JP4095354B2 - Metal substrate and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal substrate in which a metal plate and a printed wiring board are bonded together with an adhesive.
[0002]
[Prior art]
Conventionally, as a method of adhering a metal plate and a printed wiring board, for example, as disclosed in Japanese Patent Application Laid-Open No. 05-259650, an adhesive sheet is sandwiched between the metal plate and the printed wiring board, and then applied by heating and pressing. The matching technology is widely known. As shown in FIG. 7, such a metal substrate sandwiches a semi-curable adhesive sheet (prepreg) or the like between the metal plate 1 and the printed wiring board 3 having the conductive pattern 4 and the through hole 5. It was formed by heating and pressing.
[0003]
[Problems to be solved by the invention]
In the above conventional method for manufacturing a metal substrate, a thick adhesive layer 2 is required to absorb irregularities and warpage on the surface of the printed wiring board 3, and the adhesive is provided on the printed wiring board 3 during heating and pressing. There is a problem that the conductive pattern 4 is contaminated by reaching the back surface (20a in FIG. 7) through the through-hole 5 formed. In addition, the adhesive protrudes from the end face of the metal substrate (20b in FIG. 7), and there is a problem that the outer size varies.
[0004]
When the metal substrate is used for high frequency applications, the adhesive is required to have conductivity and high heat dissipation, and the adhesive layer 2 between the conductor pattern 4 of the printed wiring board 3 and the metal plate 1 needs to be thin. There is a problem that the warp and unevenness of the printed wiring board 3 cannot be absorbed, the adhesive does not sufficiently flow into the recess, and the adhesive is not bonded between the recess and the metal plate.
[0005]
The present invention has been made to solve the above-mentioned problems, and prevents the adhesive that bonds the metal plate and the printed wiring board from sticking out from the substrate and poor adhesion, and also provides conductivity and high heat dissipation. The purpose is to reduce the thickness of the adhesive at the part where the property is required.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for manufacturing a metal substrate in which a metal plate and a printed wiring board disposed on one or both main surfaces of the metal plate are integrated with an adhesive. A printed wiring board printed with an adhesive and a metal plate printed with an adhesive on the entire surface of one main surface or both main surfaces are bonded together.
[0007]
According to a second aspect of the present invention, there is provided a metal substrate manufacturing method in which a metal plate and a printed wiring board disposed on one or both main surfaces of the metal plate are integrated with an adhesive, and formed on the printed wiring board. a surface excluding the conductive portion of the heat radiation portion and the metal plate conductor pattern was coated with resist, and printing the conductive adhesive on the conductive portion of the heat radiation portion and the metal plate of the printed wiring board, the conductive characterized in that the adhesive printed printed circuit board and the whole surface of the bonding the conductive metal plate where the adhesive is printed.
[0008]
The invention of claim 3 is an adhesive according to the invention of claim 1, in which the height of the recessed portion excluding the conductor pattern of the printed wiring board is higher than the conductor pattern and a gap is formed between the conductor pattern and the adhesive. The volume of the adhesive protruding from the conductor pattern is the same as the volume of the gap.
[0009]
The invention of claim 4 is a metal substrate in which a metal plate and a printed wiring board disposed on one or both main surfaces of the metal plate are integrated with an adhesive, and the conductor pattern of the printed wiring board is removed. A non-conductive adhesive is formed between the recess and the metal plate, and a conductive adhesive is formed between the conductor pattern of the printed wiring board and the metal plate.
[0010]
The invention of claim 5 includes a metal plate, in the manufacturing method of the metal substrate to be integrated by the adhesive printed wiring board which is arranged on one main surface or both main surfaces of the metal plate, the conductor pattern of the printed wiring board A printed wiring board printed with a non-conductive adhesive in the removed recess and a metal plate printed with a conductive adhesive on the entire surface excluding the portion facing the non-conductive adhesive .
[0011]
The invention according to claim 6 is a metal substrate in which a metal plate and a printed wiring board disposed on one or both main surfaces of the metal plate are integrated with an adhesive, and the conductor pattern of the printed wiring board is removed. A heat conductive adhesive is formed between the recess and the metal plate, and a conductive adhesive is formed between the conductor pattern of the printed wiring board and the metal plate.
[0012]
The invention of claim 7, a metal plate, in the manufacturing method of the metal substrate to be integrated by the adhesive printed wiring board which is arranged on one main surface or both main surfaces of the metal plate, the recess except for conductor patterns It is characterized in that a printed wiring board printed with a heat conductive adhesive and a metal plate printed with a conductive adhesive on the entire surface excluding a portion facing the heat conductive adhesive are bonded together.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a metal substrate manufacturing process according to Embodiment 1 of the present invention. Hereinafter, a method of attaching a metal plate and a printed wiring board with an adhesive will be described with reference to FIG.
[0015]
First, as shown in FIGS. 1A and 1B, an adhesive 2 a is printed on the metal plate 1. Here, the adhesive 2a is applied to the metal plate 1 by screen printing so as to have a thickness in consideration of the thermal resistance from the conductor pattern 4 of the printed wiring board 3 to the metal plate 1 to be described later, for example, 10 to 50 μm. To form.
[0016]
On the other hand, as shown in FIG. 1C, the printed wiring board 3 has conductor patterns 4 formed on the front and back surfaces thereof. When the printed wiring board 3 is, for example, a high-frequency board, the conductor pattern 4 has a large number of through holes 5 for connection to the ground in order to ensure high-frequency characteristics. In addition, gold plating is applied to the outermost layer of the conductor pattern 4 for solder connection of the component parts.
[0017]
FIG. 1 (d) shows a diagram in which an adhesive 2 b is applied to the printed wiring board 3, and the adhesive 2 b here is applied only to a portion 6 of the printed wiring board 3 excluding the conductor pattern 4 by screen printing. . At this time, the thickness of the adhesive 2b to be applied is larger than the height of the conductor pattern 4, and printing is performed so that a gap is formed between the conductor pattern 4 and the adhesive 2b.
[0018]
Next, as shown in FIG. 1 (e), the metal plate 1 coated with the adhesive 2a and the printed wiring board 3 coated with the adhesive 2b are bonded together, as shown in FIG. 1 (f). Then, a weight of 0.1 kgf / cm ² is applied to the adhesive ² by the weight 7 and the adhesive is cured at room temperature to 175 ° C. for about 1 hour to 12 hours.
[0019]
As described above, according to the first embodiment, the adhesive surface pressure on the entire surface between the metal plate 1 and the printed wiring board 3 becomes substantially uniform, and the adhesive 2 is partially from the end surface of the printed wiring board 3. This prevents the adhesive 2 from short-circuiting the conductive pattern 4 on the surface of the printed wiring board 3 through the through-hole 5, and also prevents the adhesive 6 from remaining in the portion 6 of the printed wiring board 3 excluding the conductive pattern 4. The occurrence of adhesion can also be prevented.
[0020]
In addition, since the protrusion of the slight amount of the adhesive 2 due to the adhesive surface pressure can be retreated into the gap between the conductor pattern 4 and the adhesive 2, the adverse effect due to the protrusion can be prevented. Usually, the conductive pattern 4 is inferior in adhesiveness with the adhesive 2 because the outermost layer is gold plating, but by adhering to the portion 6 excluding the conductive pattern 4, good overall adhesiveness can be secured. .
[0021]
Embodiment 2. FIG.
FIG. 2 is a cross-sectional view showing a metal substrate manufacturing process according to Embodiment 2 of the present invention. Hereinafter, a method for attaching a metal plate and a printed wiring board with an adhesive will be described with reference to FIG.
[0022]
First, as shown in FIGS. 2A and 2B, an adhesive 2 a is printed on the metal plate 1. Here, the adhesive 2a is applied to the metal plate 1 by screen printing so as to have a thickness in consideration of the thermal resistance from the conductor pattern 4 of the printed wiring board 3 to the metal plate 1 to be described later, for example, 10 to 50 μm. To form.
[0023]
On the other hand, as shown in FIG. 2 (c), the printed wiring board 3 has conductor patterns 4 formed on the front and back surfaces. When the printed wiring board 3 is a high-frequency substrate, for example, the conductive pattern is used to ensure high-frequency characteristics. A number of through holes 5 for connecting to the ground are formed in 4. Further, a portion other than the heat dissipation / conduction portion 9 of the conductor pattern 4 is covered with a resist 8, and only the heat dissipation / conduction portion 9 of the conductor pattern 4 is plated with gold.
[0024]
Then, as shown in FIG. 2 (d), the adhesive 2 is printed by screen printing only on the heat radiation / conduction portion 9 of the conductor pattern 4. At this time, the thickness of the adhesive 2 is larger than the height of the resist 8, and printing is performed so that a gap is formed between the resist 8 and the adhesive 2.
[0025]
Thereafter, as shown in FIGS. 2 (e) and 2 (f), the metal plate 1 coated with the adhesive 2 a and the printed wiring board 3 coated with the adhesive 2 b are bonded to each other with a weight 7. A load of 1 kgf / cm ² is applied to the adhesive 2 and the adhesive is cured at room temperature to 175 ° C. for about 1 to 12 hours.
[0026]
As described above, according to the second embodiment, the adhesive surface pressure on the entire surface between the metal plate 1 and the printed wiring board 3 becomes substantially uniform, and the adhesive 2 does not partially protrude. 2 prevents the conductor pattern 4 on the surface of the printed wiring board 3 from being short-circuited through the through-hole 5, and non-adhesion occurs between the heat dissipation / conduction portion 9 of the printed wiring board 3 and the metal plate 1. Can be prevented.
[0027]
In addition, since a slight amount of the adhesive 2 protruding due to the adhesive surface pressure can be retreated into the gap between the resist 8 and the adhesive 2b, the above-described adverse effects due to the protrusion can be prevented. Usually, the heat dissipation / conduction portion 9 is inferior in adhesion to the adhesive 2 because the outermost layer is gold-plated, but by adhering to the resist 8, good adhesion can be ensured as a whole.
[0028]
Embodiment 3 FIG.
FIG. 3 is a cross-sectional view showing a metal substrate manufacturing process according to Embodiment 3 of the present invention. Hereinafter, a method of attaching a metal plate and a printed wiring board with an adhesive will be described with reference to FIG.
[0029]
First, as shown in FIGS. 3A and 3B, an adhesive 2 a is printed on the metal plate 1. Thereafter, as shown in FIG. 3 (c), on the adhesive 2a of the metal plate 1, for example, a restraining plate 10 to which an adhesive 2a typified by a Teflon substrate (Teflon is a registered trademark) hardly adheres is placed. The weight 11 is mounted on the surface to flatten the surface of the adhesive 2a.
[0030]
On the other hand, as shown in FIGS. 3D and 3E, an adhesive 2b is applied to the portion 6 of the printed wiring board 3 excluding the conductor pattern 4 by screen printing. At this time, the thickness of the adhesive 2b to be applied is larger than the height of the conductor pattern 4, and printing is performed so that a gap is formed between the conductor pattern 4 and the adhesive 2b.
[0031]
Next, as shown in FIG. 3 (f), on the adhesive 2b formed on the printed wiring board 3, for example, a holding plate 10 on which an adhesive 2b represented by a Teflon substrate (Teflon is a registered trademark) is difficult to adhere. The weight 11 is mounted thereon, and the surface of the adhesive 2b is flattened. At this time, as shown in FIG. 3I, the volume of the portion 12 protruding from the conductor pattern 4 of the adhesive 2b of the printed wiring board 3 is the gap 13 provided at the boundary between the conductor pattern 4 and the adhesive 2b. The height of the adhesive 2b is adjusted by the weight of the weight 11 so as to be substantially the same as the volume of the weight 11.
[0032]
Thereafter, as shown in FIGS. 3 (g) and (h), the metal plate 1 coated with the adhesive 2a and the printed wiring board 3 coated with the adhesive 2b are bonded together, and the weight 7 is adjusted to 0.5. A load of 1 kgf / cm ² is applied to the adhesive 2 and the adhesive is cured at room temperature to 175 ° C. for about 1 to 12 hours.
[0033]
As described above, according to the third embodiment, a slight amount of the adhesive 2 protruding due to the adhesive surface pressure between the metal plate 1 and the printed wiring board 3 is at the boundary between the conductor pattern 4 and the adhesive 2. Since it is possible to retreat into the provided gap, it is possible to prevent the adverse effects caused by the protrusions with higher accuracy.
[0034]
Embodiment 4 FIG.
FIG. 4 is a cross-sectional view showing a metal substrate manufacturing process according to Embodiment 4 of the present invention. Hereinafter, a method of attaching a metal plate and a printed wiring board with an adhesive will be described with reference to FIG.
[0035]
As shown in FIGS. 4C and 4D, a non-conductive adhesive 14 is applied to the portion 6 of the printed wiring board 3 excluding the conductor pattern 4 by screen printing. At this time, the thickness of the adhesive 14 to be applied is larger than the height of the conductor pattern 4, and printing is performed so that a gap is formed between the conductor pattern 4 and the adhesive 14.
[0036]
On the other hand, as shown in FIGS. 4A and 4B, the conductive adhesive 16 is applied to the entire surface of the metal plate 1 except for the portion facing the nonconductive adhesive 14 printed on the printed wiring board 3. Print.
[0037]
After that, as shown in FIGS. 2E and 2F, the metal plate 1 coated with the conductive adhesive 16 and the printed wiring board 3 coated with the non-conductive adhesive 14 are bonded together. The load by the weight 7 is applied to both adhesives and pasted.
[0038]
As described above, according to the fourth embodiment, heat dissipation and conductivity can be ensured by interposing the conductive adhesive 16 between the conductor pattern 4 of the printed wiring board 3 and the metal plate 1. Further, the adhesion can be improved by interposing the non-conductive adhesive 14, which is superior in adhesion as compared with the conductive adhesive 16, between the portion 6 excluding the conductor pattern 4 and the metal plate 1. Further, the use of the non-conductive adhesive 14 can reduce the adhesive cost.
[0039]
Embodiment 5. FIG.
FIG. 5 is a sectional view showing a metal substrate on which a metal plate and a printed wiring board are bonded together according to Embodiment 5 of the present invention.
[0040]
In the present embodiment, the high thermal conductive adhesive 17 is applied to the portion 6 of the printed wiring board 3 excluding the conductor pattern 4 by screen printing. At this time, the thickness of the adhesive 17 to be applied is larger than the height of the conductor pattern 4, and printing is performed so that a gap is formed between the conductor pattern 4 and the adhesive 17. On the other hand, the conductive adhesive 16 is printed on the entire surface of the metal plate 1 except for the portion facing the high thermal conductive adhesive 17 printed on the printed wiring board 3. Then, the metal plate 1 to which the conductive adhesive 16 is applied and the printed wiring board 3 to which the high thermal conductive adhesive 17 is applied are bonded together, and the load by the weight 7 is applied to both the adhesives to be bonded.
[0041]
As described above, according to the present embodiment, the high thermal conductive adhesive 17 is printed only on the portion 6 of the printed wiring board 3 excluding the conductor pattern 4 and the conductive adhesive 16 is printed on the metal plate 1 and bonded together. Therefore, compared with the case where it adhere | attaches only with the conductive adhesive 16, heat dissipation and adhesiveness improve.
[0042]
Embodiment 6 FIG.
FIG. 6 is a cross-sectional view showing a metal substrate on which a metal plate and a printed wiring board are bonded according to Embodiment 6 of the present invention.
[0043]
In the figure, a metal plate 1 and a printed wiring board 3 on which a conductive pattern 4 and a through hole 5 are formed are bonded together by an adhesive 2 printed on both sides. The printed wiring board 3 and the adhesive layer 2 have poor adhesion because the outermost surface is adhered to the conductive pattern 4 plated with Au or the like at the position of the through-hole 3. The concave portion 6 excluding the conductor pattern 4 is firmly bonded to the resin or the like. Then, the pitch between the through holes 5 arranged on the printed wiring board 3 is set to ¼ or less of the wavelength (λ) of the electromagnetic wave generated from the high frequency circuit wired on the inner and outer layers. Further, a portion 6 excluding the conductor pattern 4 as much as possible is provided between the through holes 5.
[0044]
According to the present embodiment, leakage of electromagnetic waves generated from the high frequency circuit can be shielded, and other circuits are not adversely affected. As a result, it is possible to provide a metal substrate that has excellent high-frequency characteristics and excellent adhesion between the printed wiring board and the metal plate.
[0045]
【The invention's effect】
As described above, according to the present invention, the following effects are achieved.
[0046]
According to the first aspect of the present invention, since the adhesion between the concave portion excluding the conductor pattern of the printed wiring board and the metal plate is surely made by the adhesive printed on the printed wiring board side, the metal plate and the printed wiring board. It is possible to minimize the adhesive film thickness with the conductor pattern. As a result, for example, it satisfies the heat dissipation and electrical conductivity required for high-frequency printed wiring boards, and the adhesive sticks out from the end face of the metal substrate and through the through holes provided in the conductor pattern of the printed wiring board. It is possible to prevent the sticking out. In addition, the conductor pattern of the printed wiring board is usually soldered to the parts, so the outermost surface is usually gold-plated and generally has poor adhesion to the adhesive. Since it is bonded, it is possible to ensure good adhesion as a whole.
[0047]
According to the invention of claim 2, the conductive pattern of the printed wiring board is gold-plated on the outermost surface for soldering parts, and is generally inferior in adhesion to the adhesive, but the coated resist and metal plate As a result, it is possible to ensure good adhesion as a whole. Further, since the bonding is performed without dividing the conductor pattern, a strong ground can be provided and the high frequency characteristics are excellent.
[0048]
According to invention of Claim 3, the protrusion amount of an adhesive agent can be controlled with higher precision.
[0049]
In the inventions of claim 4 and claim 5, the conductive pattern of the printed wiring board and the metal plate use a conductive adhesive for heat dissipation and grounding, but the surface other than the conductive pattern of the printed wiring board is grounded. There is no need, and a non-conductive adhesive may be used. In general, a non-conductive adhesive has a stronger adhesive strength than a conductive adhesive, and thus the bonding strength can be increased.
[0050]
According to the invention of claim 6 and claim 7, the conductive pattern of the printed wiring board and the metal plate use the conductive adhesive for heat dissipation and grounding, but the surface other than the conductive pattern of the printed wiring board is grounded. It is possible to use non-conductive adhesive, but if the mounted element generates a large amount of heat, use a highly thermally conductive adhesive to increase heat dissipation while ensuring adhesiveness. I can do it.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a metal substrate manufacturing process according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a metal substrate manufacturing process according to a second embodiment of the present invention.
FIG. 3 is a sectional view showing a metal substrate manufacturing process according to a third embodiment of the present invention.
FIG. 4 is a sectional view showing a metal substrate manufacturing process according to a fourth embodiment of the present invention.
FIG. 5 is a sectional view showing a metal substrate according to a fifth embodiment of the present invention.
FIG. 6 is a sectional view showing a metal substrate according to a sixth embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a conventional metal substrate.
[Explanation of symbols]
1 Metal plate, 2, 2a, 2b Adhesive, 3 Printed wiring board, 4 Conductor pattern, 5 Through hole, 6 Recess, 7 Weight, 8 Resist, 10 Restraining plate, 11 Weight, 14 Non-conductive adhesive, 16 Conductive Adhesive, 17 High thermal conductive adhesive.

Claims (7)

In the method of manufacturing a metal substrate, in which a metal plate and a printed wiring board disposed on one main surface or both main surfaces of the metal plate are integrated by an adhesive,
A method for producing a metal substrate, comprising: a printed wiring board having an adhesive printed in a recess excluding a conductor pattern; and a metal plate having an adhesive printed on the entire surface of one main surface or both main surfaces. In the method of manufacturing a metal substrate, in which a metal plate and a printed wiring board disposed on one main surface or both main surfaces of the metal plate are integrated by an adhesive,
Covering the surface except the conduction portion of the heat radiation portion and the metal plate conductor pattern formed on the printed wiring board with a resist, a conductive adhesive to a conductive portion of the heat radiation portion and the metal plate of the printed circuit board the print method for producing a metal substrate, characterized in that bonding the above conductive printed wiring board and the adhesive is printed in the entire surface metal was printed conductive adhesive plate.   The volume of the adhesive protruding from the conductor pattern is printed on the concave portion of the printed wiring board excluding the conductor pattern so that the height is higher than the conductor pattern and a gap is formed between the conductor pattern and the adhesive. The metal substrate manufacturing method according to claim 1, wherein the volume is the same as the volume of the gap. In a metal substrate in which a metal plate and a printed wiring board arranged on one main surface or both main surfaces of this metal plate are integrated with an adhesive,
A non-conductive adhesive is formed between the concave portion excluding the conductive pattern of the printed wiring board and the metal plate, and a conductive adhesive is formed between the conductive pattern of the printed wiring board and the metal plate. Metal substrate. In the method of manufacturing a metal substrate, in which a metal plate and a printed wiring board disposed on one main surface or both main surfaces of the metal plate are integrated by an adhesive,
A printed wiring board in which a non-conductive adhesive is printed in a recess excluding a conductor pattern of the printed wiring board, and a metal plate in which a conductive adhesive is printed on the entire surface excluding a portion facing the non-conductive adhesive; A method for producing a metal substrate, characterized in that: In a metal substrate in which a metal plate and a printed wiring board arranged on one main surface or both main surfaces of this metal plate are integrated with an adhesive,
A heat conductive adhesive is formed between the concave portion excluding the conductor pattern of the printed wiring board and the metal plate, and a conductive adhesive is formed between the conductor pattern of the printed wiring board and the metal plate. Metal substrate. In the method of manufacturing a metal substrate, in which a metal plate and a printed wiring board disposed on one main surface or both main surfaces of the metal plate are integrated by an adhesive,
A printed wiring board printed with a heat conductive adhesive in the recesses excluding the conductor pattern and a metal plate printed with a conductive adhesive on the entire surface excluding the portion facing the heat conductive adhesive A metal substrate manufacturing method characterized by the above.

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