JPS60213095A - Electronic circuit device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic circuit device in which an electronic circuit or the like used for electrical equipment is housed in a case and sealed.

(Conventional configuration and its problems) Electronic circuits, such as those used in automobiles, which particularly require high reliability and are easily affected by humidity, pollution, etc., need to be mounted in an airtight structure. Furthermore, if it is an electronic circuit that is to be encapsulated, heat treatment at too high a temperature or application of high pressure will lead to damage, so it is not preferable to use soldering or welding, and adhesives are often used.

Below, with reference to all the drawings, the conventional electronic circuit system ff1F
Let me explain about K.

FIG. 1 is a sectional view showing the structure of a conventional capacitive pressure sensor. In the figure, 1 is a metal case (for example, an aluminum case), 2 metal lids with a thickness of 0.5 Ia, and 3 are adhesives made of thermosetting resin that bond the aluminum case 1 and the lid 2. 4 is solder for sealing the air vent through hole when the adhesive 3 is cured. 6 is a pressure sensing element whose capacitance changes according to the pressure introduced from the pressure introduction hole, and is mounted inside the aluminum case via the holding plate 8, square ring 7, and sealing rubber ring 5. has been done. This is a printed circuit board mounted with a processing circuit that converts the capacitance of nine pressure sensing element parts 6 into electrical signals, and the electrical signal output is taken out by a lead wire 10. The lead wire 10 and the aluminum case 1 are sealed with a thermosetting resin 12 for adhesion via a rubber pusher 11. Note that 13 is metal wire, 14#
It is a rubber bush.

FIG. 2 is an enlarged cross-sectional view of the adhesive portion A (FIG. 1) between the aluminum case 1 and the metal lid 2. As shown in FIG. 2, for example, a medium 311EI
A recess 1a with an IN depth of 3 Wrln is provided, and a metal lid 2 with a thickness of 0.5 rm and a width of 2.5 +a is provided in the recess 1a.
The adhesive 3 made of a thermosetting resin is injected into the recess 1aK, and then heated at 120°C.
, it is configured to be thermally cured in 10 hours.

However, the coefficient of thermal expansion of the aluminum case 1 is 2.
3X10 7℃, the coefficient of thermal expansion of the metal lid 2 is generally 1
3 to 18 x 10/°C, and the thermosetting resin adhesive 3 generally has a coefficient of thermal expansion of about 50 x 10-'/l:: There is a large difference in thermal expansion coefficient between metal and resin. For this reason, in the past, when severe cooling and heating cycles were applied, internal stress was applied alternately in the tensile and compressive directions at the interface between the metal and the resin, resulting in peeling and cranking, through which moisture infiltrated from the outside. This may cause damage to electronic circuits.

(Objective of the Invention) The present invention has been made in view of these conventional drawbacks and is intended to provide a complete electronic circuit device with complete sealing performance and reliability.

(Structure of the Invention) In order to achieve the above object, the present invention includes an inorganic material in an adhesive for bonding a metal case housing an electronic circuit, etc., and a metal lid covering the metal case. The electronic circuit device is constructed using a highly filled epoxy resin with an additive of 6. This structure improves both thermal shock resistance and moisture resistance, and provides an electronic circuit device with a highly reliable sealed structure. It becomes possible to provide circuit devices.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to FIG. 3 of the drawings. Note that a cross-sectional view Vi of a capacitive pressure sensor to which the present invention is applied
Since it is basically the same as in FIG. 1, the explanation here will be omitted.

FIG. 3 is an enlarged sectional view of the adhesive part between the metal case (for example, aluminum case) 1 and the metal lid 2 when the present invention is applied, and the basic configuration is described in detail in the conventional example. It is omitted here.

Further, the same reference numerals as in FIG. 2 indicate the same contents.

In the figure, 15 is a highly filled epoxy resin to which 40% of melt warping force is added.

Figure 4 shows general epoxy resin (curve a) and fused silica 40.
This figure shows the reliability evaluation results of the degree of sealing when bonded with a highly filled epoxy resin 15 (total approximately b). As a test method, a thermal shock cycle test (-40 to 120°C, 30 minutes each) was performed, and as an evaluation method, the inside of the sample 20 was placed in a vacuum pumper 2 as shown in Figure 5.
1, a predetermined degree of vacuum is established, the pulp of the helium generator 22 is opened, helium is sprayed onto the sample 20, and the amount of helium leaked is measured using the helium leak detector device 23. The user's test standard is that the number of thermal shock cycles is 100 cycles, and the criteria for determining pass/fail is I x 10 C because electronic circuit components will have poor characteristics if there is leakage of I x 10 CC/see or more.
C/' sec or higher is considered to be a good product.

According to these results, the sample of general epoxy resin has poor properties at the 50th cycle, but the sample of highly filled epoxy resin 15 containing 40% molten liqueur has poor properties for the first time at the 500th cycle. The effect of using Resin 15 is noticeable. As shown in Figure 3, the coefficient of thermal expansion of the highly filled molding resin 15 containing 40% melting strength is 20 x 107°C, and the aluminum case 1
(Thermal expansion coefficient: 23 x 10 / C) and the metal lid 2 (Thermal expansion coefficient: 13 to 18 x 107° C.) The thermal expansion coefficient is an intermediate value, and the absolute value is also close to that of metal, so it is resistant to thermal shock. This is because it has a highly reliable configuration. To be more specific, the thermal expansion coefficient of the adhesive epoxy resin is 50.
If X10/'C is large, a large internal stress will occur in the tensile direction at the boundary between the metal part and the resin at low temperatures, and conversely, a large internal stress will occur in the compressive direction at high temperatures. Therefore, when cold and hot cycles are applied, large internal stresses are applied alternately in the tensile and compressive directions, and eventually peeling occurs at the interface between the metal and the resin, and moisture infiltrates from the peeled part. This can lead to damage to electronic circuits. However, if a highly filled epoxy resin 15 whose coefficient of thermal expansion is close to that of metal is used, the generated internal stress is small, so peeling does not occur. Generally, when thermal shock resistance is required, flammable resins are sometimes used, but these are not very reliable in terms of moisture resistance. However, this highly filled epoxy resin 15 also has the characteristic of being superior to general thermosetting resins in terms of moisture resistance.

(Effects of the Invention) As described above, in the electronic circuit device according to the present invention, a highly filled epoxy resin to which an inorganic substance is added is used for adhesion between metals using a thermosetting resin. When this highly filled epoxy resin is used, its coefficient of thermal expansion is small and close to that of metals, so it is extremely effective in terms of thermal shock resistance and can provide a sealed structure with extremely high reliability even in harsh environments. It has great corporate value in the field of electronic circuit parts and automotive circuit parts, which will be used in increasingly harsh environments in the future.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of a conventional capacitive pressure sensor, Fig. 2 is an enlarged sectional view of the adhesive part between the metal case and the metal lid, and Fig. 3 is an embodiment of the present invention. Figure 4 is an enlarged cross-sectional view of the adhesive part between the metal case and the metal lid in Figure 4, which shows the results of the sealing degree and reliability of general engineering I xy resin and high-fill type epoxy resin with 40% melt warping force. Characteristic diagram,
FIG. 5 is a basic configuration diagram of the evaluation method. 1... Metal case, 2... Metal lid, 3...
Thermosetting resin adhesive, 4... Solder, 5... Sealing rubber ring, 6... Pressure sensing element portion, 7... Square ring, 8... Holding plate, 9... Glint board, 10...
・Lead wire, 11.14...Rubber, saw, 12...
・Thermosetting resin, 13... Metal wire side, 15... Highly filled resin adhesive, 1a... Recessed part of metal case, 2
a... 7-run part of the metal lid. Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] (1) A metal case having a lead terminal portion that accommodates an electronic circuit, etc. and extracts electrical output, and a metal lid that falls over the opening of the metal case, and the metal case and the lid are bonded together. An electronic circuit device characterized in that a highly filled epoxy resin to which an inorganic substance is added is used as a thermosetting resin adhesive. (2) The electronic circuit device according to claim (1), characterized in that a highly filled epoxy resin to which fused silica is added is used as the adhesive.