JP2520118B2 - Cream solder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cream solder, and more particularly to a cream solder containing 2-ethylhexanol as a solvent and an adduct of ethylene oxide and / or propylene oxide or both components thereof.

Conventional technology Cream solder is a flux obtained by dissolving and dispersing a resin, an activator, a viscoelasticity adjusting agent, an additive, etc. in a solvent, and solder powder is dispersed in a cream form. Heat fusion is performed.

As a solvent for cream solder, xylene, terpineol, hexylene glycol, etc. have been used for a long time because they have a good dissolution property for natural rosin and rosin monomer and provide a stable solution. However, since the drying speed is very fast, workability after application is poor, solder balls and residues are likely to be generated by air oxidation, and the solubility to the activator is poor, resulting in variations in solderability and corrosion. There were drawbacks such as.

After that, along with the practical use of synthetic rosins with good solution stability, solvents such as diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diisobutyl adipate, DOP, etc. or non-drying liquid sticky substances such as polybutene will be used. As a result, cream solder having relatively excellent characteristics has been obtained.

However, since diethylene glycol monobutyl ether has a high hygroscopicity, the viscosity change of the cream solder is large, ethylene glycol monophenyl ether has a peculiar odor, and esters such as diisobutyl adipate and DOP have a low hydrophilicity, so they can be used as an activator. There are problems such as poor compatibility, and liquid adhesive substances such as polybutenes have poor compatibility with rosin-based resins and activators, so that the amount to be blended is limited.

Problems to be Solved by the Invention In view of such circumstances, the present inventor has various characteristics required for cream solder, that is, viscosity does not change, solder balls and residues are less likely to occur, and there is no peeling or drying. As a result of intensive studies to provide a cream solder having characteristics such as good workability, good solderability, and little bad odor or toxicity, either 2-ethylhexanol and ethylene oxide or propylene oxide or its The present invention has been completed by finding out that this problem can be solved by using an adduct with both components as a solvent.

Means for Solving the Problems The present invention relates to a cream solder containing an adduct of 2-ethylhexanol with ethylene oxide and / or propylene oxide.

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

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

Generally, an adduct of 2-ethylhexanol and propylene oxide has a lower boiling point than that of an adduct of 2-ethylhexanol and ethylene oxide, but has low hygroscopicity, is stable, has a weak odor, and has low toxicity. However, by adding both propylene oxide and ethylene oxide to 2-ethylhexanol by appropriately changing the addition ratio and the addition order, it is possible to appropriately adjust the hydrophilicity and the boiling point. it can.

Since such an adduct of 2-ethylhexanol and alkylene oxide has active hydrogen, it is also a good solvent for the activator, so that it can be stably contained to ensure uniform solderability and to protect the solder. Effectively prevent corrosion of the joining metal.

Further, since such an adduct has an ethyl group as a side chain in an alkyl main chain having a relatively large number of carbon atoms, it has extremely good dissolution stability of a resin such as rosin and has not only a small change in viscosity but also a rapid change in viscosity. Since evaporative drying does not occur, problems such as generation of solder balls due to drying and insufficient adhesion of bonded parts do not occur, and the amount of water mixed in from the atmosphere is very small, resulting in moisture absorption by leaving it after printing. Very few solder balls are generated.

If desired, the solvent for cream solder may be appropriately mixed with a solvent that has been conventionally used within a range that does not impair the various properties required for the cream solder.

The cream solder according to the present invention contains the conventional compounding ingredients in the above-mentioned solvent, namely, powdered solder, rosin or rosin derivative, activator and optionally thermoplastic resins, oils and fats (including fatty acids), antioxidants (for example, BHT), thickener, defoaming agent, matting agent, etc.

The powdered solder is 70 to 92% by weight of the total cream solder, and the rest is solvent and other additives, that is, flux.

As liquid flux, rosin or rosin derivative 30
-80 parts by weight, 10-0 parts by weight of activator, 25-6 parts by weight of thermoplastic resin and fats and oils, 20-70 parts by weight of solvent as basic components, and other additives may be appropriately mixed. Viscosity is 8000
About 0 to 600,000 is preferable.

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

Examples of the activator include hydrogen halide salts of nitrogen-containing bases, organic acid salts, organic acids, amino acids and the like. Examples of the nitrogen-containing base include ammonia, primary, secondary and tertiary amines, aromatic amines, heterocyclic amines, guanidines, ureas, amides, alkanolamines and polyamines. Examples of hydrogen halides include HCl, HBr, HF and the like. Examples of the organic acid include acetic acid, lactic acid, phthalic acid, maleic acid, fumaric acid, adipic acid, and examples of the amino acid include glycine, alanine, aspartic acid and glutamic acid.

The thermoplastic resin adjusts the viscosity of the flux, or improves the viscosity, elasticity, composition, etc. to improve the coating properties of the flux. Generally, the thermoplastic resin and fats and oils are used. Suitable thermoplastic resins in the present invention are synthetic waxes, maleic acid resins, polystyrene, modified alkyd resins, ester gums, polybutyral, polyamides, etc., but the above-mentioned maleated rosin, rosin modified phenol formalin polycondensate, rosin itself. May be used as a viscosity modifier. In this case, it is not necessary to add a special component as a viscosity modifier, and this is also included in the technical scope of the present invention. As the viscosity modifier, shellac, drying oil, partially esterified phenol resin or the like may be used.

Such a resin is added so as to obtain a desired viscoelastic property according to the coating method used. In this respect, the technique used in the conventional soldering can be used.

 Hereinafter, the present invention will be described with reference to examples.

Examples 1 to 5 Flux 12 wt% prepared by the formulation of Table-1
And 88% by weight of powdered solder (viscosity 325 mesh) were sufficiently kneaded to prepare cream solders A to E.

The following characteristics were investigated for the obtained cream solders A to E, and the results are shown in Table-2.

(1) Solubility of activator: Solubility of activator at the time of blending flux (“◯”: good, “x”: poor).

(2) Residue immediately after application: degree of residue when reflow is immediately performed after application ("○": excellent, "△": acceptable,
“X”: defective).

(3) Residue after aging: Degree of residue after reflow 12 hours after application (“×”: excellent, “△”:
Yes, "x": bad).

(4) Solderability: Solderability to an oxidized copper plate (“◯”: excellent, “Δ”: acceptable, “x”: not acceptable).

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

(6) Adhesiveness: The degree of fixing force when the parts to be joined are attached immediately after application (“◯”: excellent, “Δ”: acceptable, “x”: not acceptable).

(7) Peelability: The degree of peeling after 12 hours from application (“◯”: excellent, “Δ”: acceptable, “x”: not acceptable).

(8) Dissolution stability of resin: The dissolved and dispersed 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 the flux prepared according to the formulation of Table-1.

With respect to the obtained cream solders a to h, characteristics such as solubility of the activator were examined in the same manner as in Example 1.

 The results are shown in Table-2.

Effect of the Invention The cream solder according to the present invention is an adduct obtained by adding either or both components of ethylene oxide and propylene oxide to 2-ethylhexyl alcohol which is easily available as a raw material of a plasticizer with high purity and low cost. As a solvent, the viscosity does not change over time, there are few solder balls and residues, there is no peeling or drying, workability is good, solderability is good, there is little bad smell or toxicity, etc. , Also has various characteristics required for cream solder.

Claims (3)

(57) [Claims] 1. A cream solder containing an adduct of 2-ethylhexanol and either or both of ethylene oxide and propylene oxide. 2. An ethylene oxide and / or propylene oxide first or both components having an addition mole number of 1 to 4.
Item cream solder. 3. The cream solder according to claim 1, wherein the adduct is an adduct of 2-ethylhexanol and propylene oxide.