JPH0541358B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a flux composition for soldering which contains a specific fluorine-based polymer as an active ingredient and improves uneven application of flux. "Technical background of the invention and its problems" When parts of electronic communication devices are joined by soldering, it is necessary to remove the oxide film on the joint made of iron, nickel, zinc, copper, silver, or alloys thereof, or to add new For the purpose of preventing severe oxidation and lowering the surface tension of molten solder, flux is applied to the joints in advance. Corrosive flux needs to be washed and removed after soldering, and it is not advisable to apply too much.Also, when connecting lead wires to a printed wiring board, the flux may flow from the through hole to the side where electronic components are mounted. It is important to avoid applying more flux than necessary as seepage may adversely affect the functionality of electronic components. On the other hand, if enough flux does not adhere to the joint, the soldering will be incomplete, resulting in defective joints such as blowholes and pin poles, and soldering defects such as bridging. A method that allows for attachment is desired. ``Object of the Invention'' The object of the present invention is to provide a solder flux composition that is less likely to cause uneven application of flux 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 provides 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. The present invention relates to a solder flux composition containing it as an active ingredient. There are several ways to apply flux to the joints to be soldered, such as applying it with a brush or roller,
There are known methods such as immersion coating the joint in a flux solution, spray coating the flux, immersion coating in foamed flux, or transfer coating by peeling off the dried flux coated on a support film. ing. The composition of the present invention can be applied to any of the above methods,
Especially when applying by dipping into foam flux,
Since the flux becomes finer bubbles, the uneven application of flux to the bonded portion is reduced, and poor bonding can be effectively prevented. Furthermore, the flux composition of the present invention can improve the wettability of the joint and the wettability of molten solder, and can ensure reliable soldering by applying a small amount of flux. The main components of solder fluxes are Utsudorosin, gum rosin, tall oil rosin, modified rosin, etc., various activators and organic acids are added to improve solderability, and water, esters, alcohols, ketones,
A liquid substance dissolved in an aromatic hydrocarbon or the like is usually used. Activators include naphthalene hydrochloride, aniline hydrochloride, hydrazine hydrochloride, dimethylcetylammonium bromide, acetamide, urea, aniline, ethylenediamine, cyclohexylamine, etc., and organic acids include stearic acid, succinic acid,
Palmitic acid, oleic acid, glutamic acid, lactic acid, etc. are known. In the case of foam flux,
A water-soluble silane may be mixed in to promote foam disappearance of the applied foam. The fluoropolymer added to such a liquid flux is a homopolymer of an unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms (hereinafter referred to as polymer A) and/or the unsaturated ester. It is a copolymer (hereinafter referred to as polymer B) of a saturated ester and another copolymerizable compound. The polymer A includes not only monomers having the same number of carbon atoms or the same number of fluorine atoms in the polyfluoroalkyl groups, but also polymers having different numbers of polyfluoroalkyl groups. The unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms is not particularly limited, but the following acrylates or methacrylates are preferred, for example. CF ₃ (CF ₂ ) ₄ CH ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₆ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ OCOCH=CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ ) ₂ OCOCH=CH ₂ CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₄ OCOCH=CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N(CH ₃ ) (CH ₂ ) ₂ OCOC(CH ₃ )=CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N(C ₂ H ₅ ) (CH ₂ ) ₂ OCOCH=CH ₂ CF ₃ (CF ₂ ) ₇ CONH(CH ₂ ) ₂ OCOCH=CH ₂ CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH＝CH ₂ CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC (CH ₃ )＝CH ₂ CF ₃ (CF ₂ ) ₈ CONH (CH ₂ ) ₂ OCOC ( _CH3 )= _CH2 H(OF ₂ ) ₁₀ CH ₂ OCOCH=CH ₂ CF ₂ Cl(CF ₃ ) ₁₀ CH ₂ OCOC(CH ₃ )=CH ₂ The compound that can be copolymerized with the unsaturated ester can be selected within a range as long as it does not impede the effects of the present invention. For example, ethylne, vinyl acetate, vinyl chloride, vinyl fluoride, vinylidene halide, sterene, α-methylstyrene, p-methylstyrene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, poly(oxyalkylene) acrylate , poly(oxyalkylene) methacrylate, acrylamide, methacrylamide, diacetone acrylamide, methylolated diacetone acrylamide, N
-methylol acrylamide, vinyl alkyl ether, halogenated alkyl vinyl ether,
Vinyl alkyl ketone, butadiene, isobrene, chlorobrene, glycidyl acrylate, benzyl methacrylate, benzyl acrylate,
Cyclohexyl acrylate, maleic anhydride,
aziridinyl acrylate or methacrylate,
It is possible to copolymerize one or more types of polymerizable compounds that do not contain perfluoroalkyl groups, such as N-vinylcarbazole, as constituent units of the copolymer. The copolymerization ratio of these copolymer components to the unsaturated ester containing a polyfluoroalkyl group is usually 1 to 70% by weight, especially
10-50% by weight is suitable. In addition, in order to obtain polymers A and B in the present invention, the raw material polymerizable compound is dissolved in a suitable organic solvent, and a polymerization initiation source (a peroxide, an azo compound, etc. soluble in the organic solvent used) is added. A method of solution polymerization by the action of ionizing radiation (such as ionizing radiation) can usually be adopted. Suitable solvents for solution polymerization include toluene, ethyl acetate, isopropyl alcohol,
These include 1,1,2-trichloro-1,2,2-trifluoroethane, tetrachlorodifluoroethane, methylchloroform, and the like. Such a polymer is preferably an oligomer type having a number average molecular weight in the range of approximately 1,000 to 50,000 because it is 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 graft type that combines other copolymerizable compounds, and
A structure such as a block type in which an unsaturated ester portion containing a polyfluoroalkyl group and another copolymerizable compound portion are separated may be adopted. Solvents constituting the solder flux composition of the present invention include hydrocarbons such as toluene, cyclohexane, and heptane, tetrachloroethylene, 1,
1,2-trichloro-trifluoroethane, 1,
Halogenated hydrocarbons such as 1,1-trichloroethane and methylene chloride, ketones such as acetone, methyl ethylene ketone and methyl isobutyl ketone, alcohols such as ethanol, isopropanol, n-propanol and benzyl alcohol, ethyl acetate, Examples include esters such as isoamyl acetate, ethers such as ethylene glycol monomethyl ether and tetrahydrofuran, and amides such as dimethylformamide. The blending amount of polymer A and/or B in the flux composition is 0.01
A small amount of ~10% by weight, preferably 0.1~50% by weight is sufficient. When using a mixture of Polymers A and B, it is preferable to use Polymer B as the main component due to its good solubility in flux liquid. preferable. "Example" Synthesis of Fluorinated Polymers 1 Fluorinated polymers () to () were synthesized by reacting the following compositions in an autoclave at 65°C for 10 hours.

[Table] Example 1 The compound shown in the synthesis example was mixed with isopropyl alcohol, a solvent commonly used for fluxes.
The foaming property of a flux solution containing 5.0% was measured. Transfer 30 c.c. of the above solution to a 100 c.c. colorimetric tube (inner diameter 23 mm,
240 mm in height) and vigorously shaken up and down 20 times to measure the foam height. In addition, the time required for the foamed foam to reduce to half liquid was measured.

[Table] 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.

[Table] Foam quality = Flux liquid volume g - Liquid volume turned into foam g / Flux liquid volume g × 100 As these results show, the flux liquid of the present invention has a suitable amount of time to maintain the foam state. , defects such as seepage are less likely to occur. Further, a high bubble density, that is, a fine bubble indicates that the flux liquid has high wettability to the joint to be soldered, and defects such as uneven adhesion are less likely to occur. Next, a comb-shaped electrode shown in JIS Z-3197 was immersed in a solution containing 5.0% isopropyl alcohol of the compound shown in the synthesis example, and then air-dried. Solder the lead wires to both ends of the comb-shaped electrode,
A voltage of 500V was applied to the comb-shaped electrodes, and the resistance was measured at a room temperature of 40°C and humidity of 90%. The results are shown in the table.

[Table] The results show a high insulation resistance value, indicating 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 joined by solder,
Flux and uneven adhesion are significantly reduced. Furthermore, the wettability of the molten solder to the applied and dried flux is improved, and the rate of soldering defects is reduced. like this,
The good wettability of flux and molten solder, that is, the improved wetting speed, allows the flux application process and soldering process during the manufacture of printed wiring boards, etc. to be carried out in a shorter time, contributing to improved productivity. It will also be done.

Claims (1)

[Claims] 1. A homopolymer of an unsaturated ester containing a polyfluoroalkyl group having 4 to 20 carbon atoms and/or a copolymer of another compound copolymerizable with the unsaturated ester as an active ingredient A flux composition for solder comprising: 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.