JP4135384B2 - Printed wiring board - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a printed wiring board bonded and integrated with a heat slug.
[0002]
[Prior art]
Conventionally, as a printed wiring board, there is one in which a heat slug 8 is bonded to a back surface side of a wiring board 5 with a resin adhesive 7 as shown in FIG.
The wiring substrate 5 is obtained by forming the conductor pattern 3 on the surface of the insulating substrate 1. In the center of the insulating substrate 1, a mounting portion 19 for mounting the electronic component 6 is provided. The electronic component 6 is bonded to the surface of the heat slug 8 constituting the bottom surface of the mounting portion 19 with an adhesive 69. The electronic component 6 is electrically connected to the conductor pattern 3 by a bonding wire 62.
Here, as the insulating substrate 1 and the resin adhesive 7 for heat slag adhesion, conventionally, a thermosetting resin has been used.
[0003]
[Problems to be solved]
However, in the above-described conventional printed wiring board, the thermosetting resin used as the insulating substrate 1 and the resin adhesive 7 for heat slag bonding has a property of being cured at a high temperature. For this reason, even if the printed wiring board is exposed to a high temperature, the insulating substrate 1 and the resin adhesive 7 do not melt. Therefore, the insulating substrate 1 cannot be reused after being melted, remolded. Further, since the resin adhesive 7 does not melt, the heat slag 8 cannot be peeled off from the insulating substrate 1 and it is difficult to separate the heat slag from the wiring board.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a printed wiring board that can separate a heat slug and a wiring board and can be reused.
[0005]
[Means for solving problems]
The present invention is a printed wiring board comprising a wiring board comprising a resin part and a conductor part, and a heat slug, wherein the heat slug is adhered to the resin part of the wiring board by a resin adhesive.
The resin part and the resin adhesive are made of a thermoplastic resin having a heat deformation temperature of 240 ° C. or higher,
The printed wiring board is characterized in that the melting point of the resin adhesive is lower than the melting point of the resin portion.
[0006]
In the present invention, a thermoplastic resin is used as the insulating substrate and the resin adhesive. Since the thermoplastic resin has a linear structure mainly in a linear structure, it melts when heated, solidifies when cooled, and can be repeatedly melted and solidified by heating and cooling. Here, “melting” refers to a phase change in which a substance in a solid phase is heated to become a liquid phase.
The melting point of the resin adhesive is lower than the melting point of the resin part. For this reason, the printed wiring board can be reused by setting the heating temperature in two stages.
[0007]
That is, first, the printed wiring board is heated at a temperature higher than the melting point of the resin adhesive for heat slag bonding and lower than the melting point of the resin portion of the wiring board. Accordingly, the resin adhesive is melted without melting the resin portion, and the heat slug can be peeled off from the wiring board.
Next, the heating temperature is raised, and the wiring board is heated at a temperature higher than the melting point of the resin part of the wiring board and lower than the melting point of the conductor part. Thereby, the resin part can be melted without melting the conductor part, and the resin part and the conductor part can be separated.
In addition, the separated heat slug, conductor portion, and resin portion can be reused.
The resin adhesive and the resin portion of the wiring board both have a heat deformation temperature of 240 ° C. or higher. For this reason, it can suppress that a resin adhesive and a resin part deform | transform in the case of manufacture and use of a printed wiring board.
[0008]
As described above, according to the present invention, it is possible to provide a printed wiring board that can separate the heat slug and the wiring board and can be reused.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The thermal deformation temperature of the thermoplastic resin used in the resin part of the wiring board and the resin adhesive for heat slag is 240 ° C. or higher. Printed wiring boards may be heated during manufacture and use. Also in this case, if the thermal deformation temperature of the thermoplastic resin is 240 ° C. or higher, the insulating substrate is not deformed. On the other hand, if it is less than 240 ° C., the printed wiring board may be deformed during manufacture and use.
The heat distortion temperature is a numerical value obtained by a load deflection temperature test according to the test method ASTM D648.
[0010]
The melting point of the resin adhesive must be lower than the melting point of the resin part of the wiring board. If the melting point of the resin adhesive is higher than the melting point of the resin part, when the resin adhesive is melted, the resin part of the wiring board will melt, making it difficult to remove the heat slug from the wiring board. is there.
The melting point refers to the temperature at which a solid phase substance maintains equilibrium with the liquid phase under a pressure of 1 atm.
[0011]
It is desirable that the thermoplastic resin used for the resin adhesive and the resin portion does not deform without load at 260 ° C. for 1 minute. Thereby, the deformation | transformation of the printed wiring board at the time of manufacture and use can be suppressed further.
In the present invention, the wiring board includes a conductor portion and a resin portion. The conductor part is composed of a conductor pattern, a via hole, or the like. The resin portion is made of a resin insulating substrate, a solder resist, or the like.
As the heat slag, it is preferable to use a material having good thermal conductivity, and examples thereof include Cu, Ni, Al, Ag, C, AlN, and SiC materials.
[0012]
Examples of combinations of the resin adhesive and the resin part are as follows.
That is, it is preferable that the resin adhesive is made of polyamide, and the resin portion is made of polyamideimide. Polyamide (filled with 30% Glass fiber) has a heat deformation temperature of 251 ° C. and a melting point of 265 ° C., for example, and polyamideimide has a heat deformation temperature of 282 ° C. and a melting point of 300 ° C., for example.
[0013]
【Example】
(Example 1)
A printed wiring board according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the printed wiring board of this example includes a wiring board 5 and a heat slug 8. The heat slug 8 is bonded to the wiring board 5 with a resin adhesive 7. The wiring substrate 5 includes a resin insulating substrate 1 as a resin portion and a conductor pattern 3 as a conductor portion.
The resin insulating substrate 1 and the resin adhesive 7 of the wiring substrate 5 are made of a thermoplastic resin having a heat deformation temperature of 240 ° C. or higher. The melting point of the resin adhesive 7 is lower than the melting point of the resin insulating substrate 1.
[0014]
In this example, the thermoplastic resin used for the resin insulating substrate 1 is a polyamideimide having a heat deformation temperature of 282 ° C. and a melting point of 300 ° C., and the resin adhesive 7 is a polyamide (Glass Glass having a heat deformation temperature of 251 ° C. and a melting point of 265 ° C. Fiber 30% filling). The Glass Fiber filled here is REF015 manufactured by Nippon Sheet Glass Co., Ltd. The resin insulating substrate 1 has a length of 42.5 mm, a width of 42.5 mm, and a thickness of 0.5 mm, and the heat slug 8 has a length of 41.1 mm, a width of 41.1 mm, and a thickness of 0.5 mm.
[0015]
A mounting portion 19 for mounting the electronic component 6 is formed at a substantially central portion of the resin insulating substrate 1. The bottom part of the mounting part 19 is composed of a heat slug 8, and the electronic component 6 is bonded thereto via an adhesive 69. The electronic component 6 is electrically connected to the conductor pattern 3 by a bonding wire 62.
[0016]
When the printed wiring board is manufactured, as shown in FIG. 2, the conductive insulating pattern 1 and the conductive pattern 3 are formed in the resin insulating substrate 1 made of a thermoplastic resin by forming the mounting hole forming holes 13 mm in length and 13 mm in width. Thus, the wiring board 5 is obtained. Next, the resin insulating substrate 1 side of the wiring substrate 5 is opposed to the heat slug 8, and both are laminated with the resin adhesive 7 interposed therebetween. These are pressure-bonded at a heating temperature of 265 ° C. and a pressure of 0.2 MPa for 20 minutes. At this time, the thermoplastic resin constituting the resin adhesive 7 is melted. Thereafter, the resin adhesive 7 is solidified by returning to room temperature, and the heat slag 8 and the resin insulating substrate 1 are bonded.
Thus, the printed wiring board of this example is obtained.
[0017]
In reusing the printed wiring board of this example, first, the printed wiring board was heated at 265 ° C. for 10 minutes. Thereby, it was confirmed that the resin insulating substrate 1 and the heat slag 8 can be completely separated, and no resin pieces or the like remain on the surface of the heat slag after the separation.
[0018]
Next, the heating temperature was raised and the wiring board 5 was heated. Thereby, the resin insulating substrate 1 can be melted without melting the conductor pattern 3, and the resin insulating substrate 1 can be separated from the conductor pattern 3.
Also, the printed wiring board did not undergo thermal deformation during manufacture and use.
[Brief description of the drawings]
1 is a cross-sectional view of a printed wiring board of Example 1. FIG.
[Explanation of symbols]
1. . . Resin insulation substrate,
19. . . Mounting part,
3. . . Conductor pattern,
5. . . Wiring board,
6). . . Electronic components,
7). . . Resin adhesive,
8). . . Heat slug,

Claims (2)

A printed wiring board comprising a wiring board composed of a resin part and a conductor part, and a heat slug, wherein the heat slug is bonded to the resin part of the wiring board by a resin adhesive.
The resin part and the resin adhesive are made of a thermoplastic resin having a heat deformation temperature of 240 ° C. or higher,
The printed wiring board, wherein the melting point of the resin adhesive is lower than the melting point of the resin part.   2. The printed wiring board according to claim 1, wherein the resin adhesive is made of polyamide, and the resin portion is made of polyamideimide.

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