JPH0423343Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an electronic circuit device coated with a thermoplastic resin, and in particular to an improvement of an element arrangement indicating paste portion that is printed and coated on a substrate.

[Prior Art] Electronic circuit elements used in various control devices usually have a structure in which the main body is protected by a plastic mold for airtight sealing and connected to a printed circuit board with a large number of pins.

Figure 5 shows an IC as such an electronic circuit element.
A dual in-line package (DIP) is shown, in which A is a top view, B is a front view, and C is a side view.

As is clear from the figure, the DIP has an IC storage part 10 that stores an IC inside, and an L-shaped DIP that protrudes laterally from the IC storage part 10 and is electrically connected to a circuit board (not shown). A lead pin 12 is provided.

Then, the IC package is fixed onto the printed circuit board by passing the lead pins 12 through through holes provided in the printed circuit board and performing soldering or the like.

By the way, electronic circuit elements such as ICs have relatively low heat resistance, and in order to minimize heat transfer to the electronic circuit element body when, for example, soldering lead pins, the electronic circuit element body is attached to a printed circuit board. It is configured to float slightly more.

That is, in the illustrated example, the lead pin 12 has a thin tip and a tapered portion 12a approximately in the center.
By providing the tapered part 12a, the part up to the tapered part 12a is inserted into the through hole on the printed circuit board, and the predetermined positioning and electrical connection with the printed board are performed. It can be held in a floating state.

Furthermore, if waterproofness, dustproofness, etc. are particularly required for the printed circuit board, for example, when the circuit board is used for electronic equipment for vehicles, it is necessary to , coating is performed using acrylic resin or the like.

The electronic circuit device composed of the electronic circuit element and the printed circuit board as described above has the advantage that it is possible to use a highly functional electronic device even under a somewhat adverse environment.

[Problems to be solved by the invention] Problems of the prior art However, as mentioned above, when the printed circuit board on which the electronic circuit element is mounted is coated with plastic resin, the gap between the main body of the electronic circuit element and the printed circuit board is reduced. Since the coating resin penetrates and hardens, thermal or mechanical stress distortion is applied to the lead pins, which poses a problem in that the bonding condition between the lead pins and the substrate may deteriorate.

However, in conventional devices, the intrusion of the coating resin could only be prevented by adjusting and controlling the dimensions of the electronic circuit element main body and the viscosity of the coating resin.

Therefore, it is not possible to completely prevent the coating resin from entering, so even if the bonding force between the lead pin and the printed circuit board is increased by clinching or double-sided soldering, the problem of reducing stress and strain remains. .

Purpose of the invention The present invention was devised in view of the problems of the prior art described above, and its purpose is to minimize the occurrence of stress and strain even when resin coating is applied to a printed circuit board on which electronic circuit elements are mounted. The purpose of the present invention is to provide an electronic circuit device that can perform the following steps.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the electronic circuit device for thermoplastic resin coating according to the present invention has an electronic circuit device mounted on a printed circuit board, with its main body part facing away from the mounting surface of the printed circuit board. In electronic circuit devices for thermoplastic resin coating, in which the electronic circuit device is mounted in a separated state and a plastic resin coating is applied after mounting, the upper surface of the layout display paste that is printed and applied to show the element layout diagram on the printed circuit board is The paste is formed to be thicker than the gap length between the electronic circuit element body and the printed circuit board mounting surface so that the paste adheres to the entire periphery of the bottom surface of the electronic circuit element body. do.

[Function] As described above, the present invention is characterized by forming the paste thickly so that the upper surface of the placement display paste printed and applied on the printed circuit board is in close contact with the main body of the mounted electronic circuit element. It is possible to effectively prevent the coating resin from entering the gap between the electronic circuit element main body and the printed circuit board.

As a result, it is possible to reduce the stress strain applied to the lead pins due to the hardening of the coating resin that has penetrated, and it is possible to significantly improve the stability of the bonding of the lead pins to the printed circuit board.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

First Embodiment FIG. 1 shows a side sectional view of an electronic circuit device for thermoplastic resin coating according to the first embodiment of the present invention, and shows the case where an IC package is used as the electronic circuit element. . In this figure, parts corresponding to those in FIG. 5 are designated by the same reference numerals, and their explanations will be omitted.

The IC package 100 is connected and fixed to a predetermined position on the mounting surface of the printed circuit board 14 by L-shaped lead pins 12 protruding from the IC housing part 10.
The fixation is such that the lead pin 12 is attached to the printed circuit board 14.
is inserted into the through hole provided in the printed circuit board 1.
This is done by fixing the tip of the lead pin 12 protruding from the back surface of the lead pin 12 with solder 16.

A coating resin 18 is applied to the front and back surfaces of the printed circuit board 14 to ensure environmental resistance.

The feature of the present invention lies in the placement display paste 20 that is printed and applied on the mounting surface of the printed circuit board 14, and the placement display paste 20 is spread between the bottom of the IC housing section 10 and the mounting surface of the printed circuit board 14. The upper surface of the placement display paste 20 is formed to be in close contact with the bottom surface of the IC housing section 10 when the IC package 100 is attached.

FIG. 2 is a top view of the printed circuit board 14,
The placement display paste 20 is shown by a solid line, and the IC package 100 mounted at that location is shown by a chain line.

As shown in this figure, the layout display paste 20 is
A frame indicating the placement position of the IC package 100 and the IC
A character indicating the type of package is displayed (in this example, it is indicated as MB0000). According to this example, even if thermoplastic resin coating is applied after the IC package 100 is mounted on the printed circuit board 14, , coating resin 18
Since the placement display paste 20 functions as a spacer, the IC housing part 10 and the printed circuit board 14
The placement display paste 20 does not intrude into the gap between the display paste 20 and the display paste 20.

Therefore, when the coating resin 18 that has entered the bottom of the IC housing section 10 hardens, thermal or mechanical stress distortion is applied to the lead pins 12.
There is no fear that the durability of the solder 16 will be affected.

Second Embodiment FIG. 3 shows a side sectional view of an electronic circuit device for thermoplastic resin coating according to a second embodiment of the present invention, and similar elements to those of the device in FIG. Reference numerals are given and explanations thereof are omitted.

The difference between this embodiment and the first embodiment is that the placement display paste 20 is formed so as to be in close contact with the periphery of the lower side surface of the IC storage section 10 instead of on the inside of the bottom surface of the IC storage section 10. .

FIG. 4 shows a top view of the printed circuit board 14, in which the placement display paste 20 shown in FIG. 3 printed and applied on the mounting surface is shown as a solid line, and the IC package 100 mounted thereon is It is shown by a dashed line.

According to this embodiment, the layout display paste 20 is
It is formed in a dam shape on the side of the IC storage part 10,
The coating resin 18 can penetrate into the gap between the IC housing part 10 and the printed circuit board 14 more completely than the device of the first embodiment.

That is, in the first embodiment, since the upper surface of the placement display paste 20 is placed in contact with the bottom surface of the IC storage section 10, the placement display paste 2
0 must be placed so as to be in close contact with the edge of the bottom side of the IC housing section 10, and if it is placed closer to the inside of the bottom surface than the side edge, the coating resin 18 may penetrate to the position of the placement display paste 20. In contrast, the second
In the embodiment, since the placement display paste 20 is in contact with the side surface, the coating resin 18 is completely prevented from entering the bottom surface of the IC storage section 10.

In addition, in both the first and second embodiments, by using a material with high stress absorption for the placement display paste 20, stress on the lead pins 12, which is a characteristic effect of the present invention, is reduced. More effective distortion reduction can be achieved.

[Effects of the invention] As explained above, according to the electronic circuit device according to the invention, the layout display paste printed and applied on the mounting surface of the printed circuit board is made to adhere closely to the main body of the electronic circuit element to be mounted. By forming the film thickly, it is possible to effectively prevent the coating resin from entering the gap between the electronic circuit element body and the printed circuit board during coating with the thermoplastic resin, thereby preventing the coating resin from curing. Therefore, the stress strain applied to the electronic circuit element can be reduced, and the bonding state between the lead pin and the printed circuit board can be maintained in a good condition.

[Brief explanation of the drawing]

1 is an explanatory diagram of an electronic circuit device for thermoplastic resin coating according to a first embodiment of the present invention, FIG. 2 is a top view of a printed circuit board according to the first embodiment, and FIG.
The figure is an explanatory diagram of an electronic circuit device for thermoplastic resin coating according to the second embodiment of the present invention, and FIG.
FIG. 5, a top view of the printed circuit board according to the embodiment, is an explanatory diagram of the electronic circuit element (IC package). 10...IC storage section, 12...Lead pin, 1
4...Printed circuit board, 16...Solder, 20...
Layout display paste, 100...IC package.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A printed circuit board on which a layout display paste showing an element layout diagram is printed and applied on the element mounting surface, and an electronic circuit element body that protrudes from the body and is electrically connected to the printed circuit board. an electronic circuit element that is mounted on the printed circuit board with the main body part not in contact with the printed circuit board and the printed circuit board mounting surface; and a thermoplastic resin coating after the electronic circuit element is mounted on the printed circuit board. In the electronic circuit device for thermoplastic resin coating, the thickness of the placement indicating paste is adjusted between the printed circuit board mounting surface and the electronic circuit element body so that the upper part of the paste surface is in close contact with the electronic circuit element body. 1. An electronic circuit device for thermoplastic coating, characterized in that the paste is formed thicker than the gap length of the electronic circuit element body, and the placement display paste is formed in close contact within the bottom surface of the electronic circuit element main body and over the entire periphery of the bottom surface. (2) The electronic circuit device according to claim (1) of the utility model registration is characterized in that the layout indicating paste is formed so as to be in close contact with the lower side surface of the electronic circuit element main body and over the entire circumference of the side surface. Electronic circuit device for thermoplastic resin coating.