JP2016092123A - Electronic component unit and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component unit which is light-weight and achieves excellent vibration resistance, and to provide a manufacturing method of the electronic component unit.SOLUTION: An electronic component unit 1 has: a printed circuit board 2; an electronic component 3 fixed onto the printed circuit board 2 at a base end 31 side; a housing 4 housing the printed circuit board 2 and the electronic component 3; and a foamed resin 5 injected into the housing 4. The invention relates to the electronic component unit 1 and a manufacturing method of the electronic component unit 1. A tip 32 side of the electronic component 3 is fixed to the housing 4 through the foamed resin 5. The foamed resin 5 closes a hole part 41 provided in the housing 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic component unit having a printed circuit board including an electronic component and a housing for housing the printed circuit board, and a method for manufacturing the same.

  2. Description of the Related Art In recent years, an electronic component unit having a printed circuit board on which electronic components are mounted and a housing that accommodates the printed circuit board is used not only in various electronic devices but also in various technical fields such as portable terminals and automobiles. In the electronic component unit, the electronic component is fixed on the printed circuit board with solder, an adhesive, or the like (see Patent Document 1).

JP 2009-88048 A

  However, the electronic component unit in which only the base end side of the electronic component is fixed on the printed circuit board has insufficient vibration resistance. That is, there is a possibility that the joint portion may be fatigued and destroyed due to vibration of the front end side of the electronic component that is not fixed due to external impact or the like. In order to improve vibration resistance, the entire electronic component can be sealed with resin or the like, but in this case, there is a problem that the weight of the electronic component unit is increased.

  The present invention has been made in view of such a background, and intends to provide an electronic component unit that is lightweight and excellent in vibration resistance, and a method for manufacturing the same.

One embodiment of the present invention is a printed circuit board;
An electronic component having a proximal end fixed on the printed circuit board;
A housing for housing the printed circuit board and the electronic component;
Having a foamed resin injected into the housing;
The foamed resin is in an electronic component unit characterized in that the front end side of the electronic component is fixed to the housing via the foamed resin and a hole provided in the housing is closed.

In another aspect of the present invention, in the method of manufacturing the electronic component unit,
A method of manufacturing an electronic component unit, characterized by injecting a foamable resin into the casing containing the printed circuit board and the electronic component from the hole, and curing the foamable resin while foaming the casing in the casing. is there.

  In the electronic component unit, as described above, the leading end side of the electronic component is fixed to the housing with the foamed resin. Therefore, for example, even if the electronic component is a tall component, it is possible to suppress the tip of the electronic component from vibrating greatly due to an external impact or the like. As a result, it is possible to prevent damage to the joint between the base end side of the electronic component and the printed circuit board due to vibration, and to prevent fatigue failure. That is, the electronic component unit can exhibit excellent vibration resistance.

  In the electronic component unit, a foamed resin having a relatively small specific gravity is used for fixing the electronic component and the housing. Furthermore, it is only necessary that the tip side of the electronic component is fixed with foamed resin, and it is not necessary to cover the entire electronic component with foamed resin, and it is not necessary to fill the entire space in the housing with foamed resin. The amount of resin can be reduced. For this reason, it is possible to reduce the weight and material cost of the electronic component unit.

  Further, the housing has a hole, and foamed resin can be injected into the housing from the hole when the electronic component unit is manufactured. In the electronic component unit, the hole provided in the housing is closed with foamed resin. Therefore, it is possible to prevent foreign matters from entering the electronic component unit from the outside. Therefore, the electronic component unit is excellent in dust resistance and the like.

  In the manufacture of an electronic component unit, a foamable resin is injected from a hole into a housing that accommodates a printed circuit board and electronic components, and the foamable resin is cured while being foamed in the housing. Thereby, while the foamed resin fixes the front end side of an electronic component, the electronic component unit which closed the hole of the housing | casing can be manufactured.

FIG. 3 is a cross-sectional view of the electronic component unit according to the first embodiment. FIG. 3 is a partial enlarged cross-sectional view of a joint portion between an electronic component and a printed board in the electronic component unit according to the first embodiment. Explanatory drawing which shows the manufacturing process of the electronic component unit in Example 1. FIG. Sectional drawing of the electronic component unit in Example 2. FIG. Sectional drawing of the electronic component unit in the comparative example 1. FIG. It is sectional drawing of the electronic component unit in the comparative example 2, Comprising: When the adhesive agent with a high viscosity is used (a), When the adhesive agent with a low viscosity is used (b).

Next, a preferred embodiment of the electronic component unit will be described.
Examples of the foamed resin include a thermosetting resin foamed with a physical foaming agent or a chemical foaming agent. As the thermosetting resin, for example, urethane resin, epoxy resin, phenol resin, unsaturated polyester resin, melamine resin and the like can be used.

  The electronic component has a proximal end fixed to the printed circuit board and a distal end fixed to the housing via a foamed resin. In this specification, the base end in the electronic component is an end on the side fixed to the printed circuit board, and the tip is an end located on the opposite side of the base end.

  One or two or more electronic components may be mounted on the printed circuit board. When a plurality of electronic components are mounted, it is only necessary that the tip side of at least one of these electronic components is fixed with foamed resin. In particular, for example, the front end side of a tall electronic component such that the relationship between the maximum width W at the end surface on the base end side of the electronic component and the maximum height H of the electronic component is H / W> 0.5 is made of foamed resin. It is preferably fixed. Such a tall electronic component is likely to vibrate at the tip due to external impact, so that the effect of improving the vibration resistance by fixing the tip of the electronic component with the foamed resin as described above becomes remarkable. From the same viewpoint, it is preferable to fix the tip of the electronic component with H / W> 1 and more preferably H / W> 1.5 with foamed resin. Moreover, a part of the printed circuit board may be exposed to the outside of the housing, and the electronic component unit may have an electronic component that is exposed to the outside of the housing.

  In the electronic component unit, it is only necessary that at least the tip of the electronic component is fixed with foamed resin. Preferably, the part from the front-end | tip of an electronic component to 1/2 or less of the height of an electronic component is fixed by being covered with foaming resin. In this case, since the amount of the foamed resin can be reduced while securing the vibration resistance of the electronic component unit, further weight reduction and cost reduction can be achieved. Furthermore, in this case, it is possible to prevent the foamed resin from leaking out of the housing when the electronic component unit is manufactured.

The expansion ratio and density of the foamed resin can be arbitrarily set. Specifically, the density of the foamed resin can be set in the range of 0.02 to 0.5 kg / m ³ by adjusting the expansion ratio, for example. In this case, the vibration resistance of the electronic component unit can be sufficiently increased and a sufficient weight can be reduced. Further, if the density of the foamed resin is further reduced within the above range, the electronic component unit can be further reduced in weight. Further, when the density of the foamed resin is further increased, it is possible to further prevent foreign matters from entering from the hole of the housing. Furthermore, it becomes possible to improve waterproofness.

Example 1
Next, an electronic component unit according to an embodiment will be described with reference to the drawings.
As shown in FIG. 1, the electronic component unit 1 of this example includes a printed circuit board 2, an electronic component 3, and a housing 4 that accommodates them. The electronic component unit 1 also has a foamed resin 5 injected into the housing 4. In the electronic component unit 1, a hole 41 is provided in the housing 4. The foamed resin 5 fixes the tip 32 side of the electronic component 3 to the housing 4 through the foamed resin 5 and closes the hole 41 of the housing 4. Hereinafter, the electronic component unit 1 of this example will be described in detail.

  The electronic component unit 1 of this example is specifically an on-vehicle electronic control unit (ECU). The printed board 2 is made of a general glass epoxy board, and a plurality of electronic components 3a, 3b, 3c, and 3d are mounted on both sides thereof. The electronic components 3a, 3b, and 3c are various electronic components mounted on a printed circuit board, and the electronic component 3d is an external connection terminal (connector). The electronic components 3a and 3b are aluminum electrolytic capacitors, and are made of tall components.

  As for each electronic component 3, the base end 31 side is joined to the printed circuit board 2 with solder, an adhesive agent, etc., as for all. As shown in FIG. 2, the printed circuit board 2 includes a resin substrate 21 and a circuit 22 made of Cu formed thereon, and the electronic component 3 is electrically connected to the circuit 22 and is formed on the printed circuit board 2. It is fixed.

  As shown in FIG. 1, the printed circuit board 2 and the electronic components 3 a, 3 b, and 3 c are accommodated in the housing 4, and the end of the electronic component 3 d is exposed from the housing 4. Of the electronic components housed in the housing 4, the vertical length from the mounting surface of the printed circuit board 2 is relatively large, and the tall electronic components 3 a and 3 b are covered with the foamed resin 5 on the tip 32 side. Yes. These electronic components 3 a and 3 b are fixed to the housing 4 via the foamed resin 5. The foamed resin 5 is injected from a hole 41 provided in the housing 4, fixing the tip 32 side of the electronic components 3 a and 3 b and closing the hole 41 of the housing 4. The foamed resin 5 is made of urethane foam resin. The space in the housing 4 is not completely filled with the foamed resin 5, and there is a space 40 into which the foamed resin 5 is not injected.

  Next, a method for manufacturing the electronic component unit 1 of this example will be described. First, as shown in FIG. 3A, a printed circuit board 2 on which a plurality of electronic components 3 are mounted is accommodated in a housing 4. The housing 4 is composed of two members (not shown), and these two members are joined together with the electronic component 3d sandwiched between them, as shown in FIG. It is housed in the body 4. In the housing 4, the base end 31 of the electronic component 3 is fixed to the printed circuit board 2. On the other hand, the tip 32 of the electronic component 3 is an open end that is not joined to the inner wall of the printed circuit board 2 or the housing 4. There is a gap between the tip 32 of the electronic component 3 and the inner wall of the housing 4. The size of the gap can be arbitrarily designed, but it is preferable to make it as small as possible from the viewpoint of miniaturization of the electronic component unit 1. In this example, among the electronic components 3, the electronic components 3 a and 3 b have the maximum width W and the maximum height H (the electronic components 3 in the vertical direction from the mounting surface 20 on the printed circuit board 2). H / W> 1.5.

  As shown in FIG. 3A, in the direction perpendicular to the mounting surface 20 of the electronic components 3a and 3b on the printed circuit board 2, that is, in the height H direction of the electronic components 3a and 3b, the electronic components 3a and 3b A hole 41 is provided in the housing 4 on the extension line L from the tip 32. In this example, as described above, the hole portions 41 are provided on the extension lines L of the tip 32 in the two tall electronic components 3a and 3b.

  Next, as shown in FIG. 3B, the foamable resin 50 was injected into the housing 4 from the hole 41. The foamable resin 50 is a material that contains, for example, a resin component and a foaming agent and becomes a foamed resin by foaming. In order to obtain a foamed resin composed of a urethane foamed resin as in this example, a two-component mixed material composed of, for example, a polyol raw material and an isocyanate raw material can be used. The foamable resin 50 is injected from the hole 41 and is cured while being foamed in the housing 4. Accordingly, the tip 32 side of the electronic components 3a and 3b is covered with the foamed resin 5, and the hole resin 41 is filled with the foamed resin 5 to close the hole 41 (see FIG. 1). At this time, by adjusting the injection amount of the foamable resin 50 and the expansion ratio, the foam resin 5 is contained in the housing 4 while the tips 32 of the relatively tall electronic components 3a and 3b are covered with the foam resin 5. It is possible to ensure a sufficient space 40 that is not filled.

Next, the effect of the electronic component unit 1 of this example is demonstrated using drawing.
As shown in FIG. 1, in the electronic component unit 1 of this example, the tips 32 of the tall electronic components 3 a and 3 b are fixed to the housing 4 by the foamed resin 5. Therefore, it can suppress that the front-end | tip 32 of the electronic components 3a and 3b vibrates greatly by the impact etc. from the outside. As a result, it is possible to prevent damage to the bonding between the printed circuit board 2 and the base end 31 side of the electronic components 3a and 3b due to vibration. That is, the electronic component unit 1 is excellent in vibration resistance. In particular, as in this example, the tips 32 of the tall electronic components 3a and 3b such that the relationship between the maximum width W and the maximum height H on the end surface on the base end 31 side is L / W> 1.5. It is preferable that the side is fixed by the foamed resin 5 (see FIGS. 1 and 3). In this case, if the foamed resin 5 is not provided, the tip 32 of the electronic component 3a, 3b is likely to vibrate due to an external impact. As a result, the effect of improving vibration resistance becomes remarkable. Moreover, as in this example, the foamed resin 5 is preferably a urethane foam resin. In this case, since the foamed resin 5 exhibits excellent flexibility, the vibration resistance of the electronic component unit 1 can be further improved.

  In the electronic component unit 1, for example, a foamed resin 5 having a specific gravity smaller than that of a non-foamed resin is used for fixing the electronic components 3 a and 3 b and the housing 4. Furthermore, it is only necessary that the tip 32 side of the electronic components 3a and 3b is fixed with the foamed resin 5, and it is not necessary to cover the entire electronic components 3a and 3b with the foamed resin 5, and the entire space in the housing 4 is foamed. There is no need to fill with resin 5. Therefore, the amount of the foamed resin 5 can be reduced, and the electronic component unit 1 can be reduced in weight and the material cost can be reduced. A space 40 that is not filled with the foamed resin 5 can be formed in the housing 4. From the viewpoint of weight reduction and cost reduction, the ratio of the foamed resin 5 to the space in the housing 4 in the electronic component unit 1 is preferably 50% by volume or less, and more preferably 30% by volume or less. preferable. In other words, the space 40 is preferably present in the housing 4 in an amount of 50% by volume or more, and more preferably 70% by volume or more.

  Moreover, the housing | casing 4 has the hole part 41, and the foaming resin 5 can be formed by inject | pouring the foamable resin 50 into the housing | casing 4 from the hole part 41 at the time of manufacture of the electronic component unit 1. FIG. . In the electronic component unit 1, the hole 41 provided in the housing 4 is closed by the foamed resin 5. Therefore, it is possible to prevent foreign matters from entering the electronic component unit 1 from the outside. Therefore, the electronic component unit 1 is also excellent in dust resistance and the like. Furthermore, waterproofness can be imparted by adjusting the density of the foamed resin.

  Moreover, it is preferable that the hole part 41 is provided on the extension line L of the front-end | tip 32 of the electronic components 3a and 3b fixed by the foamed resin 5. FIG. In this case, when the foamable resin 50 is injected from the hole 41 when the electronic component unit 1 is manufactured, the tip 32 of the electronic components 3a and 3b can be easily fixed by the foamed resin 5. Specifically, as shown in FIGS. 3A and 3B, the printed board 2 and the electronic board 2 are accommodated so that the electronic components 3a and 3b are on the lower side in the vertical direction and the hole 41 is on the upper side. The foamable resin 50 is injected from the hole 41 with the casing 4 to be installed. Thereby, the foamable resin 50 is cured while bulging downward in the vertical direction by its own weight, and the foamed resin 5 is formed. Therefore, when the hole 41 serving as the injection port for the foamable resin 50 is positioned on the extension line L of the tip 32 of the electronic component 3a, 3b as described above, the direction in which the foamable resin 50 swells (vertical direction). Since the tips 32 of the electronic components 3a and 3b are positioned downward), the tips 32 of the electronic components 3a and 3b can be more reliably fixed. Even if the extension line L and the center of the hole 41 do not intersect with each other, it is only necessary that a portion where the extension line L from the tip 32 of the electronic component 3a, 3b intersects with the hole 41 exists. For example, the extension line L and the outer edge of the hole 41 may intersect. In addition, when the tip 32 of the electronic component 3a, 3b is, for example, a flat surface and a plurality of extension lines L are assumed from the tip 32, there is a place where any one extension line L and the hole 42 intersect. If you do.

  Moreover, although the electronic component unit 1 of this example is for in-vehicle use, the electronic component unit having the same configuration can be used for portable equipment in addition to the in-vehicle electronic component by taking advantage of its excellent vibration resistance and light weight. Is also suitable. Particularly preferably, it is for in-vehicle use, and is preferably mounted on automobiles including motorcycles and cars. In such applications, engine vibration, impact transmitted from tires, and the like are applied to the electronic component unit 1 continuously or intermittently over a long period of time. Since the electronic component unit 1 of this example can exhibit excellent vibration resistance against such vibrations and shocks, the above-described effect of being excellent in vibration resistance becomes remarkable. In addition, against the background of soaring fuel prices, recent automobiles are required to further improve fuel efficiency. Since the electronic component unit 1 of this example can be reduced in weight as described above, it can also contribute to an improvement in fuel consumption. Furthermore, the electronic component unit 1 of this example can also improve waterproofness as needed. In this case, it becomes more suitable for in-vehicle use where water intrusion is assumed.

  As described above, according to this example, it is possible to manufacture the electronic component unit 1 that is lightweight and has excellent vibration resistance.

(Example 2)
This example is an example of an electronic component unit using a casing having a rib portion.
As shown in FIG. 4, the electronic component unit 1 of the present example has a rib portion 42 erected on the inside of the housing 41. The rib portion 42 is formed integrally with the housing 4. The foamed resin 5 injected into the housing 4 is blocked by the rib portion 42.

  The formation position of the rib part 42 is arbitrary, but it can be formed at a position spaced apart from a hole 41 provided in the housing 4, for example. By forming the rib portion 42 near the hole portion 41, the expansion of the foamable resin injected from the hole portion 41 during foaming is further suppressed, and the electronic component 3a can be achieved even if the amount of the foamable resin added is reduced. 3b can be securely fixed by the foamed resin 5. Moreover, since the expansion of the foamed resin 5 can be suppressed, the space 40 in the housing 4 can be made wider. As a result, the electronic component unit 1 can be further reduced in weight. Other functions and effects are the same as those of the first embodiment. In this example and comparative examples 1 and 2 to be described later, the same reference numerals as those in the first embodiment indicate the same configurations as those in the first embodiment, and the preceding description is referred to.

(Comparative Example 1)
This example is an example of an electronic component unit in which the base end side of the electronic component is fixed and the tip is opened.
As shown in FIG. 5, in the electronic component unit 8 of this example, the base end 31 side of the tall electronic components 3 a and 3 b is fixed to the printed circuit board 2 with an adhesive 81. The tips 32 of the electronic components 3a and 3b are not fixed anywhere in the electronic component unit 8 and are open ends. Moreover, since it is not necessary to inject a foamed resin from the outside like Example 1, the hole part is not formed in the housing | casing 4. FIG. Other configurations are the same as those of the first embodiment.

  In the electronic component unit 8 of this example, as described above, the tips 32 of the tall electronic components 3a and 3b are not fixed. Therefore, the tips of the electronic components 3a and 3b vibrate due to external impact. As a result, the bonding between the electronic components 3a, 3b and the printed circuit board 2 on the base end 31 side is impaired, and fatigue failure may occur. On the other hand, in the electronic component unit 1 according to the first and second embodiments, since the tips 32 of the electronic components 3a and 3b are fixed to the casing 4 by the foamed resin 5, the tips 32 of the electronic components 3a and 3b. (See FIGS. 1 and 4). As a result, fatigue failure can be prevented.

(Comparative Example 2)
This example is an example of an electronic component unit that attempts to fix the tip of the electronic component using an adhesive.
As shown in FIG. 6, the electronic component unit 9 of this example has the same configuration as that of Example 1 except that the adhesive 91 is injected from the hole 41 of the housing 4 instead of the foamed resin. Have. In order to fix the tips of the electronic components 3a and 3b with the adhesive 91, it is necessary to consider various conditions such as the viscosity, amount, and quick drying property of the adhesive 91. However, it is very difficult to fix the tip 32 of the electronic component 3 and the housing 4 with the adhesive 91 injected from the hole 41.

  For example, when the viscosity of the adhesive 91 is increased, as shown in FIG. 6A, the adhesive 91 may not be spread over the entire tip 32 of the electronic components 3a and 3b. On the other hand, as shown in FIG. 6B, when the viscosity of the adhesive 91 is lowered, the adhesive 91 may flow down from the tips 32 of the electronic components 3a and 3b onto the printed circuit board 2.

  Thus, by injecting the adhesive 91 from the hole 41 of the housing 4, it is very difficult to close the hole 41 while fixing the tips 32 of the tall electronic components 3 a and 3 b. On the other hand, as in the first and second embodiments, the tip 32 of the electronic components 3a and 3b is fixed by the foamed resin 5, thereby fixing the tip 32 and closing the hole 41.

DESCRIPTION OF SYMBOLS 1 Electronic component unit 2 Printed circuit board 3 Electronic component 4 Case 41 Hole part 5 Foamed resin

Claims (6)

A printed circuit board (2);
An electronic component (3) whose base end (31) side is fixed on the printed circuit board (2);
A housing (4) for housing the printed circuit board (2) and the electronic component (3);
A foamed resin (5) injected into the housing (4);
The foamed resin (5) fixes the tip (32) side of the electronic component (3) to the casing (4) through the foamed resin (5) and is provided in the casing (4). The electronic component unit (1), wherein the hole (41) is closed.   The electronic device according to claim 1, wherein the hole (41) of the housing (4) is provided on an extension line (L) of the tip (31) of the electronic component (3). Part unit (1).   The casing (4) has a rib portion (42) standing on the inner side of the casing (4), and the foamed resin (5) injected into the casing (4) is The electronic component unit (1) according to claim 1 or 2, wherein the electronic component unit (1) is dammed by the rib portion (42).   The electronic component unit (1) according to any one of claims 1 to 3, wherein the foamed resin (5) is a urethane foam resin.   The electronic component unit (1) according to any one of claims 1 to 4, wherein the electronic component unit (1) is for vehicle use. In the manufacturing method of the electronic component unit (1) of any one of Claims 1-5,
The foamable resin (50) is injected from the hole (41) into the housing (4) that accommodates the printed circuit board (2) and the electronic component (3), and the foamable resin (50) is placed in the housing. A method for producing an electronic component unit (1), comprising: curing while foaming in a body (4).

Images