JPH0475676B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a method of attaching electronic components to a printed circuit board. Structure of conventional examples and their problems Conventionally, chip parts such as chip resistors and chip capacitors are connected to printed circuit boards through a curable resin composition consisting of a compound having an acryloyl group or a methacryloyl group, a photosensitizer, and a thermal polymerization initiator. The capacitors were temporarily fixed to the capacitor and then soldered in.However, there was a problem in which about 0.01% of the multilayer chip capacitors fell off during the soldering process.
Furthermore, recently, electronic components with leads are attached to one side of a printed circuit board, chip components are attached to the other side via the above-mentioned curable resin composition, and after curing, the surface on which the chip components are attached is dip-dipped with solder. Then, the lead wires are cut and solder dip is performed again. When soldering is carried out twice like this, the dropout rate of multilayer chip capacitors is as high as 0.3%.
Inspection and correction after soldering require an extremely large amount of time, which has become a problem. OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems and improves the reliability of soldering. Structure of the invention Chemical formula

Acrylate or methacrylate represented by [Formula] (X is H or CH ₃ ), where R is

[Formula] Compound (A) having a group 0.05 to 5 parts by weight, Chemical formula

Acrylate or methacrylate represented by [Formula] (X is H or CH ₃ ), where R is

[Formula] Contains 100 parts by weight of a compound (B) that does not have a group and contains at least an epoxy acrylate compound, and 0.05 to 5 parts by weight of a photosensitizer (C) or a thermal polymerization initiator (D) This is an electronic component mounting method in which electronic components are bonded to the electronic component mounting area of a printed circuit board via a curable resin composition and soldered after curing. This method significantly reduces the chance of electronic components falling off during soldering, and reduces production costs. performance and reliability can be improved. R is

Acrylates that do not have [formula] include tetraethylene glycol diacrylate,
Tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, bisphenol A epoxy acrylate, phenol novolac epoxy acrylate, cresol novolac epoxy acrylate, the reaction product of polyethylene glycol or polyester and a diisocyanate compound is acrylated. There are urethane acrylates that can be obtained. R is

Methacrylates without [formula] include 2-hydroxyethyl methacrylate, glycidyl methacrylate,
These include ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate. R
but

Examples of acrylates and methacrylates having the formula include mono(2-acryloyloxyethyl) acid phosphate and mono(2-methacryloyloxyethyl) acid phosphate. Chemical formula

Acrylic represented by [formula] R is a rate or methacrylate.

A mixture consisting of one or more types of compounds that do not have [formula]
R per 100 parts by weight

It is desirable to contain a mixture consisting of one or more types of compounds having the formula in the range of 0.05 to 5 parts by weight, and if it is too small, it will not be effective in improving the adhesion with the chip capacitor.
If the amount is too large, the curability will decrease and the adhesive strength of the parts will also decrease. As a photosensitizer, 2-ethylanthraquinone,
Benzyl dimethyl ketal, benzoin isopropyl ether, benzoin isobutyl ether,
1-hydroxycyclohexyl phenyl ketone,
0.1 to 5 parts of 4-isopropyl-2-hydroxy-2-methylpropiophenone, etc. per 100 parts by weight of the acrylate or methacrylate mixture.
It is preferable to use parts by weight; if the amount is less than 0.1 part by weight, the photocuring speed will be slow and complete curing will be difficult. 5
If it exceeds the weight part, the adhesive strength will decrease, which is not preferable. As a thermal polymerization initiator, t-butylperoxybenzoate, t-butylperoxy(2-ethylhexanoate), t-butylperoxyisopropyl carbonate, t-butylperoxylaurate, benzoyl peroxide, 1,1 -bis(obutylperoxy)3,3,5-trimethylcyclohexane, etc. is preferably blended in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the acrylate or methacrylate mixture. If it is less than 0.1 parts by weight, the curability will be poor, and if it is more than 10 parts by weight, the storage stability will be poor. In addition to the above, it is desirable to add an inorganic filler to increase the viscosity and impart thixotropy to reduce stringiness and spreading during application. As an inorganic filler, one or more of talc, silica powder, ultrafine colloidal silica (Aerosil), aluminum hydroxide, calcium carbonate, clay, organic bentonite, etc. is added in an amount of 5 to 200 parts per 100 parts by weight of the acrylate or methacrylate mixture. Can be used within a range of parts by weight. To improve storage stability, common polymerization inhibitors such as parabenzoquinone, hydroquinone, hydroquinone monomethyl ether, catechol, and 2,6-di-t-butyl-4-methylphenol are used in the range of 0.01 to 0.5 parts by weight. can. moreover

Since the compound having the [Formula] group is acidic, it is desirable to mix it with an equivalent amine compound to keep it as neutral as possible. The stronger the acidity, the more likely the copper foil on the printed wiring board will corrode. Furthermore, the amine compound also acts as a polymerization accelerator for acrylic resins, has the effect of reducing polymerization inhibition caused by oxygen, and can improve the surface curability of the resin. Amine compounds include diethanolamine, triethanolamine, N,N-dimethyldodecylamine, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylsulfone, diethylenetriamine and its derivatives, m-phenylenediamine, etc. can be used. Description of Examples Next, examples will be described in detail. Example 1 The curable resin composition of Example 1 shown in Table 1 was applied between the copper foils 3 of a printed circuit board 2 on which a leaded electronic component 1 had been inserted in advance, as shown in FIGS. 1 and 2. An adhesive layer 4 is formed by applying the adhesive using a dispenser, and a multilayer chip capacitor 5 is formed on the adhesive layer 4.
and then lower it to a height of 8 using a high pressure mercury lamp (2KW).
The adhesive 4 was irradiated with ultraviolet rays for 5 seconds from cm, and then passed through a far-infrared heating furnace and heated for 30 seconds at a substrate surface temperature of about 150° C. to harden the parts of the adhesive 4 that were not exposed to the ultraviolet rays. The adhesive strength in the shear direction between the multilayer chip capacitor and the printed circuit board was measured for a part of the printed circuit board after curing, and the results are shown in Table 1. Thirty pieces were measured, and the average value is shown as x and the minimum value as mm. Further, the cured printed circuit board 2 was immersed in a solder bath at 250° C. for 3 seconds to solder the electrode portion 6, lead wire 7, and copper foil 3. Immediately thereafter, the lead wire 7 was cut with a cutter and immersed in a jet soldering bath at 250°C for 3 seconds. The dropout rate of the multilayer chip capacitor after soldering twice was as good as 0.05%. For Examples 2 to 12, curing and soldering were carried out in the same manner as in Example 1, and good results were obtained as shown in Table 1. As a comparative example

Two types of compositions not containing [Formula] were cured and soldered in the same manner as in Example 1. As shown in Table 1, in the comparison between Comparative Example 1 and Example 1,

Compared to those containing [Formula], there is almost no difference in adhesive strength, but the rate of parts falling off after two solderings is 0.4%, about three times as high.
Comparative Example 2 has the lowest value of adhesive strength compared to Example 9.
It was low at 500g, and the dropout rate after soldering was extremely high at 2%.

【table】

【table】 A: Bisphenol A epoxy acrylate B: Cresol novolac epoxy acrylate C: UL-5003 manufactured by Mitsubishi Rayon Co., Ltd. D: Trimethylolpropane triacrylate E: 2-hydroxyethyl methacrylate F: UT-1002 manufactured by Mitsubishi Rayon Co., Ltd. G:

[Formula] Mono(2-methacryloyloxyethyl) acid phosphate H: Mono(2-acryloyloxyethyl) acid phosphate I: Glycidyl methacrylate J: Tetraethylene glycol dimethacrylate K: n+m≒4 L: t-butyl peroxybenzoate M: benzyl dimethyl tital N: t-butyl peroxy (2-ethylhexanoate) O: 2-ethylanthraquinone P: talc Effects of the invention As described above, the present invention Since the invention uses a curable resin composition, it has excellent adhesion to electronic components, and it can greatly reduce the number of electronic components, especially multilayer chip capacitors, falling off during solder immersion, improving the reliability of soldering and inspecting and inspecting dropped components. The time required for corrections can be significantly reduced.

[Brief explanation of drawings]

Figure 1 is a sectional view showing how electronic parts are installed.
FIG. 2 is a plan view of the same. 2... Printed circuit board, 4... Adhesive, 5... Multilayer chip capacitor.

Claims (1)

[Scope of Claims] 1 0.05 to 5 parts by weight of a compound (A) of an acrylate or methacrylate represented by the chemical formula [Formula] (X is H or CH ₃ ) in which R is a [Formula] group; 100 parts by weight of a compound (B), which is a compound in which X is an acrylate or methacrylate represented by H or CH ₃ ) and R does not have a group of [formula], and which contains at least an epoxy acrylate compound, and a photosensitizer (C) Alternatively, the electronic component is bonded to the electronic component mounting area of the printed wiring board via a curable resin composition containing 0.05 to 5 parts by weight of a thermal polymerization initiator (D), and after curing, the electronic component is soldered. Installation method.