JPS63144891A - Cream solder - Google Patents

Abstract

PURPOSE:To obtain cream solder which obviates a change of viscosity, skinning and drying and has good workability by compounding an addition product of 2-ethyhexanol and ethylene oxide an/or propylene oxide as a solvent to the cream solder. CONSTITUTION:The addition product of the 2-ethyhexanol and ethylene oxide an/or propylene oxide is compounded as the solvent with the cream solder. The molar number of the ethylene oxide an/or propylene oxide to be added is preferably set at 1-4. The prepn. of the cream solder is executed by adequately compounding powder solder, rosin, etc., as a flux, activator, etc., with the above-mentioned solvent. The cream solder having such cream characteristics as freedom from the change of viscosity, good workability and good solderability in combination is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cream solder, particularly a cream solder containing an adduct of 2-ethylhexanol and ethylene oxide and/or propylene oxide as a solvent.

Conventional technology Cream solder is a flux obtained by dissolving and dispersing resin, activator, viscoelasticity modifier, additives, etc. in a solvent, and solder powder is dispersed in a cream form. Heat fused.

As a solvent for cream solder, quinolene, terpineol, hequinlene glycol, etc. have been used for a long time because they have good dissolution characteristics for natural rosin and rosin monomer, and provide a stable solution. However, the drying speed is very fast, resulting in poor workability after application, the tendency to form solder balls and residue due to air oxidation, and the poor solubility of activators, resulting in uneven solderability and corrosion. It had drawbacks such as being easy to use.

Subsequently, with the practical use of synthetic rosins with good solution stability, solvents such as diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, noisobutyl adipate, and DOP, or non-drying liquid sticky substances such as polybutenes were used. As a result, cream solder with relatively robust properties has become available. However, diethylene glycol monobutyl ether has high hygroscopicity, which causes a large change in the viscosity of cream solder, ethylene glycol monophenyl ether has a peculiar odor, and esters such as diisobutyl adipate and DOP have low hydrophilicity, so they cannot be used as activators. There are problems such as poor compatibility with rosin resins and activators, and liquid adhesive substances such as polybutenes have poor compatibility with rosin resins and activators, so there is a limit to the amount they can be blended.

Problems to be Solved by the Invention In view of the above circumstances, the present inventor has developed a technology that meets the various characteristics required of cream solder, namely, no change in viscosity, little generation of solder balls and residue, and no drying of the skin. As a result of extensive research in order to provide a cream solder with properties such as good workability, good solderability, and low odor and toxicity, we found that the addition of 2-ethylhexanol and ethylene oxide and/or propylene oxide The present invention was completed by discovering that this problem could be solved by using a substance as a solvent.

SUMMARY OF THE INVENTION The present invention relates to a cream solder containing an adduct of 2-ethylhexanol and ethylene oxide and/or propylene oxide.

The adduct used in the present invention can be easily prepared by adding ethylene oxide and/or propylene oxide to 2-ethylhexanol by a conventional method.

The number of moles of ethylene oxide and/or propylene oxide added is usually 1 to 4, preferably 1 to 2, and when it is 5 or more, the solubility of the active agent decreases.

Generally, the adduct of 2-ethylhexanol and propylene oxide has a lower boiling point than the adduct of 2-ethylhexanol and ethylene oxide, but it is less hygroscopic and stable.
Although it is preferable because it has a weak odor and low toxicity, it is possible to improve hydrophilicity and boiling point by adding both propylene oxide and ethylene oxide to 2-ethylhexanol by appropriately changing the addition ratio and order of addition. etc. can be adjusted appropriately.

Since such an adduct of 2-ethylhexanol and alkylene oxide has active hydrogen, it becomes a good solvent for the activator, so it is possible to stably contain it to ensure uniform solderability and to reduce the amount of soldering. Effectively prevents corrosion of joining metals.

Furthermore, such adducts have an ethyl group as a side chain on the alkyl main chain with a relatively large number of carbon atoms, so they have extremely good dissolution stability for resins such as rosin, and not only have little viscosity change but also rapid dissolution. Since evaporation drying does not occur, problems such as the formation of solder balls due to drying and insufficient adhesion of parts to be bonded do not occur, and since the amount of moisture mixed in from the atmosphere is extremely small, it is possible to prevent problems such as the formation of solder balls due to drying or insufficient adhesion of parts to be joined. The occurrence of solder balls is extremely rare.

The above-mentioned cream solder solvent may optionally contain conventionally used solvents as long as they do not impede the properties required of the above-mentioned cream solder.

The cream solder according to the invention contains the conventional ingredients in the above-mentioned solvent, namely powdered solder, rosin or rosin derivatives, activators and optionally thermoplastic resins, oils and fats (including fatty acids), antioxidants ( For example, BHT), a thickener, an antifoaming agent, a matting agent, etc. are appropriately blended.

Powdered solder makes up 70 to 92% by weight of the total cream solder, with the remainder being solvent and other additives, ie, flux.

Rosin or rosin derivative 30 as liquid flux
The basic components are ~80 parts by weight, 10-0 parts by weight of an activator, 25-6 parts by weight of thermoplastic resin and fats and oils, and 20-70 parts by weight of a solvent, and other additives may be blended as appropriate. The viscosity is preferably about 5oooo to 6ooooo.

The rosin or rosin derivative used in the present invention may be those conventionally used for fluxes, such as rosin, disproportionated rosin, hydrogenated rosin, maleated rosin, and polymerized rosin.

Examples of the activator include hydrogen halides of nitrogen-containing bases, organic acid salts, organic acids, and amino acids. Examples of nitrogen-containing bases include ammonia, primary, secondary, and tertiary amines, aromatic amines, heterocyclic amines, guanidine, urea, amides, alkanolamines, and polyamines. Hydrogen halides include HC&.

1-IBr, HF, etc. Organic acids include acetic acid, lactic acid, phthalic acid, maleic acid, fumaric acid, adipic acid,
Examples of amino acids include glycine, alanine, aspartic acid, and glutamic acid.

The thermoplastic resin adjusts the viscosity of the flux or improves the viscosity, elasticity, composition, etc., and improves the application characteristics of the flux, and generally thermoplastic resins and oils are used. Suitable thermoplastic resins in the present invention include synthetic waxes, maleic acid resins, polystyrene, modified alkyd resins, ester gums, polybutyral, polyamides, etc., including the aforementioned maleated rosin, rosin-modified phenol-formalin polycondensate, and rosin itself. may be used as a viscosity modifier. In this case, there is no need to add a special component as a viscosity modifier, and this is also within the technical scope of the present invention. Shellac as a viscosity modifier,
Drying oils, partially esterified Fair'all resins, etc. may also be used.

Such resins are added so as to obtain desired viscoelastic properties depending on the coating method used. In this regard, techniques used in conventional soldering can be utilized.

Hereinafter, the present invention will be explained by examples.

Example 1 12% by weight of flux prepared according to the formulation shown in Table 1
Cream solder A was prepared by sufficiently kneading the powdered solder (particle size: 325 mesh) and 88% by weight M%.

The following characteristics of the obtained cream solder A were investigated,
The results are shown in Table-2.

(1) Solubility of activator: Solubility of activator when blending flux ("○": good, "×": poor).

(2) Residue immediately after application - Level of residue when reflowing immediately after application (rOJ: f2, "△": OK,
"X": defective).

(3) Residue after time: degree of residue when reflow was performed 12 hours after application (rXj: excellent, "△": fair, "×": poor).

(4) Solderability Solderability to carbon dioxide treated copper plate (
"○": Excellent, "△": Acceptable, "×": Not acceptable).

(5) Odor: Degree of odor generated during reflow (“O”:
Odorless, "△" odor, "x": unpleasant odor).

(6) Adhesiveness: degree of adhesion when parts to be joined are attached immediately after application ("○": f9, "△": acceptable, "×": not possible).

(7) Skin elasticity: degree of skin elasticity 12 hours after application ("○": excellent, "△": fair, "x": poor).

(8) Dissolution stability of the resin Dissolution and dispersion state of the resin 100 days after preparation ("○": stable, "x": unstable).

Comparative Examples 1 to 8 Cream solders a to h were prepared in the same manner as in Example 1 using fluxes prepared according to the formulations shown in Table 1.

The properties of the obtained cream solder a=h, such as the solubility of the active agent, were investigated in the same manner as in Example 1.

The results are shown in Table-2.

Effects of the Invention The cream solder according to the present invention uses, as a solvent, an adduct obtained by adding ethylene oxide and/or propylene oxide to 2-ethylhexyl alcohol, which is easily available at high purity and low cost as a raw material for a plasticizer. It is characterized by the fact that the viscosity does not change over time, there is little generation of solder balls and residue, and the skin does not dry out, making it easy to work.
It has all the properties required of cream solder, such as good solderability, low odor and toxicity.

Claims (1)

[Claims] A cream solder containing an adduct of 1,2-ethylhexanol and ethylene oxide and/or propylene oxide. 2. The cream solder according to item 1, wherein the number of moles of ethylene oxide and/or propylene oxide added is 1 to 4. 3. The cream solder according to item 1, wherein the adduct is an adduct of 2-ethylhexanol and propylene oxide.