JP2019165045A - Mounting board and mounting structure - Google Patents

Abstract

To provide a mounting board with which it is possible to efficiently suppress the occurrence of a void.SOLUTION: The mounting board comprises an insulating substrate, a conductor film, and a partition wall. The conductor film is composed of a material that joins with solder, and is laminated on the substrate as a sequence of film. The partition wall is formed on the conductor film and partitions the conductor film into a plurality of segments. The partition wall is composed of a material that does not react with solder, and includes a first wall part of first height from the top face of the conductor film and a second wall part of second height lower than the first height. When solder is supplied to each segment and a thermal pad for a package component is joined upward of the partition wall, solder in each segment connects the thermal pad and the conductor film while being separated from each other. A space whose bottom is defined by the second wall par is created between adjacent solders. A gas generated from the solder is released via this space, and it is possible to suppress the occurrence of a void in the solder.SELECTED DRAWING: Figure 1

Description

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

  A package component obtained by molding an electronic component such as a semiconductor IC (Integrated Circuit) with a resin is widely used. Among such package parts, there are those having a large-area thermal pad on the mounting surface (bottom surface) in addition to terminals for electrical signals. This thermal pad is soldered to the thermal land of the circuit board to form a mechanism for radiating heat generated in the electronic component to the circuit board side.

  In the soldering of the thermal pad and the thermal land, since the solder joint surface has a large area, a gas generated during heating may remain in the solder and a void (cavity) may be generated. If there is a void, there is a problem that heat dissipation, bonding strength, reliability, and the like are lowered.

  Therefore, a structure of a thermal land in which voids are less likely to occur has been proposed. For example, Patent Document 1 discloses a technique for dividing a thermal land into a plurality of regions by a resist. According to this technique, since the area | region where a solder continues becomes small, the gas generated during the heating becomes easy to escape from the solder, and the generation of voids can be suppressed.

  Patent Document 2 discloses a technique for dividing a region to be coated with solder by forming a slit through which a substrate surface is exposed in a conductive layer of a thermal land. According to this technique, similarly to the technique of Patent Document 1, the area where the solder continues is reduced and the gas is easily released. In addition, since there is a path for gas to escape through the slit portion without solder, the generation of voids can be suppressed.

JP 2002-026468 A JP 2006-147723 A

  However, in the technique of Patent Document 1, each region is surrounded by a resist wall, and the upper and lower sides are closed by the thermal pad and the thermal land, so that gas generated from each region is released to the outside. There is no route. As a result, the effect of suppressing voids was limited.

  Moreover, in the technique of patent document 2, when the solder flows during heating, the solder applied to the adjacent region may come into contact with each other beyond the slits to be integrated. In such a case, there is a problem that the volume in which the solder is continuous increases and the gas is difficult to escape. In addition, there is a problem that a part where the solders in a plurality of regions are integrated and a part where the solder is separated are formed, and the heat dissipation is biased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mounting substrate that can efficiently suppress the generation of voids in the heat dissipation portion.

  In order to solve the above problems, the mounting substrate includes an insulating base material, a conductor film, and a partition wall. The conductor film is made of a material to be joined with solder, and is laminated as a series of films on the base material. The partition wall is formed on the conductor film and partitions the conductor film into a plurality of sections. The partition wall is made of a material that does not react with solder, and has a first wall portion having a first height from the upper surface of the conductor film and a second wall portion having 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 conductor film in a state of being separated from each other. And the clearance gap where a bottom face is prescribed | regulated by the 2nd wall part is made between adjacent solders. It is possible to suppress the generation of voids in the solder by releasing the gas generated from the solder to the outside through this gap.

  The effect of this invention is providing the mounting board | substrate which can suppress efficiently generation | occurrence | production of the void in a thermal radiation part.

It is a top view which shows the mounting substrate of 1st Embodiment. It is a top view which shows the mounting substrate of 2nd Embodiment. It is sectional drawing which shows the mounting substrate of 2nd Embodiment. It is a top view which shows the package components used for the mounting structure of 2nd Embodiment. It is a top view which shows the mounting structure of 2nd Embodiment. It is sectional drawing which shows the mounting structure in 2nd Embodiment. It is a top view which shows an example of the flow of the gas of 2nd Embodiment. It is a top view which shows the mounting substrate of 3rd Embodiment. It is sectional drawing which shows the mounting board | substrate of 3rd Embodiment. It is a top view which shows the mounting substrate of 4th Embodiment. It is a top view which shows the mounting substrate of 5th Embodiment. It is a top view which shows the mounting substrate of 6th Embodiment. It is sectional drawing which shows the mounting substrate of 6th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the preferred 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 is 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. The mounting substrate has a base material 1, a conductor film 2, and a partition wall 3.

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

  The conductor film 2 is laminated on the substrate 1 as a series of films. The conductor film 2 is excellent in solder wettability and is formed of a material that 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 includes 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 formed of a material that does not react with solder and has poor solder wettability.

  With the above configuration, each partition partitioned by the partition wall 3 has a bottom surface formed by the conductive film 2 that can be joined to solder and a space surrounded by the partition wall 3 that does not react with 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 thermal pads, the conductor film 2 and the solder disposed in each compartment are separated from each other. Connect. And the clearance gap where a bottom face is prescribed | regulated by the 2nd wall part 3b is made between the solder of a division and the solder of an adjacent division. When 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, generation of voids in the solder can be suppressed.

  As described above, in the mounting substrate of this embodiment, the generation of voids in the heat radiating portion can be efficiently suppressed.

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

  3A is a cross-sectional view showing a cross section taken along the line AA ′ of FIG. 2, and FIG. 3B is a cross-sectional view showing a cross section taken along the line BB ′ of FIG.

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

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

  The terminal land 140 is a conductor for connecting to the terminal of the package component. The terminal land 140 can be formed of the same conductor as the 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 includes 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 wall portion is disposed at the intersection of the partition walls, and the second wall portion is disposed at the side portion. The partition wall 130 is formed using a material that has poor solder wettability and does not react with solder. For example, a solder resist can be used as the material of the partition wall.

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

  FIG. 4 is a plan view showing the package component 200 mounted on the mounting substrate 100. The package component 200 includes a mold 210 that seals an electronic component (not shown), a terminal 220 that is connected to the electronic component, and a thermal pad 230. The terminal 220 is a contact for connecting an electronic component and an external circuit, and the thermal pad 230 is for thermally connecting to an external heat radiating plate or the like to dissipate heat generated by the electronic component.

  FIG. 5 is a plan view showing a mounting structure in which the package component 200 is solder-connected to the mounting substrate 100. In this example, the thermal land 120 and the thermal pad 230 have the same outer shape. Both connecting portions are partitioned by a partition wall 130 into a plurality of (here, 12) sections. And the 1st wall part 130a is arrange | positioned in the cross | intersection part of the partition wall 130, and the 2nd wall part 130b is arrange | positioned in the part of the side which partitions off an adjacent division. Although not shown, each compartment is filled with solder to connect the thermal pad 230 and the thermal land 120.

  6A and 6B are cross-sectional views taken along line CC ′ and DD ′ in FIG. Here, the terminal 220 and the terminal land 140 are connected by solder 150, and the thermal pad 230 and the thermal land 120 are connected by solder.

  In the cross section of FIG. 6A, it is the first wall portion 130a that partitions the solder 150 disposed in the adjacent section. Since the partition wall 130 repels the solder 150, the cross section of the solder 150 extends to the full edge of the partition wall 130 at the joint portion with the thermal pad 230 and the thermal land 120, and there is a gap between the partition wall 130 and the intermediate portion. Is done.

  In the cross section of FIG. 6B, the solder 150 in the adjacent section is partitioned by the second wall portion 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 plan view schematically illustrating the gas flow G in the connection structure 300 described above. The solder 150 shown in FIG. 7 is drawn as a cross section at the center in the thickness direction. As described with reference to FIG. 6A, a gap is formed between the solder 150 and the partition wall 130 by the action of the partition wall 130 repelling the solder 150 in the central portion in the thickness direction. Further, a gap 160 having the upper surface of the second wall portion 130b as the bottom surface exists between the solders 150 in adjacent sections. The gas generated in the solder 150, which is hatched in FIG. 7, is released to the outside of the connection structure 300 through these gaps. For this reason, the probability that the gas is trapped in the solder 150 and becomes a void decreases.

(Example 1)
The mounting substrate 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 at a thickness of 100 μm, and a second wall pattern was formed by photolithography. The width of the second wall portion was 0.2 mm. The size of each section was set to 1.4 mm × 1.2 mm.

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

  As described above, according to the present embodiment, the gas generated from the solder can escape to the outside, and the generation of voids can be suppressed.

(Third embodiment)
In the second embodiment, the outer peripheral portion of the thermal land 120 and the thermal pad 230 has a structure in which the space between the two is opened. However, 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 the mounting substrate 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 131 having the same height as the first wall 130a and a fourth wall 131b lower than the third wall 131a. Have. The height of the fourth wall portion 131b can be the same as that of the second wall portion 130b, for example, 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 the mounting substrate 101, a gap corresponding to the fourth wall portion is formed on the outer peripheral portion. Through this gap, the gas can be discharged to the outside. In FIG. 8, the gas G generated by the virtually placed solder 150 is schematically shown as a gas flow G released through the gap.

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

  As described above, according to the present embodiment, it is possible to suppress the generation of voids by providing a path through which gas escapes while providing a wall that prevents the solder from flowing out from the outer peripheral portion.

(Fourth embodiment)
In the first to third embodiments, the second wall portion is provided between all adjacent sections to secure the gap, but the gap does not necessarily have to be between all the sections. For example, as shown in FIG. 10, the second wall portion may be provided between adjacent sections in the vertical direction in the figure, and not provided on the left and right sides in the figure.

  In the case of such a configuration, it is sufficient that the second wall portion 130b and the fourth wall portion 131b are continuously arranged 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 can be any layout that satisfies the above conditions.

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

(Sixth embodiment)
FIG. 12 is a plan view showing a mounting substrate 103 according to the sixth embodiment. In the mounting substrate 103 of the present embodiment, a through hole 170 penetrating from the upper surface of the second wall portion 130b to the back surface of the substrate 110 is provided in the second wall portion 130b.

  FIG. 13 is a cross-sectional view taken along the line II ′ of FIG. As shown in FIG. 13, the through hole 170 penetrates up to the upper surface of the second wall portion 130 b and the back surface of the base material 110. Since the gas generated by the solder can escape to the outside through the through hole 170, the gas can be efficiently released. As a result, generation of voids can be suppressed.

  The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above embodiment. That is, the present invention can apply various modes that can be understood by those skilled in the art within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1,110 Base material 2 Conductor film 3,130 Partition wall 100,101,102,103 Mounting board 120 Thermal land 130a 1st wall part 130b 2nd wall part 131 Peripheral wall 140 Terminal land 150 Solder 160 Clearance 170 Through-hole 200 Package parts 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 dividing the conductor film into a plurality of sections;
The partition wall is
A first wall having an upper surface at a first height from the upper surface of the conductor film;
And a second wall having an upper surface at a second height lower than the first height. Each said compartment
The mounting board according to claim 1, wherein the second wall portion is provided between at least one adjacent section. 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;
The mounting board according to claim 1, further comprising: a fourth wall portion lower than the third wall portion. The mounting substrate according to any one of claims 1 to 3, wherein the section is rectangular. The mounting substrate according to any one of claims 1 to 3, wherein the section is elliptical. The mounting substrate according to claim 1, further comprising a through hole penetrating from an upper surface of the second wall portion to a back surface of the base material. The 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 with the first wall,
The connection structure, wherein the thermal pad and the conductor film are connected by the solder. Form a conductor film on an insulating base material,
On the conductor film, an insulating partition wall that divides the conductor film into a plurality of sections is formed,
In the partition wall,
A first wall having an upper surface at a first height from the upper surface of the conductor film;
And forming a second wall portion having an upper surface at a second height lower than the first height. Of each said compartment,
The method for manufacturing a mounting substrate according to claim 8, wherein the second wall portion 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,
The thermal pad of a package component having a thermal pad corresponding to the conductor film is supported by the first wall portion,
Heating the solder,
A method for producing a connection structure, wherein the thermal pad and the conductor film are connected by solder.

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