JP2732149B2 - Substrate for mounting electronic components - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic component mounting board for mounting an electronic component, and particularly to a measure for sealing the resin.

[Conventional technology]

As shown in FIG. 5, the electronic component mounting board 9 includes an insulating base 91 having a mounting recess 95 for mounting a heat sink, and a heat sink 8 bonded to the mounting recess 95 via an adhesive 85. And a concave electronic component mounting portion 70 provided on the back surface 81 of the heat sink 8.

The heat sink 8 is provided in the electronic component mounting section 70.
The electronic component 7 is bonded to the back surface 81 of the device via an adhesive 85. Also, around the electronic component 7 mounted in this way,
In order to prevent moisture from entering the electronic component 7, a moisture-resistant resin
Resin sealing by 60 is performed. As shown in the figure, the resin sealing is performed by filling the moisture-resistant resin 60 into a dam frame 75 provided on the back surface of the insulating base material 91 on the outer periphery below the electronic component mounting portion 7. Done.

In the figure, reference numeral 92 denotes a through hole, 93 denotes a conductor pin, 76 denotes a metal cover, and 71 denotes a bonding wire.

In the above resin sealing, the electronic component mounting section 7 is used.
6, the heat-softened moisture-resistant resin 60 is dropped into the dam frame 75 and cooled and solidified. It is done by.

[Problem to be solved]

However, in the conventional electronic component mounting board 9, since the resin sealing is performed in a drop-in manner as described above, a large number of bubbles are mixed in the moisture-resistant resin 60 that has been cooled and solidified.

If a large number of air bubbles are mixed in the moisture-resistant resin 60 sealed with the resin, moisture easily enters the electronic component 7 through the air bubble portion.

In addition, the moisture that has entered through the air bubbles causes the insulating substrate 91
And the heat sink 8 and the adhesive 85 between the insulating base material 91 and the electronic component 7. Then, the adhesive 85 swells due to the moisture,
Adhesive strength decreases.

In the worst case, the heat sink 8 may fall off the insulating base material 91.

It is an object of the present invention to provide an electronic component mounting board which does not generate air bubbles in a wet resin and does not cause a heat sink to fall off.

[Solutions to solve the problem]

The present invention provides a heat sink, an insulating base having a mounting recess for mounting the heat sink larger than the outer periphery of the heat sink, a heat sink bonded to the mounting recess through an adhesive, and the heat sink. In the electronic component mounting board comprising the electronic component mounting portion provided on the back side of the electronic component mounting portion, the groove formed between the heat sink and the mounting recess penetrates through the insulating base material. The groove has a plurality of sealing resin flow holes communicating therewith, and the groove has a protrusion for positioning a heat sink protruding from a side wall of the mounting recess, and the protrusion is located between the surface of the insulating base material. The electronic component mounting board is also characterized in that a deaeration groove is formed by being positioned inside.

The most remarkable point in the present invention is that the sealing resin circulation hole is provided in the groove formed between the heat sink and the mounting recess, and the protrusion for positioning the heat sink is provided. This is due to the provision of a deaeration groove.

The sealing resin flow hole is a hole for communicating between the mounting recess for mounting the heat sink and the electronic component mounting portion side, and a passage for smoothly filling the moisture-resistant resin therebetween during resin sealing. It is. The diameter of the sealing resin flow hole is preferably 0.5 to 2.0 mm. If it is less than 0.5 mm, the moisture-resistant resin is difficult to flow at the time of resin sealing, and if it exceeds 2.0 mm, the space between the heat sink and the mounting recess becomes large, and the space for forming the conductor circuit provided on the insulating base material is reduced.

Further, it is preferable that at least one sealing resin circulation hole is provided on each side of the heat radiating plate. One is a hole through which the moisture-resistant resin flows into the electronic component mounting portion, and the other is a hole through which the moisture-resistant resin flows out of the electronic component mounting portion into the groove.

The projecting portion is provided for smoothly disposing the heat radiating plate when the heat radiating plate is mounted in the mounting recess, and is provided so as to protrude into the groove. It is preferable that the protrusions are provided at a plurality of positions. In addition, the upper surface of the protruding portion is located inside the surface of the insulating base material to form a deaeration hole. This is because, as described later, when the moisture-resistant resin injected at the time of resin sealing flows out from the electronic component mounting portion side to the groove side, air is smoothly released.

In addition, as the moisture resistant resin, thermoplastic epoxy resin,
A molding resin or the like is used.

Next, in performing the resin sealing on the electronic component mounting board, first, a heat radiating plate is bonded to the mounting recess of the insulating base material via an adhesive. At this time, the radiator plate is positioned and joined by the protrusion. Further, the electronic component is bonded to the electronic component mounting portion via an adhesive. Next, wire bonding is performed between the conductor circuit provided on the insulating base material and the electronic component. Thereafter, the electronic component mounting substrate is placed in a resin sealing mold. The mold is
It has a cavity that covers the periphery of the electronic component and the groove (see FIG. 4).

Therefore, the heat-softened moisture-resistant resin flows from the joint side of the heat radiating plate, that is, the groove side to the electronic component mounting portion side through the sealing resin circulation hole. After filling the electronic component mounting portion, the moisture-resistant resin overflows again into the groove from one of the sealing resin flow holes to fill the groove. Then, it slightly flows out of the mold. At this time, the air in the cavity and the groove, which is pushed out by the moisture-resistant resin, collects in the deaeration groove on the protruding portion and is further discharged out of the mold.

Thereafter, the moisture-resistant resin is cooled and solidified, and the electronic component mounting substrate is removed from the mold. As a result, an electronic component mounting substrate is obtained in which not only the electronic component mounting portion but also the groove between the heat sink and the mounting recess is filled with the moisture-resistant resin.

[Action and effect]

In the electronic component mounting board of the present invention, a sealing resin circulation hole is provided between the groove and the electronic component mounting portion side.
Therefore, when sealing the resin, the electronic component mounting board is placed in the mold as described above, the electronic component mounting portion is filled with the moisture-resistant resin through the sealing resin flow hole from the groove side, and one of the sealing is performed. The moisture-resistant resin overflows to the groove side through the resin flow holes, so that the inside of the groove can be filled.

Since the filling of the moisture-resistant resin is performed by press-fitting such as injection molding, a large number of air bubbles are not generated in the moisture-resistant resin as in a conventional drop-in method. Therefore,
The filled moisture-resistant resin has a high density and does not allow moisture to enter electronic components and adhesives.

In addition, since the moisture-resistant resin is also filled in the groove between the heat sink and the mounting recess, moisture does not enter the adhesive between the heat sink and the insulating base. In addition, there is no possibility that the heat sink will fall off.

Also, since the protruding portion is provided in the groove,
The heat sink can be easily positioned in the mounting recess. Therefore, the end of the radiator plate does not close the sealing resin circulation hole due to the displacement of the radiator plate.

As described above, according to the present invention, there is no generation of air bubbles in the moisture-resistant resin at the time of resin sealing, and there is no risk of the heat sink being dropped off, and furthermore, the electronic component mounting that can accurately position the heat sink. Substrate can be provided.

〔Example〕

An electronic component mounting board according to an embodiment of the present invention will be described.
This will be described with reference to FIGS.

As shown in FIGS. 1 to 3, the electronic component mounting board of this embodiment has a mounting recess 11 for mounting a heat sink, which is larger than the outer periphery of the heat sink 8, and a mounting recess 11, The heat radiating plate 8 is bonded to the heat radiating plate 8 via an adhesive 85, and has a concave electronic component mounting portion 70 provided on the back side of the heat radiating plate 8.

In the groove 15 formed between the heat sink 8 and the mounting recess 11, the electronic component mounting part 70
It has a plurality of sealing resin circulation holes 12 communicating with the side. Also,
The groove 15 has a protrusion 17 for positioning the heat sink protruding from the side wall of the mounting recess 11 (FIGS. 2 and 3). The projecting portion 17 is located inside the surface of the insulating substrate 1 to form a deaeration groove 171 (FIG. 3). The insulating base 1 has a through hole 13 for inserting the conductor pin 93.

In the groove 15, as shown on the left side of FIG. 2, weirs 18 are provided on the left and right of the sealing resin flow hole 12 for injecting the moisture-resistant resin. .
The weirs 18, 18 are formed up to the upper surface of the insulating base material 1, unlike the protrusions 17.

The mounting recess 11 is formed by counterboring an insulating base material, and the sealing resin flow hole 12 is formed by drilling. The sealing resin flow holes 12 have a hole diameter of 1.0 mm, and as shown in FIG. 2, a total of eight holes are formed at the four corners of the groove 11 and between them. Also, the protrusions 17 are provided one by one on three pieces of the square groove 15. The width of the groove 15 is
1.0mm, depth is 1.0mm.

Further, the heat radiating plate 8 is made of a copper plate.
A notch 82 is provided at a position opposing to. The notch 82 prevents the space of the conductor circuit provided on the insulating base material 1 from being reduced by the formation of the sealing resin flow hole 12, which increases the width of the groove 15.

Also, after the electronic component mounting section 70 has joined the heat sink 8,
The insulating base material 1 and the adhesive 85 are formed by counterbore processing to the back surface side 81 side of the heat sink 8.

Next, the case where the electronic component mounting substrate is sealed with resin will be described with reference to FIG.

First, prior to resin sealing, the electronic component 7 is bonded to the back surface 81 of the heat sink 8 with the adhesive 85 in the concave electronic component mounting portion 70 of the insulating base material 1. Then, a bonding wire 71 is connected between the electronic component 7 and the conductor circuit.
Further, the conductor pins 93 are inserted into the through holes 13 of the insulating base material 1. Thus, an electronic component mounting board 10 on which the electronic components 7 are mounted is configured.

Next, as shown in the figure, the electronic component mounting substrate is placed in a resin sealing mold 20. The mold 20 is an upper mold 2
And the lower mold 3. The upper die 2 is a substrate 10 for mounting electronic components.
It has a concave portion 24 in contact with the upper surface, an inlet 21 for injecting the moisture-resistant resin, and an outlet 22 for letting out excess moisture-resistant resin.

On the other hand, the lower mold 3 has a recess 31 covering the lower part of the electronic component 7 and the sealing resin flow hole 12 and a space portion for accommodating a large number of conductor pins 93.
Has 35. The upper opening edge 310 of the recess 31 is configured to be in close contact with the back surface of the insulating base material 1. In addition, the injection port 21 of the upper die 2 is provided with the sealing resin flow hole 12 (left side in FIG. 2) of the eight sealing resin flow holes 12 for injecting the moisture-resistant resin into the electronic component mounting portion 70 side. Only communicates with On the other hand, the outlet 22 communicates with the other seven sealing resin circulation holes 12.

Then, as shown in FIG. 4, the electronic component mounting substrate 10 is sandwiched between the lower die 3 and the upper die 2, and
The moisture-resistant resin softened by heating from 21 is injected at a pressure of about 30 to 50 kg / cm ² .

The injected moisture-resistant resin is used as the sealing resin flow hole 12 at the injection port.
(The left side of FIG. 2). Then, the resin is injected into the cavity 30 formed between the insulating base material 1 and the recess 31 of the lower mold 3 through the sealing resin flow hole 12, and is filled in the cavity 30. That is, the periphery of the electronic component 7 is sealed with the moisture-resistant resin. Further, at the time of the injection, since the weirs 18 are provided on both sides of the sealing resin flow hole 12 on the injection side, the moisture-resistant resin flows only into the electronic component mounting portion 70 side.

Further, the moisture resistant resin overflows into the groove 10 through the seven sealing resin flow holes 12 for outflow, and further excess moisture resistant resin overflows from the outlet 22 of the upper mold 2. At the time of injecting the moisture-resistant resin, the air in the cavity 30 enters the groove 15 above the sealing resin flow hole 12, further passes through the deaeration groove 171 above the protrusion 17, and It is discharged from the outlet 22.

Therefore, the injection of the moisture-resistant resin is stopped, the solidified resin is cooled and solidified, and the electronic component mounting substrate 1 is taken out of the mold 20, whereby the periphery of the electronic component 7, the groove 15 and the sealing resin flow hole 12 are removed. The electronic component mounting board 1 whose inside is resin-sealed with the moisture resistant resin is obtained.

As described above, according to the present embodiment, since the moisture-resistant resin is filled by pressure injection, high-density resin sealing is performed without generating air bubbles in the moisture-resistant resin as in the related art. be able to. Therefore, there is no penetration of moisture into the electronic component 7 and the adhesive 85 and no swelling of the adhesive 85.

In addition, since the moisture-resistant resin is also filled in the groove 15, moisture does not enter the adhesive 85 between the heat sink 8 and the insulating base 1, and the adhesive 85 does not deteriorate. . Therefore,
There is no risk of the heat sink 8 falling off.

Further, since the projecting portion 17 is provided in the mounting recess 11, the heat sink 8 can be easily positioned in the mounting recess 11, and the sealing resin circulation hole 12 is not closed.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 show an electronic component mounting board according to an embodiment of the present invention, FIG. 1 is a cross-sectional view thereof, FIG. FIG. 3 is a perspective view of a main portion of a groove and a portion where a sealing resin circulation hole is formed, FIG. 4 is a sectional view of a mold at the time of resin sealing, and FIG.
The figure is a sectional view of a conventional electronic component mounting substrate. DESCRIPTION OF SYMBOLS 1 ... Insulating base material, 10 ... Electronic component mounting board, 11 ... Mounting recess, 12 ... Sealing resin circulation hole, 15 ... Groove, 17 ... Protrusion, 18
... cough, 60 ... moisture resistant resin, 7 ... electronic parts, 70 ... electronic parts mounting part, 8 ... heat sink,

Claims (1)

(57) [Claims] 1. A heat sink, an insulating base having a mounting recess for mounting the heat sink larger than the outer periphery of the heat sink, a heat sink bonded to the mounting recess through an adhesive, and the heat sink. An electronic component mounting board comprising an electronic component mounting portion provided on the back surface side of the board, wherein the groove formed between the heat sink and the mounting recess penetrates through the insulating base material and the electronic component mounting portion. And a plurality of sealing resin flow holes communicating with the mounting side, and a projection for positioning a heat sink protruding from the side wall of the mounting recess in the groove, and the projection is provided on the surface of the insulating base material. A substrate for mounting an electronic component, wherein a deaeration groove is formed inside the substrate.