JP2009060015A - Solid printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting configuration capable of easily actualizing size reduction, height reduction, and three-dimensional mounting adaptive to high-function/multi-pin configurations of a semiconductor needed to make mobile equipment compact, thin, lightweight, highly fine, multifunctional, etc. <P>SOLUTION: The solid printed circuit board 15 has: a plurality of printed circuit boards in different shapes having wirings formed in surface layers; and a connection layer 3 which connects the printed circuit boards to one another and is 30 to 300 μm thick. The connection layer 3 is composed of an insulating layer formed by dispersing an inorganic filler and an elastomer component in thermosetting resin and has a via hole 7 formed by boring a through hole 9 in the insulating layer at a predetermined position and charging conductive paste 6 in the through hole 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a three-dimensional printed wiring board widely used in various electronic devices such as a personal computer, a mobile communication telephone, and a video camera.

  Recently, personal computers, digital cameras, mobile phones, etc. have become widespread as mobile products. Especially, there are strong demands for small size, thinness, light weight, high definition, multi-functionality, etc.・ Low profile and 3D mounting are progressing. A method using a cavity substrate is known as one method for easily realizing such a low-profile and three-dimensional mounting of a semiconductor package.

  Hereinafter, a conventional cavity substrate will be described with reference to FIG.

  In FIG. 8, the lower printed wiring board 22 and the upper printed wiring board 23 are overlapped while aligning the positions of the electrodes and the windows with the connection layer 21 made of a thermosetting resin in between. Then, the multilayer printed wiring board 27 provided with the hollow for embedding an electronic component is formed by thermocompression bonding.

For example, Patent Document 1 is known as prior art document information related to the application of the present invention.
JP 2004-253774 A

  In the conventional multilayer printed wiring board as shown in FIG. 8, the connection layer generally made of a thermosetting resin is once melted and hardened due to the temperature rise at the time of lamination with the upper and lower printed wiring boards. The stress becomes zero at the temperature at which close contact is obtained. After cooling, the behavior of thermal shrinkage between the connection layer and the upper and lower printed wiring boards is different, so internal stress is applied between them, and the problem that warpage occurs in the completed multilayer printed wiring board Had.

  The present invention has been made in view of the above problems, and provides a three-dimensional printed wiring board capable of connecting multiple pins between substrates and increasing the wiring density in the substrate.

  In order to achieve the above object, the present invention includes a plurality of printed wiring boards having different shapes in which wiring is formed on a surface layer, and a connection layer having a thickness of 30 to 300 μm that connects between the printed wiring boards, The connection layer is made of an insulating layer in which an inorganic filler and an elastomer component are dispersed in a thermosetting resin. A through hole is formed in a predetermined position of the insulating layer, and the via is filled with a conductive paste. It is a three-dimensional printed wiring board characterized by having.

  By adopting such a configuration, the fluidity of the inorganic filler is suppressed, and the inorganic filler has a thermal expansion that is about 1/10 lower than that of the resin. Therefore, the temperature during lamination is higher than the printed wiring boards above and below the insulating layer. Small dimensional variation due to ascent. Therefore, the upper and lower printed wiring boards are in close contact with the internal stress while the shape is regulated by the press pressure at high temperatures, but when the temperature returns to room temperature, the stress is released and warping is reduced as if it were bonded at room temperature. Therefore, it is possible to connect multiple pins between boards, increase the wiring density in the board, and further have recesses, so that a thin printed wiring board can be realized by mounting components in the recesses. be able to.

  As described above, the present invention enables multi-pin connection between substrates and increases the wiring density in the substrate, so that the mobile device is small, thin, lightweight, high-definition, multifunctional, etc. Therefore, it is possible to provide a mounting form that can easily realize a small size, a low profile, and a three-dimensional mounting corresponding to the high-functionality and multi-pin semiconductors necessary for realizing the above.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view and a cross-sectional view of a three-dimensional printed wiring board according to an embodiment of the present invention. The three-dimensional printed wiring board of the present embodiment is composed of an upper printed wiring board 1 having a wiring formed on the surface layer and different shapes, a lower printed wiring board 2, and a connection layer 3 having a thickness of 30 to 300 μm. Since the printed wiring board 1 and the lower printed wiring board 2 have different shapes, a recess 4 serving as a cavity is formed as shown in FIG.

  As shown in FIG. 1B, by mounting the mounting component 5 in the recess 4, the total thickness of the mounting body can be reduced.

  An enlarged sectional view of the connection layer 3 in the present invention is shown in FIG. The connection layer 3 of the present invention is composed of an insulating layer in which an inorganic filler and an elastomer component are dispersed in a thermosetting resin such as an epoxy resin, and through holes 9 are formed at predetermined positions of the insulating layer. The hole 9 has a via 7 filled with a conductive paste 6. The connection layer 3 does not include a core material such as a woven fabric, a nonwoven fabric, or a film.

  In the present invention, the inorganic filler in the insulating layer is preferably composed of at least one of silica, alumina, and barium titanate. Moreover, it is preferable that the particle size of the inorganic filler in an insulating layer is 1-15 micrometers, and the content rate of an inorganic filler is 70-90 weight%. If the content of the inorganic filler is less than 70%, the amount of the inorganic filler that forms the connection layer 3 is less than the amount of the thermosetting resin, and is in a rough state, and the thermosetting resin flows during the press. At the same time, the inorganic filler also flows, and if it exceeds 90%, the amount of the resin of the connection layer 3 becomes too small, and the embeddability and adhesion of the wiring are impaired, which is inappropriate.

  Further, the elastomer component in the present invention is composed of either an acrylic elastomer or a thermoplastic elastomer. Specifically, for example, polybutadiene or butadiene-based random copolymer rubber or a copolymer having a hard segment and a soft segment is used. The content of the elastomer component is preferably 0.2 to 5.0% by weight with respect to the total amount of the epoxy resin composition.

  In the present invention, since the inorganic filler and the elastomer component are dispersed in the thermosetting resin constituting the connection layer 3, the elastomer component is segregated on the surface of the inorganic filler, thereby further suppressing the fluidity of the inorganic filler. it can.

  The conductive paste 4 used for the printed wiring board of the present invention is composed of copper, silver, gold, palladium, bismuth, tin, and alloys thereof, and preferably has a particle size of 1 to 20 μm.

  Next, the manufacturing process of the three-dimensional printed wiring board of this Embodiment is demonstrated in detail using FIG.

  First, as shown in FIG. 2A, the PET film 8 is attached to both surfaces of the connection layer 3. Next, as shown in FIG. 2 (B), the connection layer 3 is cut into the shape of the upper printed wiring board 1, and the through hole 9 is formed at a position where the wiring of the upper printed wiring board 1 and the lower printed wiring board 2 are connected. Form. Next, as shown in FIG. 2C, the through-hole 9 is filled with a conductive paste 6 made of copper or a copper alloy, and a via 7 is formed. Next, as shown in FIG. 2D, in order to bond the connection layer 3 to either the upper printed wiring board 1 or the lower printed wiring board 2, the PET film 8 on one surface is peeled off. Here, the lower PET film 8 is peeled off in order to adhere to the lower printed wiring board 2 first, but the upper PET film 8 may be peeled off first. At this time, if the PET films 8 on both sides are peeled at the same time, the uncured connection layer 3 tends to be crushed, making it difficult to handle. Therefore, in this embodiment, the PET film 8 on either side is peeled off.

  Next, as shown in FIG. 3A, the connection layer 3 is disposed at a desired position on the lower printed wiring board 2, and the conductive paste 6 is placed on the lower printed wiring as shown in FIG. Lamination is performed while heating and pressing on the wiring 10 formed on the plate 2. The wiring 10 is embedded in the connection layer 3 during this lamination. By doing so, the conductive paste 6 is further compressed, so that the connectivity with the wiring 10 is greatly improved. Thereafter, as shown in FIG. 3C, the PET film 8 on the surface that has not been peeled first is peeled off.

  Next, as shown in FIG. 4A, the upper printed wiring board 1 is disposed on the connection layer 3, and as shown in FIG. 3D printed wiring board 15 is completed.

  The wiring 10 is embedded in the connection layer 3 during this lamination. By doing so, the conductive paste 6 is further compressed in the same manner as in FIG. 3B, so that the connectivity with the wiring 10 is greatly improved.

  Since the inorganic filler and the elastomer component are dispersed in the thermosetting resin constituting the connection layer 3, the fluidity of the inorganic filler is suppressed, and the inorganic filler has a lower thermal expansion than the resin. The layer 3 has less dimensional variation due to temperature rise than the upper and lower printed wiring boards. Therefore, the upper and lower printed wiring boards are in close contact with the internal stress while the shape is regulated by the press pressure at a high temperature. However, when the three-dimensional printed wiring board 15 is formed after returning to room temperature, the stress is released and warping occurs. Reduced.

  In general, in the case of a structure having a dent, that is, a recess, dust, base powder, and the like are easily collected in the corner of the recess. In the case of a smooth printed wiring board having no recess, dust and powder were easily removed with a dust-removing adhesive roll, but it was difficult to remove the corner portion of the recess with the adhesive roll.

  Therefore, in order to prevent dust and powder from entering the recess 4, powder scattering to the recess 4 of the upper printed wiring board 1, lower printed wiring board 2 and connection layer 3, dust to the recess 4, etc. 5, a dry film-like permanent resist 11 having a thickness of 5 to 30 μm is pasted as shown in FIG. 5, and an upper printed wiring board 1 and a lower printed wiring board 2 are attached. It is more preferable for the three-dimensional printed wiring board of the present invention to cover the wall surface of the connection layer 3. As a result, it is possible to prevent the powder or dust from adhering to the corners of the recess 4 in particular. If the thickness of the permanent resist 11 is less than 5 μm, pinholes are likely to be generated, so that the coating is insufficient, and if it exceeds 30 μm, the followability to the substrate is deteriorated, which is inappropriate.

  The thermal expansion coefficient of the connection layer 3 of the present invention is equal to or lower than the thermal expansion coefficient of the upper printed wiring board 1 and the lower printed wiring board 2, that is, 4 to 65 ppm / ° C. or lower than the thermal expansion coefficient of the printed wiring board. desirable.

  If it is less than 4 ppm / ° C., it is inappropriate because it is smaller than the thermal expansion coefficient of the mounting component 5 such as silicon. When it exceeds 65 ppm / ° C. or higher than the thermal expansion coefficient of the upper printed wiring board 1 and the lower printed wiring board 2, the connection layer 3 is easily deformed, and the three-dimensional printed wiring board is likely to be warped or deformed. It is inappropriate.

  Further, the glass transition point of the connection layer 3 (DMA method Dynamic Mechanical Analysis (dynamic viscoelasticity measurement method)) is 185 ° C. or higher or higher by 10 ° C. or more than the upper printed wiring board 1 and the lower printed wiring board 2. It is desirable. If the temperature is less than 185 ° C. or the difference is less than 10 ° C., the conductive paste 6 starts to harden and the connection layer 3 is easily melted during lamination before the shape can be maintained. As a result, a via flow is likely to occur. So it is inappropriate.

  Moreover, the connection layer 3 uses the structure which does not contain core materials, such as a woven fabric, a nonwoven fabric, and a film. When the core material is included, it is inappropriate because it is difficult to embed wiring patterns formed on the upper and lower printed wiring board surfaces as described above.

  The minimum melt viscosity of the connection layer 3 is suitably 1000 to 100,000 Pa · s as shown in the melt viscosity curve of FIG. If the pressure is less than 1000 Pa · s, the resin flow becomes large and may flow into the recess 4. If the pressure exceeds 100000 Pa · s, poor adhesion to the printed wiring board or poor embedding in the wiring 10 occurs. It is inappropriate because there is a risk.

  The connection layer 3 may contain a colorant. In this case, mountability and light reflectivity are improved.

  Further, since it is necessary to suppress the resin flow of the connection layer 3, that is, to prevent the resin from flowing into the recess 4, a release sheet having a melting temperature lower than the melting temperature of the connection layer 3 is used. To prevent the flow of resin during pressing.

  The upper printed wiring board 1 and the lower printed wiring board 2 are not particularly limited as long as they are resin substrates such as through-hole wiring boards and all-layer IVH-structured ALIVH wiring boards. It may be a multilayer substrate. Also, a plurality of printed wiring boards and connection layers may be laminated alternately.

  The insulating material used for the upper printed wiring board 1 and the lower printed wiring board 2 is a composite material of glass woven fabric and epoxy resin, but organic fiber and glass fiber selected from aramid and wholly aromatic polyester, alumina In the case of a composite material of a woven fabric composed of any one of inorganic fibers selected from fibers and a thermosetting resin, p-aramid, polyimide, poly-p-phenylenebenzobisoxazole, wholly aromatic polyester, A case where it is composed of a composite material of a non-woven fabric and a thermosetting resin composed of any one of organic fibers and glass fibers selected from PTFE, polyether sulfone, polyether imide, and inorganic fibers selected from alumina fibers; and p-aramid, Poly-p-phenylene benzobisoxazole, wholly aromatic polyester, polyether imi , Polyetherketone, Polyetheretherketone, Polyethylene terephthalate, Polytetrafluoroethylene, Polyethersulfone, Polyester terephthalate, Polyimide and polyphenylene sulfide An insulating material may be formed using a material.

  As the thermosetting resin, at least one thermosetting resin selected from an epoxy resin, a polybutadiene resin, a phenol resin, a polyimide resin, a polyamide resin, and a cyanate resin can be used.

  In the present embodiment, the shape of the upper printed wiring board has been described as a floating island shape having a smaller outer frame than the lower printed wiring board 2 as shown in FIG. 1, but the outer frame has a shape as shown in FIG. The concave portion 4 may be formed by hollowing out an arbitrary portion of the upper printed wiring board 1 with the same shape.

  The three-dimensional printed wiring board according to the present invention can be formed with a thin total board thickness as a mounting body after component mounting, so that it is small, thin, lightweight, high definition, multifunctional such as a personal computer, a digital camera, a mobile phone, etc. It can be used as a package substrate for dealing with the above and the like, and can be applied to applications related to these mounting substrates as one of the methods for easily realizing a low-profile and three-dimensional mounting of a semiconductor package.

The perspective view and sectional drawing which show an example of the three-dimensional printed wiring board in Embodiment 1 of this invention Manufacturing process sectional drawing of the three-dimensional printed wiring board in Embodiment 1 of this invention Manufacturing process sectional drawing of the three-dimensional printed wiring board in Embodiment 1 of this invention Manufacturing process sectional drawing of the three-dimensional printed wiring board in Embodiment 1 of this invention Sectional drawing which shows an example of the three-dimensional printed wiring board in Embodiment 1 of this invention The figure which shows the melt viscosity of the connection layer of the three-dimensional printed wiring board in Embodiment 1 of this invention The perspective view and sectional drawing which show an example of the three-dimensional printed wiring board in Embodiment 1 of this invention Sectional view of a conventional printed wiring board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper side printed wiring board 2 Lower side printed wiring board 3 Connection layer 4 Recessed part 5 Mounting component 6 Conductive paste 7 Via 8 PET film 9 Through-hole 10 Wiring 11 Permanent resist 15 Three-dimensional printed wiring board

Claims (13)

A plurality of printed wiring boards having different shapes in which wiring is formed on the surface layer, and a connection layer having a thickness of 30 to 300 μm that connects between the printed wiring boards, the inorganic filler and the elastomer component being heated by the connection layer A three-dimensional printed wiring board comprising an insulating layer dispersed in a curable resin, a through hole formed in a predetermined position of the insulating layer, and a via filled with a conductive paste in the through hole . The three-dimensional printed wiring board according to claim 1, wherein the inorganic filler in the connection layer is made of at least one of silica, alumina, and barium titanate. The three-dimensional printed wiring board according to claim 1, wherein the content of the inorganic filler in the connection layer is 70 to 90% by weight. The three-dimensional printed wiring board according to claim 1, wherein the elastomer component in the connection layer is made of either an acrylic elastomer or a thermoplastic elastomer, and the content is 0.2 to 5.0 wt%. The three-dimensional printed wiring board according to claim 1, wherein the thermosetting resin in the connection layer is made of an epoxy resin. The three-dimensional printed wiring board of Claim 1 whose particle size of the inorganic filler in a connection layer is 1-15 micrometers. 2. The three-dimensional printed wiring board according to claim 1, wherein a thermal expansion coefficient at a temperature below the glass transition point of the connection layer is 4 to 65 ppm / ° C. or lower than a thermal expansion coefficient of the printed wiring board. The three-dimensional printed wiring board according to claim 1, wherein the glass transition point (DMA method) of the connection layer is 185 ° C or higher or 10 ° C or higher than the glass transition point of the printed wiring board. The three-dimensional printed wiring board according to claim 1, wherein the connection layer does not include a core material. The three-dimensional printed wiring board according to claim 1, wherein the minimum melt viscosity of the connection layer is 1000 to 100,000 Pa · s. The three-dimensional printed wiring board according to claim 1, wherein the connection layer and the wall surface of the printed wiring board are covered with an insulating film having a thickness of 5 to 30 μm. The three-dimensional printed wiring board according to claim 11, wherein the insulating coating contains an antistatic agent. The three-dimensional printed wiring board according to claim 1, wherein the connection layer contains a colorant.

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