JP7147205B2 - Mounting substrate and mounting structure - Google Patents

Description

The present invention relates to a mounting board and a mounting structure.

2. Description of the Related Art Package parts, in which electronic parts such as semiconductor ICs (Integrated Circuits) are molded with resin, are widely used. Some of such package components have thermal pads with large areas on the mounting surface (bottom surface) in addition to electrical signal terminals. This thermal pad is soldered to the thermal land of the circuit board to form a mechanism for dissipating heat generated by the electronic component to the circuit board side.

In the soldering of the thermal pad and the thermal land, since the solder joint surface is large, the gas generated during heating may remain in the solder and generate voids. If there is a void, there is a problem that heat dissipation, bonding strength, reliability, etc. are lowered.

Therefore, a thermal land structure in which voids are less likely to occur has been proposed. For example, Patent Literature 1 discloses a technique of dividing a thermal land into a plurality of regions with a resist. According to this technique, since the region where the solder is continuous is reduced, the gas generated during heating can easily escape from the solder, and the generation of voids can be suppressed.

Japanese Patent Laid-Open No. 2002-200001 discloses a technique of forming slits in the conductive layer of the thermal land to expose the base material surface and dividing the area to which the solder is applied. According to this technique, as with the technique of Patent Document 1, the area where the solder is continuous is reduced, and the gas can easily escape. In addition, voids can be suppressed from occurring because a path for gas to escape is formed through the slits where there is no solder.

JP-A-2002-026468 JP 2006-147723 A

However, in the technique of Patent Document 1, each region is surrounded by a resist wall, and the top and bottom are blocked by a thermal pad and a thermal land, so the gas generated from each region is released to the outside. No route. As a result, the effect of suppressing voids was limited.

In addition, in the technique of Patent Document 2, when the solder flows during heating, the solder applied to adjacent regions may come into contact with each other beyond the slits and be integrated. In such a case, there is a problem that the volume of continuous solder becomes large, making it difficult for the gas to escape. In addition, there is also a problem that the solder of a plurality of regions is integrated and separated from each other, resulting in uneven heat dissipation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mounting substrate capable of efficiently suppressing the generation of voids in a heat radiating portion.

In order to solve the above problems, the mounting board has an insulating base material, a conductor film, and a partition wall. The conductor film consists of a material that bonds with solder and is laminated as a series of films on the substrate. A partition wall is formed on the conductor film to partition the conductor film into a plurality of compartments. The partition wall is made of a material that does not react with solder, and has a first wall portion with a first height from the upper surface of the conductor film and a second wall portion with a second height lower than the first height. is doing. When solder is supplied to each compartment and the thermal pad of the package component is joined above the partition wall, the solder in each compartment connects the thermal pad and the conductive film while being separated from each other. A gap is formed between adjacent solders, the bottom of which is defined by the second wall. Via this gap, the gas generated from the solder is released to the outside, and the formation of voids in the solder can be suppressed.

An advantage of the present invention is that it is possible to provide a mounting substrate that can efficiently suppress the generation of voids in the heat radiating portion.

1 is a plan view showing a mounting board according to a first embodiment; FIG. It is a top view which shows the mounting board|substrate of 2nd Embodiment. It is a sectional view showing a mounting substrate of a second embodiment. FIG. 10 is a plan view showing a package component used in the mounting structure of the second embodiment; It is a top view which shows the mounting structure of 2nd Embodiment. It is a sectional view showing a mounting structure in a second embodiment. FIG. 9 is a plan view showing an example of gas flow in the second embodiment; It is a top view which shows the mounting board|substrate of 3rd Embodiment. It is a sectional view showing a mounting substrate of a 3rd embodiment. It is a top view which shows the mounting board|substrate of 4th Embodiment. It is a top view which shows the mounting board|substrate of 5th Embodiment. It is a top view which shows the mounting board|substrate of 6th Embodiment. It is a sectional view showing a mounting substrate of a sixth embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiments described below are technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following. In addition, the same number may be attached|subjected to the same component of each drawing, and description may be abbreviate|omitted.

(First embodiment)
FIG. 1 is a plan view showing the mounting substrate of the first embodiment. FIG. The mounting substrate has a base material 1 , a conductor film 2 and partition walls 3 .

The base material 1 is made of an insulating material and has a flat plate shape.

The conductor film 2 is laminated as a series of films on the substrate 1 . The conductor film 2 is made of a material that has excellent solder wettability and reacts with solder.

The partition wall 3 is formed on the conductor film 2 and partitions the conductor film 2 into a plurality of compartments. The partition wall 3 consists of a first wall portion 3a having an upper surface at a first height from the upper surface of the conductor film 2 and a second wall portion 3b having an upper surface at a second height lower than the first height. have. The partition wall 3 is made of a material that does not react with solder and has poor solder wettability.

With the above configuration, each compartment partitioned by the partition wall 3 has a bottom surface formed of the conductor film 2 that can be joined with solder and a space surrounded by the partition wall 3 that does not react with the solder. And each partition wall 3 has the 2nd wall part 3b lower than the 1st wall part 3a.

In the above configuration, when solder is supplied to each compartment and the thermal pad of the package component is joined above the partition wall 3, the solder arranged in each compartment is separated from each other, and the thermal pad and the conductor film 2 are separated from each other. to connect. A gap whose bottom surface is defined by the second wall portion 3b is formed between the solder in one section and the solder in the adjacent section. If gas is generated when the solder is heated, the gas is released to the outside of the conductive film 2 through this gap. As a result, it is possible to suppress the formation of voids in the solder.

As described above, in the mounting substrate of the present embodiment, it is possible to efficiently suppress the generation of voids in the heat radiating portion.

(Second embodiment)
FIG. 2 is a plan view showing the mounting board 100 of the second embodiment. The mounting board 100 has a base material 110 , a thermal land 120 and a partition wall 130 . Also, a terminal land 140 is provided on the outer peripheral portion separated from the thermal land 120 .

3(a) is a cross-sectional view showing a cross section along AA' in FIG. 2, and FIG. 3(b) is a cross-sectional view showing a cross section along BB' in FIG.

The mounting board 100 is a flat board for mounting package components, and the base material 110 is made of an insulating material.

The thermal land 120 is a solderable conductor laminated as a series of films, a so-called solid film, laminated on the substrate 110 . By soldering the thermal pad of the package component to the thermal land 120, the heat generated in the package component can be dissipated to the mounting substrate 100 side.

The terminal land 140 is a conductor for connecting with the terminal of the package component. Terminal land 140 can be formed of the same conductor as thermal land 120, for example.

The partition wall 130 is a wall that is formed on the thermal land 120 and partitions the thermal land 120 into a plurality of sections. The partition wall 130 has a first wall portion 130a having a predetermined first height and a second wall portion 130b having a height lower than that of the first wall portion. In this example, the first walls are arranged at the intersections of the partition walls, and the second walls are arranged at the sides. The partition wall 130 is formed using a material that has poor solder wettability and does not react with solder. Solder resist, for example, can be used as the material of the partition wall.

As shown in FIGS. 3A and 3B, the partition wall 130 has a first wall portion 130a with a height g and a second wall portion 130b with a height h lower than g.

FIG. 4 is a plan view showing the package component 200 mounted on the mounting substrate 100. FIG. The package component 200 has a mold 210 that seals an electronic component (not shown), terminals 220 that connect to the electronic component, and thermal pads 230 . Terminals 220 are contacts for connecting electronic components and external circuits, and thermal pads 230 are for thermally connecting to an external heat sink or the like to dissipate heat generated by the electronic components.

FIG. 5 is a plan view showing a mounting structure in which the package component 200 is soldered to the mounting substrate 100. As shown in FIG. In this example, the thermal land 120 and the thermal pad 230 have the same outer shape. The connection between the two is partitioned into a plurality of (here, 12) compartments by partition walls 130 . The first wall portion 130a is arranged at the intersection of the partition walls 130, and the second wall portion 130b is arranged at the side portion dividing the adjacent partitions. Although not shown, each section is filled with solder to connect the thermal pad 230 and the thermal land 120 .

6A and 6B are cross-sectional views taken along lines CC' and DD' in FIG. Here, terminals 220 and terminal lands 140 are connected by solder 150, and thermal pads 230 and thermal lands 120 are connected by solder.

In the cross-section of FIG. 6(a), it is the first wall 130a that separates the solder 150 arranged in adjacent compartments. Since the partition wall 130 repels the solder 150, the cross section of the solder 150 spreads to the edge of the partition wall 130 at the junction with the thermal pad 230 and the thermal land 120, and the gap between the partition wall 130 at the intermediate portion. is made.

In the cross section of FIG. 6(b), adjacent sections of solder 150 are separated by the second wall 130b. Since the upper surface of the second wall portion 130b is lower than the upper surface of the first wall portion 130a, a gap 160 is formed between the thermal pad 230 and the second wall portion 130b.

FIG. 7 is a schematic plan view of the gas flow G in the connection structure 300 described above. The solder 150 shown in FIG. 7 is drawn as a cross-section of the central portion in the thickness direction. As described with reference to FIG. 6( a ), a gap is formed between the solder 150 and the partition wall 130 due to the effect of the partition wall 130 repelling the solder 150 at the central portion in the thickness direction. A gap 160 whose bottom surface is the top surface of the second wall portion 130b exists between the solders 150 in adjacent sections. The gas generated by the solder 150, hatched in FIG. 7, is released outside the connection structure 300 through these gaps. This reduces the probability that gas will be trapped in the solder 150 and form voids.

(Example 1)
A mounting board of the second embodiment was produced by the following method.

First, a thermal land was formed with a Cu film on a glass epoxy substrate.

Next, a solder resist was applied to a thickness of 100 μm, and a second wall pattern was formed by photolithography. The width of the second wall was 0.2 mm. The size of each section was 1.4 mm×1.2 mm.

Next, a solder resist was applied to a thickness of 50 μm, and a first wall was formed by photolithography so as to form a cross with a length of 0.6 mm at the intersection of the second walls.

As described above, according to this embodiment, the gas generated from the solder can be released to the outside, thereby suppressing the generation of voids.

(Third embodiment)
In the second embodiment, the outer peripheral portion of the thermal land 120 and the thermal pad 230 is open, but an outer peripheral wall having the same structure as the partition wall may be provided on the outer peripheral portion. FIG. 8 is a plan view showing a mounting board 101 having such a structure.

The mounting substrate 101 has an outer peripheral wall 131 in addition to the configuration of the second embodiment. The outer peripheral wall 131 is provided on the outer periphery of the thermal land 120 and includes a third wall portion 131 having the same height as the first wall portion 130a and a fourth wall portion 131b lower than the third wall portion 131a. have. The height of the fourth wall portion 131b can be, for example, the same as that of the second wall portion 130b, but may be different. The presence of the outer peripheral wall 31 can prevent the solder 150 from flowing out of the thermal land 120 .

When the package component 200 is mounted on this mounting substrate 101, a gap corresponding to the fourth wall is formed in the outer peripheral portion. Gas can be released to the outside through this gap. In FIG. 8, the gas generated by the solder 150 that is virtually placed is schematically depicted as a gas flow G that is discharged through the gap.

9A and 9B are cross-sectional views taken along lines EE' and FF' of FIG. 8, respectively. As shown in FIG. 9(a), the cross section of EE' is the third wall portion 131a having a height of g, and the cross section of FF' is the fourth wall portion having a height of h. 131b. Therefore, when a package component is mounted from above, a gap having a height of (gh) is formed in the cross section of FF'.

As described above, according to the present embodiment, it is possible to suppress the occurrence of voids by providing a wall for preventing the solder from flowing out from the outer peripheral portion while securing a gas escape path.

(Fourth embodiment)
In the first to third embodiments, the second walls are provided between all the adjacent sections to secure the gaps, but the gaps do not necessarily have to be present between all the sections. For example, as shown in FIG. 10, a second wall portion may be provided between adjacent sections in the vertical direction of the drawing, and may not be provided on the left and right sides of the drawing.

In such a configuration, the second wall portion 130b and the fourth wall portion 131b may be arranged continuously from each section to the outside. As a matter of course, the layout of the second wall portion and the fourth wall portion is not limited to the example of FIG. 10, and any layout that satisfies the above conditions can be used.

(Fifth embodiment)
In the first to fourth embodiments, the section of the thermal land surrounded by the partition wall is rectangular, but may be of any shape other than rectangular. For example, the partitions may be circular like the mounting substrate 102 shown in FIG. 11, or may be elliptical or other shapes. In this case also, as in the first to fourth embodiments, the thermal pad is supported by the first wall portion 130a, and each compartment is provided with a second wall portion 130b between at least one adjacent compartment. , the gap should be continuous to the outside.

(Sixth embodiment)
FIG. 12 is a plan view showing the mounting board 103 of the sixth embodiment. The mounting substrate 103 of this embodiment has a through hole 170 penetrating from the upper surface of the second wall portion 130b to the back surface of the base material 110 in the second wall portion 130b.

13 is a cross-sectional view taken along line II' of FIG. 12. FIG. As shown in FIG. 13 , the through hole 170 penetrates from the upper surface of the second wall portion 130 b to the rear surface of the base material 110 . Gas generated in the solder can escape to the outside through the through-holes 170, so that the gas can be released efficiently. As a result, the generation of voids can be suppressed.

The present invention has been described above using the above-described embodiments as exemplary examples. However, the invention is not limited to the above embodiments. That is, within the scope of the present invention, various aspects that can be understood by those skilled in the art can be applied to the present invention.

Reference Signs List 1, 110 base material 2 conductor film 3, 130 partition wall 100, 101, 102, 103 mounting substrate 120 thermal land 130a first wall portion 130b second wall portion 131 outer peripheral wall 140 terminal land 150 solder 160 gap 170 through hole 200 package component 210 mold 220 terminal 230 thermal pad

Claims (10)

an insulating substrate;
a conductor film laminated on the substrate;
an insulating partition wall provided on the conductor film and partitioning the conductor film into a plurality of compartments;
The partition wall is
a first wall portion disposed at the intersection of the partition walls and having an upper surface at a first height from the upper surface of the conductor film;
and a second wall portion disposed on a side portion of the partition wall that partitions the adjacent partitions and having an upper surface at a second height that is lower than the first height.
each of said compartments,
2. The mounting board according to claim 1, comprising the second wall portion between at least one adjacent section. Having an outer peripheral wall on the outer periphery of the conductor film,
The outer peripheral wall is
a third wall having the same height as the first wall;
3. The mounting substrate according to claim 1, further comprising a fourth wall portion lower than the third wall portion. 4. The mounting board according to any one of claims 1 to 3, wherein the partition is rectangular. 4. The mounting substrate according to any one of claims 1 to 3, wherein said section is elliptical. The mounting board according to any one of claims 1 to 5, further comprising a through hole penetrating from the top surface of the second wall portion to the back surface of the base material. A mounting substrate according to any one of claims 1 to 6;
a package component having a thermal pad corresponding to the conductor film;
solder filled in the compartment; and
supporting the thermal pad on the first wall;
A connection structure, wherein the thermal pad and the conductor film are connected by the solder. forming a conductor film on an insulating substrate,
forming insulating partition walls on the conductor film for partitioning the conductor film into a plurality of compartments;
The partition wall includes:
a first wall portion disposed at the intersection of the partition walls and having an upper surface at a first height from the upper surface of the conductor film;
and a second wall portion disposed on a side portion of the partition wall separating the adjacent partitions and having an upper surface at a second height lower than the first height. manufacturing method.
of each said compartment,
9. The method of manufacturing a mounting substrate according to claim 8, wherein the second wall is formed between at least one adjacent section. Filling the section of the mounting substrate according to any one of claims 1 to 6 with solder,
supporting the thermal pad of a package component having a thermal pad corresponding to the conductive film by the first wall;
heating the solder,
A method of manufacturing a connection structure, comprising soldering the thermal pad and the conductor film.

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