JPS6186092A - Flux composition for solder - Google Patents

Abstract

PURPOSE:To improve wettability and to decrease the uneven sticking of a flux by contg. a homopolymer of specific unsatd. ester and/or a copolymer of the unsatd. ester and other copolymerizable compd. as an effective component. CONSTITUTION:The flux compsn. contains the homopolymer of the unsatd. ester contg. a polyfluoroalkyl group of 4-20 C and/or the copolymer of the unsatd. ester and the other copolymerizable copolymer as the effective component. Then the uneven sticking of the flux to the point part hardly arises even in a small quantity of flux coating and the wettability with the molten solder is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a solder flux composition that contains a specific fluoropolymer as an active ingredient and that improves uneven flux application.

"Technical background of the invention and its problems" When joining parts of electronic communication equipment by soldering, iron 1
, nickel, zinc, copper, silver, or their alloys, etc., or to prevent new oxidation, or to lower the surface tension of molten solder, apply flux to the joints in advance. Coating is being done. With corrosive flux, it is necessary to wash and remove it after soldering, and it is not advisable to apply too much. Also, when joining lead wires to a printed wiring board, the flux may leak from the through holes to the mounting area of electronic components. It is important to avoid applying more flux than necessary, as it may have a negative effect on the electronic component function. on the other hand,
If enough flux does not adhere to the joint, the soldering will be incomplete, resulting in poor joints such as blowholes and pinholes, and poor soldering such as bridges. A method that allows for attachment is desired. - "Objective of the Invention" The object of the present invention is to provide a soldering flux composition that is less likely to cause uneven flux application at joints even when a small amount of flux is applied, and that also has improved wettability with molten solder. That's true.

"Structure of the Invention" The present invention relates to a homopolymer of an unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms and/or a copolymer of the unsaturated ester with another copolymerizable compound. The present invention relates to a solder flux composition containing as an active ingredient.

Methods for applying flux to the joints to be soldered include applying with a brush or roller, dipping the joint in a slack solution, spraying flux, and applying flux in foamed slack. Soak in f! ! There are known methods in which the flux is coated on a support film, or the flux that has been coated and dried is peeled off and transferred and coated. The composition of the present invention can be applied in any of the above methods, especially when applied by dipping into foamed flux.
Since the flux becomes finer bubbles, the uneven application of flux to the joints is reduced, and joint defects can be effectively prevented. In addition, the flux composition of the present invention can improve the wettability of the joint and the wettability of molten solder, and can improve the wettability of molten solder.
Reliable soldering is possible by thick coating.

The main components of soldering flux are wood rosin, gum rosin, tall oil rosin, modified rosin, etc., and various activators and organic acids are added to improve soldering properties, and soldering properties are improved using water, esters, and alcohol.

Liquid substances dissolved in ketones, aromatic hydrocarbons, etc. are usually used. Activators include naphthalene hydrochloride, aniline hydrochloride, hydrazine hydrochloride, dimethylcetylammonium bromide,
acetamide, urea, aniline, ethylenediamine,
Cyclohexylamine and the like are known, and examples of organic acids include stearic acid, succinic acid, pernicious acid, oleic acid, glutamic acid, and lactic acid. In the case of foam slacks, water-soluble 7 run may be mixed in to promote the disappearance of the applied foam. The fluoropolymer added to such a liquid flux is an unsaturated ester homopolymer containing a polyfluoroalkyl group having 4 to 20 carbon atoms (
(hereinafter referred to as polymer B) and/or a copolymer of the unsaturated ester with another copolymerizable compound (hereinafter referred to as polymer B)
). The polymers include not only those having the same number of carbon atoms or the same number of fluorine atoms in the polyfluoroalkyl groups in the heptamers, but also those having different numbers of carbon atoms or fluorine atoms.

The unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms is not particularly limited, but for example, the following acrylates or methacrylates are preferred.

C force (OFF), 0HaOOOO(OHi)-CI
'hOFI (OFri, (OHM), OcOO(O
Hm)mCH*(!Fm((Jz) 0OOOH-OH
x・OFI (OFt), 0HxOHzOCOCH=OH
z(!Fl (OFF), OHx CHCHxOO
OCH-OHzH QFs (OFI)y 80N (CsHt) (C force)
, ococa horse mackerel 0Ht (JFs (O1'z )y
(cut)4 QC! 0OH=CHzays (
C! I'riy SOgN (CHI) (CHri, O
COO(CiHs)-CHg(!Fs (C!7g),
SOgN(C!zHs) (CHI)! OCOOH-
OFIgCFs (OFF), C! 01iH(OHx
), 0COCH-OTi2CIPs (cyz)a
(cab), 0OOOH-CHIOFI (CFff
i) @ (OHM)! QC! 00(CHm)-0HzC
Fa (OFF), (!0NE(OHs), 0000(
OHs)-CHgFi(CIPx)lo CHxOCO
CFl-OHzCF*C1((!Ft)xoOHtoo
oo (OHs) = ('HzHCFz (OFz),
CHI 0HCHzOCOOH-(3H! The compound that can be copolymerized with the unsaturated ester can be selected from a wide range as long as it does not impede the effects of the present invention. For example, ethylene.

Vinyl acetate, vinyl chloride, vinyl fluoride, vinylitine halides, styrene, α-methylstyrene, p-methylstyrene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, poly(oxyalkylene) acrylate, poly(oxyalkylene) acrylate alkylene) methacrylate, acrylamide, methacrylamide, diacetone acrylamide, methylolated diacetone acrylamide, N-methylol acrylamide, vinyl alkyl ether, ha) t' 7 -furkyl vinyl ether, vinyl alkyl ketone.

Butadiene, isoprene, chloroprene, glycidyl acrylate, benzyl methacrylate.

benzyl acrylate, cyclohexyl acrylate,
It is possible to copolymerize one or more polymerizable compounds that do not contain perfluoroalkyl groups, such as maleic anhydride, aziridinyl acrylate or methacrylate, and N-vinylcarbazole, as constituent units of the copolymer. be. The copolymerization ratio of these copolymerization components to the unsaturated ester containing a polyfluoroalkyl group is generally 1 to 70% by weight, particularly 10 to 50% by weight.

In addition, in order to obtain polymerizable compounds and B in the present invention, the raw material polymerizable compound is dissolved in a suitable organic solvent, and a polymerization initiation source (peroxide, azo compound, or ionizing radiation soluble in the organic solvent used) is dissolved in a suitable organic solvent. etc.), a solution polymerization method can usually be adopted. Suitable solvents for solution polymerization include toluene, ethyl acetate, isopropyl alcohol, 1,1,2-trichloro-1,2,2-)lifluoroethane, tetrachlorodifluoroethane, methylchloroform, and the like. Such a polymer has a number average molecular weight of about 1,000 to so, oo.

Oligomer types falling within this range are preferred because they are easily soluble in the flux liquid. In addition, the structure of polymer B is a random type in which an unsaturated ester containing a polyfluoroalkyl group and another copolymerizable compound are randomly arranged, and a graft type in which unsaturated esters containing a polyfluoroalkyl group are grouped together. A structure such as a graft type in which one other copolymerizable compound is included, or a block type in which an unsaturated ester part containing a polyfluoroalkyl group and another copolymerizable compound part are separated may be adopted.

Solvents constituting the solder flux composition of the present invention include hydrocarbons such as toluene, cyclohexane, and heptane, and tetrachlorethylene.

1, 1.2-) Lichlorotri7/I/oloethane.

1, 1.1-) Halogenated hydrocarbons such as dichloroethane and methylene chloride, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, alcohols such as ethanol, isoptapanol, n-globanol, and benzyl alcohol, acetic acid Esters such as ethyl and isoamyl acetate, ethylene glycol monomethyl ether.

Examples include ethers such as tetrahydrofuran and amides such as dimethylformamide. The blending amount of polymer A and/or B in the flux composition is 0. O1~
Takashi weight %, preferably 0. A small amount of 1 - 1 weight may be sufficient, and when polymers A and B are used in combination, it is preferable to use polymer B as the main component because of its good solubility in flux liquid.

"Example" Synthesis of Fluoropolymers Fluoropolymers (1) to (F/) were synthesized by reacting the following compositions at 65° C. for 10 hours in a 1° autoclave.

isopropyl alcohol, a solvent used in The foaming properties of the flux solution dissolved in Tai'A were measured.

Add 30 cc of the above solution to a 100 cc colorimetric tube (inner diameter 23 m).
, height 2401111), was shaken vigorously up and down 20 times, and the foam height was measured. In addition, the time required for the foamed foam to reduce to half liquid was measured.

Furthermore, the foam quality of the foamed foam was calculated using the following formula. The smaller the number, the higher the foam density and the finer the foam.

As these results show, the flux liquid of the present invention maintains its foam state for a suitable amount of time, and defects such as seepage are less likely to occur. In addition, high bubble density, that is, fine bubbles, indicates that the flux liquid has high wettability to the joints to be soldered, which may cause defects such as uneven bonding and cause J3;f% dissolution in Lucoll. J Engineering S Z
-3197 was immersed in the comb-shaped electrode and then air-dried.

Lead wires were soldered to both ends of the comb-shaped electrode, a voltage of 500 V was applied to the comb-shaped electrode, and the resistance was measured at a room temperature of 40° C. and a humidity of 90° C. The results are shown in the table.

As a result, it shows a high insulation resistance value, and it can be seen that there is no adverse effect on electrical insulation.

"Effects of the Invention" The solder flux composition of the present invention has good wettability to metals to be welded with solder, and the unevenness of flux application is significantly reduced.

Furthermore, the wettability of the molten solder to the applied and dried flux is improved, and the defective rate of soldering is reduced. Due to the good wettability of flux and molten solder, that is, the wetting speed is improved, the flux application process and soldering process during the manufacture of printed wiring boards etc. can be carried out in a shorter time, and the production It also contributes to improving sexual performance.

Claims (2)

[Claims] (1) Contains as an active ingredient a homopolymer of an unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms and/or a copolymer of the unsaturated ester and another copolymerizable compound. A flux composition for soldering characterized by: (2) The solder flux composition according to claim 1, wherein the unsaturated ester containing a polyfluoroalkyl group is an acrylate or methacrylate containing a terminal perfluoroalkyl group.