JP2542974Y2 - Substrate sealing structure - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing structure of a substrate in which a resin is sealed in a housing containing a substrate on which electronic components are mounted.

[0002]

2. Description of the Related Art A board on which electronic components are mounted is housed in a housing, and a resin is sometimes sealed in the housing as a moisture-proof and waterproof means for the electronic components and the like. FIG. 3 shows this sealing structure in a simplified manner. 101 is a substrate, 102 is a housing, and 103 is an electronic component having a lead 131 at the lower part of the main body. The lead 131 is soldered to the substrate 101. Reference numeral 104 denotes an epoxy resin. If the epoxy resin 104 is sealed so as to cover all the electronic components including the electronic component 103 as shown in the figure, waterproofness can be achieved. However, when such an epoxy resin 104 is used, the epoxy resin 10
4 shrinks or expands, causing stress inside the housing. That is, if the value of stress is expressed by an equation, stress = expansion coefficient × temperature change × total length of resin part (L) × elastic coefficient of resin Here, the expansion coefficient means the expansion coefficient of the substrate 101 and the expansion coefficient of the epoxy resin 104. And the difference. Therefore, the stress increases as the difference between the expansion coefficients of the substrate 101 and the epoxy resin 104 increases. The elastic modulus is
The unit is expressed by [force / length] with a coefficient peculiar to the resin.
The stress increases. When stress is generated in the epoxy resin 104 in this manner, stress is applied to the upper part of the main body of the electronic component 103, and the main body tends to move as indicated by an arrow in the drawing. For this reason, for example, a load is applied to the leads 131 of the electronic component 103 and the leads 131 are separated from the substrate 101. Therefore, in order to reduce this stress, a resin having a small elastic modulus is selected from the above equation, or the total length (L) of the resin portion is shortened to reduce the housing 2.
Needed to be smaller.

To solve this problem, Japanese Unexamined Patent Publication No.
2. Description of the Related Art A sealing structure disclosed in Japanese Patent Publication No. That is, as shown in FIG.
2, the housing 102 is divided into a plurality of sections. Note that the same components as those in FIG. 3 are denoted by the same reference numerals. FIG. 5 is a top view thereof. In this way, the total length (L) of the resin portion is divided (L1, L2), so that the stress in each section is reduced. Therefore, the load on the electronic components in each section can be reduced, and the size of the housing 102 can be kept as it is.
That is, the partition plate 105 absorbs the stress.

[0004]

After the epoxy resin 104 flows into the housing 102, the partition plate 105
2, the bottom surface of the partition plate is kept in contact with the substrate 101 until the epoxy resin 104 is hardened in order to temporarily fix the position of the partition plate 105 firmly. For this reason, electronic parts and the like cannot be mounted on a portion of the substrate 101 where the partition plate 105 is in contact, and a space must be provided for that. For example, as shown in FIG. 4 and FIG. 5, the resistor cannot be mounted in an arrangement indicated by a dotted line. In particular, among electronic components, those having leads at the bottom are relatively large, and when such electronic components are mounted, the space in the housing is considerably restricted. Providing the mounting forbidden space 106 makes it very difficult to design a board such as the arrangement of electronic components. In addition, when the thickness of the partition plate is large or the number of the partition plates is large, the problem appears more remarkably.

Accordingly, an object of the present invention is to reduce the resin stress without reducing the size of the housing and to reduce the mounting prohibited space on the board.

[0006]

In order to achieve the above object, the present invention provides an electronic component having a lead in a main body, a board for holding the lead, a housing for accommodating the board, and a housing for accommodating the board. A partition plate provided on the electronic component mounting surface, the partition plate dividing the inside of the housing into at least two or more partitions, and sealing the substrate by injecting a resin into the partition divided by the partition plate In the above sealing structure, the partition plate is provided with a plurality of projections, and the projections are in contact with the substrate.

[0007]

[Action] For electronic components having leads at the bottom of the main body,
The connection between the lead and the substrate is affected because stress is applied to the upper part of the main body. That is, if no stress is applied to at least the upper part of the main body, almost no load is applied to the leads. Therefore, the partition plate of the present invention is made to correspond at least to the upper part of the main body of the electronic component, and a projection is used for contact with the substrate. Therefore, the partition plate can be temporarily fixed firmly by contacting the plurality of projections provided on the partition plate with the substrate without contacting the bottom surface of the partition plate itself with the substrate. The portion of the board that is in contact with the protrusion is a mounting prohibited space.However, since the protrusion is in contact with the substrate in a so-called point-like manner, the area of the board that is in contact with the protrusion is extremely small. Can be smaller. Therefore, a large number of electronic components can be mounted, and the degree of freedom in board design increases accordingly.

[0008]

FIG. 1 is a perspective view showing an example of the substrate sealing structure of the present invention. 1 is a substrate, 2 is a housing for accommodating the substrate 1, 3
Is an electronic component having a lead 32 below the main body 31.
Reference numeral 4 denotes an electronic component other than the electronic component 3, for example, a resistor or a chip component having a lead on the side of the main body. Reference numeral 5 denotes an epoxy resin sealed in the housing 2, and reference numeral 6 denotes a partition plate. The partition plate 6 is composed of a main body 61 and a plurality of thin projections 62, and the tips of the projections 62 are in contact with the substrate 1. The partition plate 6 divides the inside of the housing 2 into four sections.

Next, a description will be given of a process of forming a housing in which a resin is sealed. First, a substrate 1 on which electronic components 3 and 4 are mounted
Is stored in the housing 2, and the liquid epoxy resin 5 is caused to flow into the housing 2. Before the epoxy resin 5 is hardened, the partition plate 6 is inserted and the projections 62 are brought into contact with the substrate 1 so that the partition plate 6 is temporarily fixed firmly so as not to move. When the epoxy resin 5 hardens, the partition plate 6 is fixed. The housing 2 formed in this way is mounted, for example, in a vehicle. Particularly, in a vehicle, since the environmental temperature changes drastically, as described above, when the temperature rises, for example, when the temperature rises, the housing 2 expands to increase the stress. Occur. However, even if such a stress is generated, it is sufficient to view the stress in one section, so that the length of the resin portion can be shortened (L1, L2). Therefore, the stress in each section is smaller than when the partition plate 6 is not provided, and the load on the leads 32 of the electronic component 3 can be reduced while keeping the size of the housing 2 unchanged.

Further, since the portion where the substrate 1 is in contact with the tip of the projection 62, that is, the mounting prohibited space is a point-like shape, it is extremely small, so that more electronic components can be mounted. That is, as shown in FIG. 1, the space between the projections 62 becomes an empty space, so that a chip component, a resistor having a lead on the side of the main body, an IC, or the like can be mounted here. Therefore, for example, as compared with FIG. 4 shown in the prior art, in this example, the resistor 4 can be mounted in an ideal arrangement as shown in FIG. 1, and the degree of freedom in substrate design can be improved.

FIG. 2 is a detailed structural view of the partition plate 6. As shown in FIG.
The main body of the partition plate 61 and the projection 62 are integrally formed. Most of the partition plate 6 is constituted by the main body 61, and the length of the projection 62 is set to, for example, 3 mm or less so as not to be too high. That is, the length of the electronic component 3, which is the shortest among the components mounted on the substrate 1, is at least
And the partition plate main body 61 is configured to overlap at least the upper part of the main body 31 of all the electronic components 3. By doing so, it is possible to reduce the stress applied to the upper part of the main body 31 for all the electronic components 3.

Accordingly, the load on the leads 32 of the electronic component 3 can be reduced while keeping the size of the housing 2 unchanged. In addition, the mounting prohibited space on the substrate 1 can be reduced. Incidentally, the number of the partition plates and the number of the projections can be appropriately changed according to the substrate design.

[0013]

As described above, according to the present invention, the resin stress can be reduced without reducing the size of the housing, and the mounting prohibited space on the board can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a substrate sealing structure showing an example of the present invention.

FIG. 2 is a detailed view of a partition plate 6 showing an example of the present invention.

FIG. 3 is a side view of a substrate sealing structure showing a first conventional example.

FIG. 4 is a side view of a substrate sealing structure showing a second conventional example.

FIG. 5 is a top view of a substrate sealing structure showing a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 3 ... Electronic component 6 ... Partition plate 61 ... Partition plate main body 62 ... Projection

Claims (1)

(57) [Scope of request for utility model registration] An electronic component having a lead in a main body, a substrate for holding the lead, a housing for accommodating the substrate, and provided on an electronic component mounting surface of the substrate, wherein at least the inside of the housing is provided. A partition plate for dividing into two or more partitions, wherein a resin is injected into the partition divided by the partition plate to seal the substrate, and the partition plate has a plurality of projections. A sealing structure for a substrate, wherein the projection is provided and the projection is in contact with the substrate.