JP5614575B2 - Multilayer circuit board manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer circuit board.

It has been proposed that a multilayer circuit board is obtained by laminating a plurality of resin films, each having a conductor pattern formed only on one side, on a heat sink via a sheet member made of a thermoplastic resin and then heat-pressing from both sides (for example, a patent) Reference 1).
In addition, a multilayer circuit board on which a semiconductor element with a heat sink is mounted via solder balls has been proposed (see, for example, Patent Document 2).

JP 2003-17859 A JP 2001-244379 A

In a single-sided multilayer circuit board, when the heat of the electronic components mounted on the surface of the multilayer circuit board is released from the back side of the multilayer circuit board to the heat sink, the heat radiation path becomes longer and the heat radiation performance is reduced. .
When the resin of the resin layer interposed between the two in order to adhere the multilayer circuit board body to the heat sink is, for example, a thermosetting resin, the resin before being sufficiently cured is affected by the pressure in the heating press process. Therefore, the thickness of the resin layer is reduced. For this reason, it exists in the tendency for the thickness of the contact bonding layer after thermosetting to become thin.

In addition, since the lowermost layer of the multilayer circuit board body has irregularities in the portions with and without the conductor pattern, the resin layer before being sufficiently cured is strongly pressed particularly at the edge portion of the conductor pattern. The In the portion where the pressure is strongly applied, the thickness of the resin layer becomes very thin, and in some cases, the conductive pattern comes into contact with the heat sink, causing a short circuit failure.
The present invention has been made under such a background, and an object of the present invention is to provide a method for manufacturing a multilayer circuit board that has good heat dissipation and does not cause a short circuit failure.

In order to achieve the above object, the present invention provides a substrate body (2) in which a plurality of conductor layers (11, 12, 13, 14) are laminated via insulating layers (21, 22, 23), and a heat sink. (3) are bonded via the insulating first and second adhesive layers (4, 5), and the lowermost conductor layer (14) of the plurality of conductor layers is a peripheral edge of the substrate body. Of the multilayer circuit board ( 1) , including a conductor pattern (141 to 145) having an end surface spaced from the heat sink, an opposing surface facing the heat sink, and an edge portion formed by the opposing surface and the end surface A manufacturing method comprising: curing a first resin (40) to form a first adhesive layer bonded to one of the substrate body and the heat sink; and the substrate body and the heat sink while pressing the stacking direction (X1) and the conductor pattern of the lowermost conductive layer In a state where the first adhesive layer is interposed cured second resin (50) which is interposed between the substrate present body and the first adhesive layer between the serial facing surface and the heat radiating plate Forming a second adhesive layer.

According to the present invention, in the step of forming the second adhesive layer, even if the already cured first adhesive layer is pressed between the substrate body and the heat sink, the required thickness (t 4 ) Can be secured. Accordingly, in the step of forming the second adhesive layer, the thickness of the second adhesive layer is affected by the pressurization, specifically, the influence of being particularly strongly pressed at the edge portion of the lowermost conductor pattern. Thus, even when the thickness is partially reduced, a distance greater than the required thickness of the first adhesive layer can be ensured between the substrate body and the heat sink. Therefore, in the manufactured multilayer circuit board, the conductor pattern and the heat sink can be reliably insulated. Thus, since the reliability of ensuring insulation is high, the thickness of both adhesive layers can be made sufficiently thin as much as possible, and as a result, the heat dissipation to the heat sink can be enhanced.

The first adhesive layer and the second adhesive layer may be formed by thermosetting the first resin (40) and the second resin (50) (claim 2). In this case, in the step of forming the first adhesive layer, it is not necessary to apply a thermal load to the substrate body, so that there is no possibility of adversely affecting the resin constituting the insulating layer of the substrate body.
The present invention also includes a substrate body (2) formed by laminating a plurality of conductor layers (11, 12, 13, 14) via insulating layers (21, 22, 23), and a heat sink (3). Are joined via insulating first and second adhesive layers (4A, 5A), and the lowermost conductor layer (14) of the plurality of conductor layers has an end face separated from the peripheral edge of the substrate body. A method for producing a multilayer circuit board (1), comprising a conductor pattern (141 to 145) having a facing surface facing the heat radiating plate and an edge formed by the facing surface and the end surface. And curing the first resin to form a first adhesive layer bonded to the substrate body so as to cover the lower surface of the lowermost insulating layer, the end surface of the conductor pattern, and the opposing surface. And the heat sink while pressurizing the substrate body and the heat sink in the stacking direction. Forming a second adhesive layer by curing the second resin is interposed between the serial first adhesive layer, it is intended to include (claim 3).
According to the present invention, in the step of forming the second adhesive layer, even if the already cured first adhesive layer is pressed between the substrate body and the heat sink, the required thickness (t4A) Can be secured. Accordingly, in the step of forming the second adhesive layer, the thickness of the second adhesive layer is affected by the pressurization, specifically, the influence of being particularly strongly pressed at the edge portion of the lowermost conductor pattern. Thus, even when the thickness is partially reduced, a distance greater than the required thickness of the first adhesive layer can be ensured between the substrate body and the heat sink. Therefore, in the manufactured multilayer circuit board, the conductor pattern and the heat sink can be reliably insulated. Thus, since the reliability of ensuring insulation is high, the thickness of both adhesive layers can be made sufficiently thin as much as possible, and as a result, the heat dissipation to the heat sink can be enhanced.
The maximum value (tsummax) of the total thickness of the first adhesive layer and the second adhesive layer may be thinner than the thickness (t1, t2, t3) of each insulating layer of the substrate body. (Claim 4 ). As described above, a distance equal to or greater than the required thickness (t4; t4A) of the first adhesive layer can be ensured between the substrate body and the heat sink. Therefore, it is possible to make the maximum value of the total thickness of the first adhesive layer and the second adhesive layer substantially smaller than the thickness of each insulating layer of the substrate body. It is possible to arrange them close enough to each other, and the heat dissipation can be further improved.

The first resin and the second resin may be made of different materials, but when the first resin and the second resin are made of the same material (Claim 5 ), Since familiarity is good, it is preferable because the adhesive force between the first adhesive layer and the second adhesive layer can be increased.
As at least one of the first resin and the second resin, a known epoxy resin can be used as an adhesive. In addition, ceramic may be contained in at least one of the first resin and the second resin in order to increase thermal conductivity. In addition, at least one of a metal and carbon may be contained in at least one of the first and second resins in order to increase the thermal conductivity within a range where the insulation resistance is not lowered.

  In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a schematic sectional drawing of the multilayer circuit board manufactured by the manufacturing method of the multilayer circuit board which concerns on one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view sequentially showing manufacturing steps of the multilayer circuit board of the embodiment of FIG. 1. It is a schematic sectional drawing which shows the manufacturing process of the multilayer circuit board based on another embodiment of this invention in order.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a cross-sectional view of a multilayer circuit board manufactured by the method for manufacturing a multilayer circuit board of the present invention. As shown in FIG. 1, the multilayer circuit board 1 includes a board body 2 and a heat radiating plate 3 made of, for example, an aluminum plate. The substrate body 2 and the heat sink 3 are connected via a first adhesive layer 4 and a second adhesive layer 5 as two insulating adhesive layers.

The substrate body 2 is formed by laminating a plurality of conductor layers 11 to 14 via insulating layers 21 to 23. That is, the substrate body 2 includes the first conductor layer 11, the first insulating layer 21, the second conductor layer 12, the second insulating layer 22, the third conductor layer 13, and the third insulating layer as surface layers. The layer 23 and the fourth conductor layer 14 are formed by being laminated in this order.
Electronic components (not shown) are mounted on the conductor patterns 111 and 112 of the first conductor layer 11 as the surface layer. A plurality of conductor patterns 141 to 145 are formed on the fourth conductor layer 14 which is the lowermost conductor layer of the substrate body 2. The conductor pattern 111 of the first conductor layer 11 is connected to the conductor patterns 141 and 142 of the fourth conductor layer 14 through via holes 61 and 62. In addition, the conductor pattern 112 of the first conductor layer 11 is connected to the conductor patterns 143 and 144 of the fourth conductor layer 14 through via holes 63 and 64. Heat is released from the first conductor layer 11 as the surface layer on which the heat generating electronic component is mounted to the fourth conductor layer 14 at the lowest layer of the substrate body 2 through the via holes 61 to 64, and consequently The heat is dissipated to the heat radiating plate 3 side.

The maximum value tsummax of the total thickness of the first adhesive layer 4 and the second adhesive layer 5 is made thinner than the thicknesses t1, t2, t3 of the insulating layers 21-23. That is, the relationships of tsummax <t1, tsummax <t2, and tsummax <t3 are satisfied. Thereby, the distance between the board | substrate body 2 and the heat sink 3 is shortened, and the heat dissipation to the heat sink 3 side is improved.
Next, a method for manufacturing the multilayer circuit board 1 will be described with reference to FIG. First, as shown in FIG. 2A, a first resin 40 as a thermosetting resin in a state before curing (that is, an uncured or semi-cured state) is applied to the surface 3a of the heat radiating plate 3, for example. Apply in layers. In the case of a so-called prepreg in which the fiber bundle is impregnated with the uncured first resin 40, the prepreg is attached to the heat sink 3.

  For example, the first resin 40 applied to the heat radiating plate 3 is heated under reduced pressure (for example, in a vacuum state) to thermally cure the first resin 40. As a result, as shown in FIG. First adhesive layer 4 joined to 3 is formed. The reason why the pressure is reduced is to remove bubbles in the first resin 40. Thereby, it is possible to prevent unnecessary voids from remaining in the first adhesive layer 4 after being cured, and thus it is possible to prevent the occurrence of insulation failure.

Next, as shown in FIG. 2 (c), the first cured adhesive layer 4 has a surface as a thermosetting resin in a state before curing (that is, in an uncured or semi-cured state). For example, the second resin 50 is applied. In the case of a so-called prepreg in which the fiber bundle is impregnated with the uncured first resin 50, the prepreg is attached to the first adhesive layer 4.
Next, as shown in FIG. 2D, the substrate main body 2 as a sub-assembly formed in advance is placed on the second resin 50 applied, for example, on the surface of the first adhesive layer 4, and vacuum is applied. State. Then, the substrate main body 2 and the heat radiating plate 3 with the first adhesive layer 4 and the second resin 50 before curing interposed therebetween are heated while being pressed in the stacking direction X1 from above and below. As a result, the second resin 50 is thermally cured to form the second adhesive layer 5 in which the fourth conductor layer 14 and the first adhesive layer 4 are joined as shown in FIG. At the same time, the multilayer circuit board 1 is formed.

  As at least one of the first resin 40 and the second resin 50, a known epoxy resin can be used as an adhesive. In addition, ceramic may be contained in at least one of the first resin 40 and the second resin 50 in order to increase thermal conductivity. In addition, at least one of the metal and carbon may be contained in at least one of the first resin 40 and the second resin 50 in order to increase the thermal conductivity within a range where the insulation resistance is not lowered.

According to the present embodiment, the following operational effects are obtained. That is, in the hot press process for forming the second adhesive layer 5 shown in FIG. 2D, the already cured first adhesive layer 4 is pressed between the substrate body 2 and the heat sink 3. Even if it is done, a required thickness can be ensured.
Accordingly, in the step of forming the second adhesive layer 5, the thickness of the second adhesive layer 5 is, for example, the conductor patterns 141 to 145 of the fourth conductor layer 14 that is the lowermost layer of the substrate body 2 due to the influence of pressure. The thickness t4 of the first adhesive layer 4 that has already hardened between the substrate body 2 and the heat radiating plate 3 even if it becomes partially thin due to the influence of the edge portion of FIG. See e)] The above distance can be secured. Therefore, in the manufactured multilayer circuit board, the conductor patterns 141-144 and the heat sink 3 can be reliably insulated. Since the reliability of ensuring insulation can be increased in this way, the thickness of both adhesive layers 4 and 5 can be made sufficiently thin as much as possible. As a result, heat dissipation to the heat sink 3 can be achieved. Sexuality can be increased.

  In addition, referring to FIG. 1, a distance equal to or greater than the thickness t4 of the first adhesive layer 4 can be secured between the substrate body 2 and the heat radiating plate 3, so that the first adhesive layer 4 and the second adhesive layer 4 can be secured. It is possible to make the maximum value tsummax of the total thickness of the adhesive layers 5 substantially smaller than the thicknesses t1, t2, and t3 of the insulating layers 21 to 23 of the substrate body 2, and as a result, the substrate body 2 is dissipated. It can arrange | position close enough to the board 3, and can improve heat dissipation more.

Further, the first resin 40 constituting the first adhesive layer 4 to be bonded to the heat sink 3 out of the first adhesive layer 4 and the second adhesive layer 5 is cured first, In the step of forming the first adhesive layer 4, it is not necessary to apply a thermal load to the substrate body 2. Therefore, there is no possibility that the resin constituting each of the insulating layers 21 to 23 of the substrate body 2 will be adversely affected.
Note that the first resin 40 and the second resin 50 for forming the first adhesive layer 4 and the second adhesive layer 5 may be made of different materials, but are made of the same material. Is preferred. That is, in the case where they are made of the same material, the compatibility of both resins 40 and 50 is good, which is preferable in that the adhesive force between the first adhesive layer 4 and the second adhesive layer 5 can be increased.

In the present embodiment, the second resin 50 is applied to the first adhesive layer 4 as shown in FIG. 2C, but instead, the second resin is applied to the lower surface of the substrate body 2. 50 may be applied.
FIG. 3 shows a method for manufacturing a multilayer circuit board according to another embodiment of the present invention. In the manufacturing method, first, the first resin 40 is applied to the lower surface of the substrate body 2 as shown in FIG. Next, the applied first resin 40 is cured to form a first adhesive layer 4A bonded to the lowermost layer of the substrate body 2 as shown in FIG.

  Next, as shown in FIG. 3C, the second resin 50 is heated by pressing with the second resin 50 interposed between the first adhesive layer 4 </ b> A and the heat radiating plate 3. Harden. Thereby, as shown in FIG. 3D, the second adhesive layer 5A is formed, and the multilayer circuit board 1A is manufactured. As shown in FIG. 3 (c), as a step before the second resin 50 is interposed between the first adhesive layer 4A and the heat radiating plate 3, the second resin 50 is replaced with the first adhesive layer 4A or the heat radiating plate 3. What is necessary is just to apply | coat etc. to any one of these. In the components of the embodiment of FIG. 3, the same reference numerals as those of the embodiment of FIG. 2 are given to the same components as those of the embodiment of FIG.

According to the present embodiment, the following operational effects are obtained. That is, in the heat press step shown in FIG. 3C, the first cured adhesive layer 4A is secured to the required thickness even if it is pressed between the substrate body 2 and the heat radiating plate 3. be able to.
Therefore, in the next step of forming the second adhesive layer 5A, the thickness of the second adhesive layer 5A is, for example, the conductor pattern 141 of the fourth conductor layer 14 which is the lowermost layer of the substrate body 2 due to the influence of pressure. The thickness t4 of the first adhesive layer 4A that has already hardened between the substrate body 2 and the heat sink 3 even though it may be partially thin due to the influence of the edge portion of ~ 145 [FIG. 2 (e) can be ensured. Therefore, in the manufactured multilayer circuit board 1A, the conductor patterns 141 to 145 and the heat sink 3 can be reliably insulated. Since the reliability of ensuring insulation can be increased in this way, the thickness of both adhesive layers 4A and 5A can be made sufficiently thin as much as possible, and as a result, heat dissipation to the heat sink 3 can be achieved. Sexuality can be increased.

  Moreover, since the distance more than thickness t4A of 1st contact bonding layer 4A can be ensured between the board | substrate body 2 and the heat sink 3, total thickness of 4 A of 1st contact bonding layers and 5 A of 2nd contact bonding layers. Can be made substantially thinner than the thicknesses t1, t2 and t3 of the insulating layers 21 to 23 of the substrate body 2, and as a result, the substrate body 2 can be made sufficiently close to the radiator plate 3. It can arrange | position and can improve heat dissipation more.

  Note that the first resin 40 and the second resin 50 for forming the first adhesive layer 4A and the second adhesive layer 5A may be made of different materials, but are made of the same material. Is preferred. That is, in the case where they are made of the same material, the familiarity between the two resins 40 and 50 is good, which is preferable in that the adhesive force between the first adhesive layer 4A and the second adhesive layer 5A can be increased. The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims.

  DESCRIPTION OF SYMBOLS 1; 1A ... Multilayer circuit board, 2 ... Board | substrate body, 3 ... Heat sink, 4; 4A ... 1st contact bonding layer, 5; 5A ... 2nd contact bonding layer, 11 ... 1st conductor layer, 111, 112 ... Conductor pattern, 12 ... 2nd conductor layer, 13 ... 3rd conductor layer, 14 ... 4th conductor layer, 141-145 ... conductor pattern, 21 ... 1st insulating layer, 22 ... 2nd insulating layer, 23 ... 3rd insulating layer, 40 ... 1st resin, 50 ... 2nd resin, X1 ... Lamination direction, t1, t2, t3 ... (Each insulating layer) thickness, t4; t4A ... (1st adhesion | attachment) Thickness of layer, tsummax; tAsummax ... maximum value of total thickness (of first adhesive layer and second adhesive layer)

Claims (5)

A substrate body formed by laminating a plurality of conductor layers via an insulating layer, and a heat sink are joined via insulating first and second adhesive layers ,
The lowermost conductor layer of the plurality of conductor layers is an end surface spaced from the peripheral edge of the substrate body, an opposing surface facing the heat sink, an edge portion formed by the opposing surface and the end surface, A method for producing a multilayer circuit board, comprising a conductor pattern having
Forming a first adhesive layer bonded to the heat plate release by curing the first resin,
While pressing the substrate body and the heat sink in the laminating direction, the substrate book in a state where the first adhesive layer is interposed between the facing surface of the conductor pattern of the lowermost conductor layer and the heat sink. Forming a second adhesive layer by curing a second resin interposed between the body and the first adhesive layer. Oite to claim 1, said first adhesive layer and the second adhesive layer, the first resin and second resin a method of manufacturing a multi-layer circuit board that is formed by thermally curing. A substrate body formed by laminating a plurality of conductor layers via an insulating layer, and a heat sink are joined via insulating first and second adhesive layers,
The lowermost conductor layer formed on the lower surface of the lowermost insulating layer includes an end surface spaced from the peripheral edge of the substrate body, an opposing surface facing the heat sink, and an edge portion formed by the opposing surface and the end surface A multilayer circuit board comprising a conductor pattern having
A manufacturing method of
Curing a first resin to form a first adhesive layer bonded to the substrate body so as to cover the lower surface of the lowermost insulating layer and the end surface and the opposing surface of the conductor pattern; ,
Curing the second resin interposed between the heat sink and the first adhesive layer while pressurizing the substrate body and the heat sink in the stacking direction to form a second adhesive layer; A method for manufacturing a multilayer circuit board comprising: 4. The multilayer circuit according to claim 1, wherein the maximum value of the total thickness of the first adhesive layer and the second adhesive layer is thinner than the thickness of each insulating layer of the substrate body. A method for manufacturing a substrate. In any one of claims 1 to 4, the first resin and the second resin is a method for manufacturing a multilayer circuit board made of the same material.

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