JPS6047732B2 - How to coat electronic parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of coating a protective film or the like on the outer periphery of an electronic component such as a resistor, a capacitor, or a semiconductor element.

Conventionally, as a method for coating the outer periphery of electronic components such as resistors, capacitors, and semiconductor elements, protective coatings, etc., have been applied by coating liquid thermosetting resin on the outer periphery of the electronic component body using methods such as dipping, casting, or roll transfer. The above-mentioned electronic component is heated and then heated to melt and harden it on the outer periphery of the electronic component, or the thermosetting resin powder is brought into a fluid state by air flow, etc., and the preheated electronic component is then thermosetted. A method has been used in which the powder is immersed in a fluidized bed of plastic resin powder to adhere to the outer periphery of the electronic component, and then the powder is heated to melt and harden on the outer periphery of the electronic component.

However, in the above-mentioned method, the air built into the electronic component body or air bubbles drawn into the resin when the thermosetting resin is attached may cause damage to the outer periphery of the electronic component when the resin is heated and melted. There is a problem that the resin comes out by breaking through the adhered resin film and causes pinholes in the cured resin layer. Therefore, in order to solve the above-mentioned problems, the following various methods have been adopted.

As an example, in order to prevent the formation of pinholes etc. due to the air contained in the electronic component body, a low viscosity resin is applied to the outer periphery of the electronic component in advance, and then a thermosetting resin is applied. Another example is a method of coating the outer periphery of an electronic component with a thermosetting resin multiple times, and another example is a method of coating a thermosetting resin in which the composition becomes porous after thermosetting. A method is used in which the outer periphery of an electronic component is coated in advance, the resin is cured, and then a low-viscosity resin is impregnated into the porous resin.

In each of the above methods, the coating process becomes complicated because the resin must be applied multiple times at least twice.

In addition, various solvents are used to form low-viscosity resins used for forming the lower layer coating or impregnating porous resins, which may worsen the working environment in factories where electronic parts are manufactured. This may also cause problems in the health management of people. In particular, in the case of electronic components such as cylindrical ceramic capacitors, which have a hollow cylindrical ceramic body as a component, a relatively large amount of air is contained within the electronic component body due to its structure. It cannot be coated by any of the conventional methods.

Although it is possible to use a thermosetting resin to cover electronic components such as the cylindrical ceramic capacitor mentioned above with resin, it is also possible to use a thermosetting resin to cover electronic components such as the cylindrical ceramic capacitor mentioned above. For products that are compatible with each other or products that use lead wires, the above-mentioned photocurable resin has poor adhesion to metal surfaces. The drawback is that moisture and the like can enter through the interface, making it extremely difficult to maintain reliability as an electronic component.

By the way, the present invention solves the above-mentioned problems and ensures that the coating layer is coated on the outer periphery of an electronic component without causing pinholes or the like and is particularly suitable for structures such as cylindrical ceramic capacitors. This makes it possible to coat even electronic parts that contain a large amount of air inside their bodies.

Examples of the present invention will be described below in the order of steps and specific materials used.

1 and 2 show a cylindrical ceramic capacitor, which is an example of an electronic component coated with resin by the method according to the present invention.

Reference numeral 1 denotes a hollow cylindrical ceramic body made of ceramic such as barium titanate, strontium titanate, titanium oxide, etc., and conductive paint, For example, silver (A
g) Paint is applied in a predetermined shape and fired under predetermined conditions to form opposing electrodes consisting of the first and second electrodes 2a and 2b.

That is, the above-mentioned counter electrode is one of the first electrodes 2
a is continuous from the inner circumferential surface 1a of the ceramic body 1 to the outer circumferential surface 1b via one end, and the outer circumferential surface 1 of the ceramic body 1
b, the two electrodes are spaced apart from each other by a sufficient distance so that they do not come into contact with the other second electrode 2b. Then, metal conductive electrode caps 3a and 3b corresponding to the first and second electrodes 2a and 2b formed as described above are press-fitted into both end portions of the ceramic body 1 with an appropriate pressing force. It is fitted.

Note that each of the electrodes 3a and 3b described above is fitted so that a portion of the first and second electrodes 2a and 2b on the outer peripheral surface 1b of the ceramic body 1 is exposed. In addition, each of the electrode caps 3a, 3b and the first and second electrodes 2a, 2b are joined to each other while maintaining airtightness inside the ceramic body 1.
A conductive paint 4 such as a photocurable conductive paint is applied to the partially exposed part, and the conductive paint 4 is cured by irradiation with light, etc., and the electrical and mechanical properties are A physical connection is being made.

Thermosetting resin A blended as shown in Table 1 below and photocurable resin B blended as shown in Table 2 below were applied to the outer periphery of the cylindrical ceramic capacitor formed as described above.
A resin composition obtained by mixing the above is applied by a method such as coating.

Table 1 A: Thermosetting resin Epoxy resin Epicoat 828 (trade name) 9 weighing parts Epoxy resin Epikoat 1001 (trade name) 1 weighing part Touch
5 parts by weight of medium BF3 monoethylamine complex salt
2 Table B: Photocurable resin Polyester-based photocurable resin 1 (4) parts by weight (trade name, [JVR-100 manufactured by Sanyu Resin Co., Ltd.) Supervised contact
Medium diphenyl sulfide: 2 parts by weight Catalyst: 1 part by weight of benzoyl peroxide Next, about 20 parts of the resin composition obtained by mixing the above thermosetting resin A and photocurable resin B were added.
After adhering to a thickness of about 0p by dipping, roll transfer method, etc., the photocurable resin B in the resin composition is first irradiated with about 1 kW to 2 kW ultraviolet lamp. Light cure.

Thereafter, the resin composition is heated at a temperature of about 150'C for about 2 hours to thermoset the thermosetting resin A in the resin composition. In this way, the attached resin composition is applied to the outer periphery of the electronic component.
The coating is applied to electronic components such as the cylindrical ceramic capacitor by curing the coating in stages. By the way, sample No. 1 was obtained by mixing the thermosetting resin A and the photocuring resin B in the proportions shown in Table 3 below. l to NO. The resin compositions up to 5 were applied to the cylindrical ceramic capacitors with lead wires shown in FIGS.
For each sample, five cylindrical ceramic capacitors were heated at 0'C for 20 minutes to form a resin film.
? A rated load life test was conducted under constant temperature and humidity conditions at a temperature of 40° C. and an effective humidity of 95 to 98% RH.

That is, after applying the rated DC voltage of 50V to the capacitor for 500 hours, it was taken out and left at room temperature and humidity for 1 hour, and the capacitor's withstand voltage, capacitance change rate, insulation resistance value, pinhole occurrence, etc. were measured and tested. After confirming the number of defects generated according to the measurement standards, the test results shown in Table 4 below were obtained. That is, sample No. 1 coated with a resin composition containing no thermosetting resin A. 1(4) for l
) After the passage of time, the occurrence of pinholes was observed in one piece, and 25
(g) After the period has passed, the insulation resistance of 7 pieces is 500MΩ.
The result is 3 out of 50 after 5 hits. The insulation resistance became less than 500MΩ.

Sample No. 1 coated with a resin composition containing no photocurable resin A. Regarding 5, after 100I Terama passed, pinholes were observed for 2 years, and at least 25
After 0 hours had elapsed, pinholes were observed in all five cases. In this way, thermosetting resin A and photocuring resin B were used as sample No. in Table 3. 2 to NO. Regarding the coated cylindrical ceramic capacitor obtained by the method of the present invention using the resin composition obtained by mixing the resin composition in the ratio shown in 4, no occurrence of pinholes and no decrease in insulation resistance are observed.
That is, the coating can be applied without producing any defective products.

Further, the thermosetting resin A and the photocuring resin B constituting the resin composition used in the method of the present invention may be as shown in Table 5 below.

Table 5 A: Thermosetting resin phenolic resin Sumilak PC-1 (trade name, manufactured by Sumitomo Juretsu Co., Ltd.) B: Photocurable resin Polyester-based photocurable resin (trade name, UVR-10)
(manufactured by Sanyu Resin Co., Ltd.) 10 parts by weight Catalyst 2 parts by weight of diphenyl sulfide Catalyst 1 part by weight of benzoyl peroxide; No. 1, which is a sample obtained by mixing in the proportions shown in the table. l to N
O. The resin compositions up to No. 5 were applied to the cylindrical ceramic capacitors with lead wires shown in FIGS. 1 and 2 to a thickness of about 200μ in the same manner as described above, and then
The above cylindrical ceramic capacitors were irradiated with a W ultraviolet lamp for W seconds and then heated at a temperature of 150'C for 2 hours to form a resin film. Five pieces of each sample were obtained at a temperature of 40C and an effective humidity. A rated load life test was conducted in a constant temperature and humidity environment of 95 to 98% RH.

That is, after applying the rated DC voltage of 50V to the capacitor for 50 hours, take it out and leave it for one hour at room temperature and humidity. When we checked the number of defects that occurred in accordance with the standards, we obtained test results as shown in Table 6 below.
That is, sample No. 1 coated with a resin composition containing no thermosetting resin A. After 10011 Terama passed, pinholes were observed in 1 piece, and after 25 hours the insulation resistance of 7 pieces was 500 MΩ or less, and after 50 C@, the insulation resistance of 1 out of 50 pieces was 500 MΩ. It became the following. Sample No. 1 coated with a resin composition containing no photocurable resin A. Regarding 5, pinholes were observed in 2 fences after 10 (b) hours had passed, pinholes were found in 48 fences after at least 250 hours, and all 5 fences had been found after 50 (roll) hours had passed. The occurrence of pinholes was observed. In addition, sample No. with a high mixing ratio of thermosetting resin A. About 4 500F1 Terama after 5
Insulation resistance was 500MΩ or less for each piece. Even when phenolic resin is used for such thermosetting resin A, photocurable resin B and sample No. 3 in Table 3
．． 2 and NO. Regarding the coated cylindrical ceramic capacitor obtained by the method of the present invention using the resin composition obtained by mixing the resin composition in the range shown in 3, no occurrence of pinholes or decrease in insulation resistance is observed. In other words, the coating can be applied without producing any defective products.

In each of the above-mentioned embodiments, the results obtained using a cylindrical ceramic capacitor that contains an extremely large amount of air and connects a ceramic body and a metal cap suggest that other electronic components such as resistive elements may not be used. It goes without saying that similar or even better results can be obtained.
As described above, in the method of the present invention, a resin composition obtained by appropriately mixing a thermosetting resin and a photocurable resin is attached to the outer periphery of an electronic component body, and then the resin composition is sequentially photocured. The coating is applied to the electronic component using a stepwise method of heat curing.

Therefore, according to the method of the present invention, the step of applying the resin composition to the electronic component can be completed only once.

A highly reliable coating without the occurrence of pinholes can be achieved simply by photocuring the resin composition and curing it stepwise with heat curing. In addition, since a thermosetting resin is mixed into the resin composition, it is possible to coat electronic parts with good adhesion even on metal bodies such as saw F wires and electrode caps, making it highly reliable. You can get things. Furthermore, it is also possible to coat electronic components such as cylindrical ceramic capacitors that contain a large amount of air inside their bodies. Furthermore, since there is no need to use a so-called solvent-type resin whose viscosity is lowered with a solvent, the working environment will not be degraded. “

[Brief explanation of the drawing]

1 and 2 show a cylindrical ceramic capacitor to which the present invention is applied, with FIG. 1 being a side view thereof and FIG. 2 being a sectional view thereof.

Claims (1)

[Claims] 1. A photocurable resin composition containing a thermosetting epoxy resin or phenol resin in 10 to 40% by weight of the total resin is coated on an electronic component body, photocured, and then thermally cured. Method of coating electronic parts.