JPH03160077A - Adhesive composition for temporarily fixing chip part - Google Patents

Abstract

PURPOSE:To obtain the title composition having sufficient ability to temporarily bond various chip materials by mixing a compound containing ethylenically unsaturated bonds, a monomer containing acidic phosphate groups and unsaturated bonds, a thermal polymerization initiator, an inorganic filler, etc. CONSTITUTION:The title composition having a viscosity at 25 deg.C of 10,000 to 500,000 cP and a structural viscosity index of 3 to 6 is obtained by mixing a compound (A) having polymerizable ethylenically unsaturated bonds, a monomer (B) having at least one acidic phosphate group and at least one unsaturated group, a thermal polymerization initiator (C), an inorganic filler and/or thixotropic agent (D), and it necessary, a photopolymerization initiator (E). Because of the incorporation of component B into component A, this adhesive composition has a sufficient ability to temporarily bond a chip part even to a material to which the adherend of the chip part is hard to bond (e.g. glassy material). Therefore, it can noticeably prevent falling off of chip parts in the soldering process, which has been a problem so far.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an adhesive for temporarily fixing electronic components in a predetermined position before inserting them into a solder bath when fixing electronic components onto a printed circuit board by soldering. Regarding the composition.

[Conventional technology]

In recent years, as electronic devices have become smaller and lighter, the use of small electronic components without lead wires, that is, chip components, is rapidly increasing. Along with this, the demand for adhesives for temporarily fixing chip components to wiring boards is rapidly increasing year by year.

Conventionally, various adhesives have been proposed and tried as adhesives for chip components.

Some of these adhesives include a polymerizable prepolymer reactive diluent, a photoinitiator, and a thermal polymerization initiator. For example, urethane (
meth)acrylate [Here, (meth) refers to both methacrylic acid compounds and acrylic acid compounds.

Same below], Eboxy (meth)acrylate, (Meth)
Adhesives consisting of polymerizable prebolimers such as acrylic acid-modified polyptadiene and photo and thermal polymerization initiators are also used.
JP-A-59-223775 discloses an adhesive comprising an epoxy (meth)acrylate prebolimer, a reactive diluent (aliphatic polyester diacrylate), and a photopolymerization initiator and a thermal polymerization initiator.

[Problem to be Solved by the Invention] However, even if chip components are bonded to a printed circuit board using the above adhesive, this is only temporary bonding, and in order to achieve complete bonding with solder, the chip must be bonded in the temporarily bonded state. The entire printed circuit board must be immersed in a solder bath at a temperature of about 260''C. Moreover, the solder bath is constantly being used in circulation to remove foreign matter and to replenish the solder components that are decreasing due to use and evaporation. Therefore, even though it is a temporary adhesive, it can withstand the high temperature and flow of the solder bath, and after being immersed in the solder bath, it can be taken out and cooled, and the chip components can be temporarily fixed without falling off until the solder bond is almost complete. In the above-mentioned conventional products, the reliability of temporary bonding tends to decrease due to the glass quality of the glass coated surfaces of glass diodes and rectangular resistors, for example.

The inventors of the present invention conducted intensive research to develop an adhesive that has sufficient temporary adhesion properties not only for ordinary chip materials but also for chip parts whose adhesive surface is made of glass material. We have completed a temporary adhesive composition that has excellent temporary adhesion reliability.

[Means for Solving the Problems] The present invention aims to solve the above problems, and includes a compound having a polymerizable ethylenically unsaturated bond (component A),
Contains a monomer having one or more acidic phosphoric acid groups and one or more unsaturated bonds (component B), a thermal polymerization initiator (component C), an inorganic filler and/or a thixotropic agent (component D), and if necessary , containing a photopolymerization initiator (component E), 25°C
This is an adhesive composition for temporarily fixing chip components, which has a viscosity of 10.000 to 500.000 centipoise and a structural viscosity index of 3 to 6.

In the present invention, as the component A, which is a compound having a polymerizable ethylenically unsaturated bond, it is preferable to use unsaturated polyester and/or polyurethane poly(meth)acrylate in order to obtain good adhesive strength.

The unsaturated polyester is made by combining an unsaturated dibasic acid such as maleic acid or fumaric acid, and if necessary, a saturated dibasic acid such as adipic acid or phthalic acid with a polyhydric alcohol such as ethylene glycol, propylene glycol, or bisphenol A. Obtained by esterification in the presence of a catalyst.

Polyurethane poly(meth)acrylate is a urethane poly(meth)acrylate that is obtained by reacting a polyisocyanate compound with a polyfunctional alcohol such as polyester polyol, polyether polyol, polycarbonate polyol, or polybutadiene polyol, and has an active isocyanate group at the end and a hydroxyl group. It can be obtained by a known method such as reacting a containing (meth)acrylate.

As the compound having a polymerizable ethylenically unsaturated bond, in addition to the above, a reactive diluent can also be used in combination, and examples thereof include polyfunctional (meth)acrylates and monofunctional (meth)acrylates.

Examples of polyfunctional (meth)acrylates include 1-limethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tris(acryloxyethyl)isocyanurate, 1,6-hexanediol di(meth)acrylate, Triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalic acid ester neopentyl glycol di(meth)acrylate, ethylene oxide Examples include a (meth)acrylic compound of bisphenol A added with or diglycidyl ester di(meth)acrylate 1 of a dibasic fatty acid having 4 or more carbon atoms.

Examples of monofunctional (meth)acrylates include hydroxyethyl (meth)acrylate, tetrahydrofurfuryl ethyl (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and the like.

The monomer (B component) having at least one acidic phosphoric acid group and one or more unsaturated bonds provides sufficient adhesion at high temperatures even to chip parts whose adhesive surfaces are glassy. For example, (meth)acryloyloxyethyl acid phosphate, (meth)acryloyl polyethylene glycol acid phosphate, (meth)acryloyl polypropylene glycol acid phosphate, 2-hydroxyethyl (meth)acrylate. and ε-cabrolactone adduct phosphate ester, (meth)acryloyloxyethyl acid phosphate hydroxyethylammonium salt, (meth)acryloyloxyethyl acid phosphate phosphate (meth)
Acrylicyloxyethyl-N-dimethylamine salt, (
Examples include (meth)acryloyloxyalkyl and phosphates such as meth)acryloyloxy-3-chloropropyl 2-acid phosphate.

In addition, monomers having one or more acidic phosphoric acid groups and one or more unsaturated bonds (component B) may react during storage to form dimers or sankei bodies, and component A and other monomers may react during storage. Even if they react with other components, the numbers of acidic phosphoric acid groups and unsaturated bonds are calculated based on the monomer before polymerization, regardless of such conditions.

A compound having a polymerizable ethylenically unsaturated bond (At
7. The ratio of the B component to 100 parts by weight of the sum of the compound having at least one acidic phosphoric acid group and one or more unsaturated bonds (component B) is 0.5 to 10% by weight, preferably 1 to 10% by weight.
It is 5 parts by weight.

In the present invention, component C, a thermal polymerization initiator, includes penzoyl peroxide, tert-butyl peroxyallyl carbonate, methyl ethyl ketone peroxide, cyclohexanone peroxide, 1,1-bis(tert-butyl peroxy) 3,3.5 -Trimethylcyclohexane, 1.1-bis(tert-butyl baroxy)cyclohexane, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, tert-butyl baroxy 3.5.5-1 Examples of organic peroxides include -limethylhexanoate, tert-butylbaroxybenzoate, and 2,5-dimethyl-2,5-di(penzoylperoxy)hexane, but penzoylperoxide is a two-component , tertiary butyl peroxybenzoate is suitable for use as a one-component adhesive composition for temporarily fixing chip components.

The amount of the thermal polymerization initiator and component C used is 0.1 to 5 parts by weight, preferably 0.5 to 4 parts by weight, based on 100 parts by weight of the sum of components A and B. If it is less than 0.1 parts by weight, heat curing will be slow, and if it exceeds 5 parts by weight, the storage stability of the &[I parabolite will decrease.

Furthermore, as a curing accelerator, long-chain organic acid metal salts (metallic soaps) such as cobalt naphthenate, cobalt octenoate, manganese naphthenate, and manganese octenoate, dimethylaniline, N-phenylmorpholine, and trimethylbenzylammonium chloride are used. It is also possible to add amines such as or quaternary ammonium salts thereof.

The adhesive for temporarily fixing chip components is the copper foil part (called solder land) left after etching on the printed circuit board.
However, after application, the adhesive may flow over the board and cover the surface of the solder land. In this case, the substrate suffers a serious defect in that solder does not adhere to only the covered portion in subsequent steps.

In the present invention, component D imparts structural viscosity to the adhesive,
This prevents the adhesive from flowing after application and allows the adhesive to have a viscosity suitable for application by methods such as dispenser, pin transfer, or screen printing.

The inorganic filler of component D includes, for example, talc, alumina,
Examples include silica, titanium oxide, aluminum hydroxide, calcium carbonate, and glass powder. Further, thixotropic agents include, for example, fumed silica. When an inorganic filler is used as component D, the amount is 10 to 300 parts by weight, preferably 20 to 150 parts by weight, per 100 parts by weight of the sum of components A and B, and a thixotropic agent is used as component D. In this case, the sum of A component and B component is 100
It can be used in an amount of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight.

By using an inorganic filler or a thixotropic agent within the above range, the coating workability of the composition will be improved, but if it is used beyond the above range, the viscosity of the composition will increase and, conversely, the coating workability will be impaired. This is not preferable because it lowers the temperature. Moreover, an inorganic filler and a thixotropic agent can also be used together.

As the photopolymerization initiator and component E, benzyl and its derivatives, penzophenone and its derivatives, anthraquinone and its derivatives, benzoin, benzoin methyl ether, penzoin edyl ether, penzoin isobrobyl ether, penzoin isobutyl ether, Examples include acetophenone and its derivatives, 2-diethylaminoethylbenzoate, p-dimethylaminoedylbenzoate, diphenyl disulfide, thioxanthene and its derivatives, and one or more of these may be used.

The amount used is preferably 0 to 5 parts by weight per 100 parts by weight of the sum of components A and B, and if more than 5 parts by weight is used, the strength of the cured product may decrease.

Furthermore, in order to improve the storage stability of Mi precepts, polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, 2,2゛-methylenebis(4-methyl-6-tert-butylphenol), and phenothiazine, and for coloring are added. Various dyes and pigments may be added insofar as they do not impair the properties of the composition (photopolymerizability, thermal lightning bonding properties, adhesive strength, etc.).

In order to maintain the above-mentioned preferred physical properties, the adhesive composition of the present invention has a viscosity of 10,000 to 25°C at 25°C.
500,000 centipoise, preferably 20,000
−100,000 centipoise. Further, the structural viscosity index is 3 to 6, preferably 2 to 4.

[Function] In addition to the conventional main component, a compound having a polymerizable ethylenically unsaturated bond, the present invention uses a monomer having at least one acidic phosphoric acid group and one or more unsaturated bonds as component A. By using them together, it is possible to improve the adhesion at high temperatures even to chip parts whose adhesive surfaces are glassy. As a result, it is possible to provide a highly reliable adhesive composition for temporarily fixing chip components that does not fall off even during the harsh operation of immersion in a solder bath. In addition, by maintaining an appropriate structural viscosity index, workability is improved while
To prevent an accident in which the solder land is covered.

〔Example〕

Adhesive compositions were prepared with the formulations shown in Table 1, and the heat strength of each adhesive at 260°C was measured. The hot strength measurements are approximately 0.5 volts for a 1/8 watt cylindrical resistor and a glass diode on an aluminum plate. 6m
g of adhesive to the glass-coated surface of the 2l2 pentagonal resistor. After applying 2 mg of adhesive and placing the chip component on the coated surface, the adhesive was cured for 3 minutes in an open air at 160''C to prepare a test piece. After being immersed in an oil bath for 150 seconds, the heat strength (g) was measured using a push-pull gauge in the oil bath.

In addition, the viscosity can be determined by filling a container with adhesive and lowering the temperature of the adhesive by 2.
After the temperature was raised to 5° C., the temperature was measured using a B-type viscometer at 20 rpm, and the unit was expressed in centipoise. Furthermore, the structural viscosity index was determined by measuring the adhesive viscosity at 2 rpm in the same manner as described above.
It is the value obtained by dividing the viscosity value at 2 rpm by the viscosity value at 2 Orpm.

The above results are also listed in Table 1.

Tests similar to Examples 1 to 3 were conducted using adhesives prepared in the same manner as Examples 1 to 3 with the formulations listed in Table 1, and the results are shown in Table 1. Also listed.

In addition, in Table 1, *l PM2 1 is a phosphate ester in which ε-cabrolactone is added to 2-hydroxyethyl methacrylate *2 JPA514 is methacrylate ethyl acid phosphate *3 JP504 is butyl acid phosphate be.

[Margin below]

[Effects of the Invention] The adhesive of the present invention, which contains a monomer having one or more acidic phosphoric acid groups and one or more unsaturated bonds, can be used even if the adhesive surface of chimps or parts is made of materials that are difficult to adhere to. It is possible to significantly prevent chip components from falling off during the soldering process, which has been a problem.

Claims (3)

[Claims] (1) Component A: A compound having a polymerizable ethylenically unsaturated bond, Component B: A monomer each having one or more acidic phosphoric acid groups and one or more unsaturated bonds, Component C: A thermal polymerization initiator, Component D : Contains an inorganic filler and/or thixotropic agent, if necessary Component E: Contains a photopolymerization initiator, has a viscosity at 25°C of 10,000 to 500,000 centipoise, and a structural viscosity index of 3 to 6. An adhesive composition for temporarily fixing chip components, characterized by the following. (2) The monomer having one or more acidic phosphoric acid groups and one or more unsaturated bonds (component B) is the sum of the compound having a polymerizable ethylenically unsaturated bond (component A) and the component B.
The adhesive composition for temporarily fixing chip components according to claim 1, wherein the adhesive composition is 0.5 to 10 parts by weight. (3) For a total of 100 parts by weight of a compound having a polymerizable ethylenically unsaturated bond (component A) and a monomer having one or more acidic phosphoric acid groups and one or more unsaturated bonds (component B), Thermal polymerization initiator (component C) is 0.1 to 5 parts by weight, and the amount of inorganic filler and/or thixotropic agent (component D) is 0.1 to 5 parts by weight.
5 to 300 parts by weight and 0 to 5 parts of photopolymerization initiator (component E)
The adhesive composition for temporarily fixing chip components according to claim 1 or 2, which is in parts by weight.