to claim 11, wherein the conductive paste has a lower glass transition point than the insulator film, and a lower elastic modulus at the time of fusion than the insulator film. Method. The method for manufacturing a multilayer printed wiring board according to claim 11, wherein the conductive material in the conductive paste is densified by compressing the plurality of laminated base materials in a stacked state. The multilayer according to claim 11, wherein a part of the conductive pattern is embedded in the conductive paste filled in the hole by compressing the plurality of the laminated base materials. A method for manufacturing a printed wiring board. By making a part of the conductive pattern buried in the conductive paste filled in the hole, an interlayer connection by a landless structure that directly connects the conductive pattern and the conductive paste is performed. The method for manufacturing a multilayer printed wiring board according to claim 14, wherein: The side face of the conductive pattern is fused to the conductive paste by partially embedding the conductive pattern in the conductive paste filled in the hole. A method for manufacturing the multilayer printed wiring board according to the above. When the conductor pattern is formed on one or both surfaces of the insulator film, in a cross-section in the thickness direction, the width on the side embedded in the conductive paste is smaller than the width on the opposite side. The method for manufacturing a multilayer printed wiring board according to claim 14, wherein: The method according to claim 11, wherein the conductive pattern is formed on one or both surfaces of the insulating film by using the conductive paste. 19. The method according to claim 18, wherein the conductive pattern is formed integrally with the conductive paste filled in the hole.

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