JPH03106594A - Flux composition for soldering - Google Patents

Abstract

PURPOSE:To provide the flux compsn. for soldering which has good solderability and has no corrosiveness by adding alcohol halide as an activator to the flux compsn. consisting of a rosin resin, etc., and a solvent. CONSTITUTION:One or more kinds of the rosin resin, high boiling vehicle, etc., are incorporated as essential components into the flux compsn. for soldering. The flux compsn. is constituted of this compsn. and a solvent. The alcohol halide is added as the activator to this flux compsn. A hydrocarbon halide which has double bonds between the carbon atoms in the molecule and is combined with a halogen element directly to the carbon atoms is added as the activator to the flux. The flux compsn. for soldering which has excellent electrical characteristics and does not require washing is provided in this way.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to the improvement of soldering flux, and by adding an organic halogen compound having a specific chemical structure as a component of various soldering fluxes, high reliability such as corrosion resistance and electrical properties can be achieved. The present invention aims to provide an improved flux composition for soldering which has a high soldering reliability PI and can also meet the demand for no-cleaning.

[Conventional technology and its problems]

When soldering a printed wiring board equipped with a large number of electronic components, conventionally, for example, rosin-based fluxes are generally based on rosin-based resin dissolved in an organic solvent, and a It is made up of additives with ionic substances, such as hydrohalides of organic amines and organic acids. Furthermore, as a special example, it has been proposed that a halogen compound having a specific structure as shown in JP-A-54-81146 be used as an activator, but this compound also has an ionic name. are doing. However, printed wiring boards soldered with such ionic flux must be treated with halogenated hydrocarbon-based cleaning agents such as chlorofluorocarbons and trichloroethane to prevent corrosion and ensure high reliability. Cleaning is required. However, in recent years, a policy of not using fluorocarbons has been adopted on a financial scale, as it causes the destruction of ozone dust.
There are concerns about trichloroethane's impact on groundwater, so the use of trichloroethane is also being regulated.

[Problem to be solved by the invention]

In view of the above-mentioned circumstances, the present invention aims to provide a soldering flux composition that has good solderability, is non-corrosive, has excellent electrical properties, and does not require cleaning. . The present inventor has made a systematic study of the relationship between the chemical structure of the activator, which is one of the flux components, and its activation power, corrosivity, and electric characteristic PH. We have discovered that G-type halogen compounds belonging to three groups, which have not been considered as active FF agents for flux, are particularly excellent in achieving the above objectives, and have completed the present invention. .

[Structure of the invention]

The present invention consists of base components such as rosin resins, high boiling point solvents, organic acids, polyhydric alcohols and derivatives thereof, which are generally used in flux compositions, as well as activators, solvents, and additives. In the soldering flux composition, firstly, halogenated alcohol,
Second, halogenated hydrocarbons have double bonds between carbon atoms in the molecule and a halogen element is directly bonded to the carbon atoms, and third, halogenated aliphatic carboxylic acid esters are used. This is a characteristic feature. Hereinafter f1 the above first, second and third compounds collectively,
These are called specified ￥f machine halogen compounds. As the halogen element mentioned above, bromine and chlorine are industrially suitable. The characteristics of the specific organic halogen compounds in the present invention are as follows:
Since the halogen element forms a so-called covalent bond with carbon, the halogen does not have ionicity and does not contain any ionic groups other than halogen.
Because of the above-mentioned characteristics, a flux composition using such a compound as an activator has a high aqueous resistance value, as will be described later, and can meet the demand for no-cleaning. Next, specific examples of specific organic halogen compounds used in the present invention will be given. First, as the halogenated alcohol, l-bromo 2
-butanol, i-bromo-2-propanol, 3-bromo-l-propanol, 3-bromo-l. 2-propanediol, 1.4 dibromo-2-butanol, tablet. 3
-dibromo2-propanol, 2,3-dibromo-1
-propanol, 1,4-dibromo-2,3-butanediol, 2,3-dibromo-2-butene-1,4-diol, etc. Second, 6 double bonds are formed between carbon atoms in the molecule, and Examples of halogenated hydrocarbons in which a halogen element is directly bonded to a carbon atom include I-bromo-3-methyl-l-butene and 1,4 dibutene.

[
1mopten, I-bromo-l-bropene, 2.3-dipromobropene, etc. Thirdly, halogenated aliphatic carboxylic acid esters include bromoacetic acid ethyl ester, α-bromo n-monocaprylic acid ethyl ester, α-bromobropionic acid. Ethyl ester, β-promopropionate edyl ester, α-
These include promo n-monobutyric acid ethyl ester, α-bromobutyric acid ethyl ester, and the like. Next, in the present invention, substances that are the main components of the composition will be explained. First, rosin-based resins include natural rosin, polymerized rosin, disproportionated rosin, maleic acid-modified rosin, hydrogenated rosin,
Rosin-based resins commonly used in soldering fluxes, such as phenol-modified palm gin and rosin polyhydric alcohol ester, are used. It is desirable to use these rosin resins that have been purified as much as possible by means such as evaporation. High boiling point vehicles include polyethylene glycol,
High boiling point vehicles commonly used in soldering fluxes, such as polypropylene glycol and dioctyl phthalate, can be used. {F Organic acid components include lactic acid, malonic acid, citric acid,
An organic acid component that is generally used for soldering is used, which is based on glycolic acid or the like and uses polyhydric alcohols such as glycerin, propylene glycol, and sorbitol, and their esters as vehicles. Furthermore, the solvent used is water or organic solvents such as methyl alcohol, ethyl alcohol, isobrobyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and butyl carbitol, which are commonly used in soldering fluxes. Among these, isopropyl alcohol (hereinafter referred to as IPA) is suitable. The improved flux composition of the present invention is prepared by mixing the above-mentioned main components, specific organic halogen compounds as an external active agent, and known additives such as a matting agent, which may be added as necessary, and a solvent using a conventional method. By doing so, it can be obtained as a liquid or paste composition. In the improved flux composition of the present invention, the addition ratio of the specific organic halogen compounds as an activator is as low as that of the solder. It varies depending on the application and conditions, but generally the solid content is 100 weight! 0.0 for 1m. The range is from 1 to 50 parts by weight, preferably from 0.5 to 30 parts by weight. Next, in the improved flux composition of the present invention, FT
By adding mechanical acid in combination, high reliability of corrosion PL1 insulation can be maintained, and at the same time, flux soldering PI-. (Claim 4, Nos. 7 to 7)
Section 9). The organic acid used here is not particularly limited, but
For example, fatty acids such as adipic acid are effective. [Test Example] Next, the effects of the present invention will be explained using a test example. About a composition (this invention) in which a 20% IPA solution of distilled rosin obtained by clear distillation of natural mouth gin is prepared, and 2.5 parts of specific organic halogen compounds are added to this solution per 100 parts of rosin solid content (this invention) f The test described above was conducted and the flux characteristics are shown in Table 1. In addition, a hydrohalide salt and an organic acid were added to the same solution as above, each with a solid content of 100 m! For part a,
The former is 0.5 weight in chlorine conversion loss! Table 2 shows the flux properties of a composition containing 2.5 liters of fluoride (conventional composition) in part a, the latter of which was subjected to a similar test. Details of the test items in both tables are as follows. ◇ Solubility 20 Items that dissolve 1% or more at room temperature ◇ Copper plate corrosion: According to JIS-Z-3197 (observed with a 40x stereo microscope) O No corrosion △ Discoloration of the product × Occurrence of corrosion is observed ◇ Copper Fine wire corrosion: After immersing an annealed copper wire with a diameter of 0.31 in the sample flux for 5 days, the strength of the copper wire taken out was measured using a tensile tester, compared with the blank copper wire, and the corrosion rate was calculated using the following formula. demand. Corrosion rate = (Tensile strength before immersion - Tensile strength after flux immersion) / immersion + 3if tensile strength x 1
00 ◇Copper mirror corrosion: According to JIS-Z-3197 (5000
A, T = IO% (after leaving for 24 hours) O No copper foil dropout Δ Partial dropout × Copper foil significant dropout ◇Solder spread rate: JIS-Z-3197 (Solder temperature 250℃, solder type H-63A) ◇Wetting speed: Solder bath temperature 2 using menisco glass
50°C, immersion time 4 seconds, immersion depth 2-, immersion speed 25+s+/main. Wetting time when conducting a wetting test with a polished copper plate (0.2 x 7 x 30 questions) under the following conditions (time from when the test piece comes into contact with the solder until the wetting angle between the solder and the copper plate becomes 90 degrees) ◇ H4 tension: Solder pass temperature 25 using meniscograph
0°C, immersion time 4 seconds, immersion depth 2cm, immersion speed 25m/sin. Wetting tension after 4 seconds when conducting a wetting test with a polished copper plate (0.2κ7κ3o■) under the following conditions ◇Surface insulation resistance: JIS-7, -3 1 9
71. :． DRY (Used substrate JIS < L-shaped electrode 2g.) DRY:
100°C x 30 minutes WET: 40°C x 90% [1-IX 9 6Hrs. Back (blank below) -548 Comparing and summarizing the results of Table 1 (compositions of the present invention) and Table 2 (known compositions), the results are as follows. ■ Concerning corrosivity, specific organic halogen compounds are used.
The composition used as agent h (Table 1) gave excellent results in all copper plate corrosion, copper fine wire corrosion, and copper mirror corrosion tests, whereas the composition using a known activator (Table 1) In Table 2), organic acids and amine halogen salts showed no corrosion in the copper plate corrosion test.
The degree of corrosion was remarkable in both copper thin wire and copper mirror corrosion wiping tests. (2) In the solderability test, the specific organic halogen compound activator showed approximately the same performance as the known organic acid activator, and there were no practical problems. ■ Regarding insulation, specific organic halogen compounds active P
IE agents are significantly superior to amine halogen salts and organic acids. (2) Regarding aqueous solution resistance, specific organic halogen compounds that do not contain any ionic groups in their molecules are significantly superior to amine halogen salts and organic acids. In summary, the improved flux composition of the present invention using specific organic halogen compounds as an activator has the following properties:
Compared to conventional compositions, that is, flux compositions that use hydrohalides of organic amines, organic acids, and halogen compounds having ionic groups as activators, they are less corrosive and have higher electrical reliability. Moreover, it is clear that there is no practical problem in terms of solderability. Next, as an important feature of the present invention, there is the problem of achieving the problem of no cleaning. As mentioned earlier, in recent years, with the ultra-miniaturization of electronic circuits,
Since a tiny amount of residual flux can cause a decrease in electrical insulation wt, short circuits, and migration, 7-labx cleaning removal is often performed when soldering microcircuit wiring boards and microterminal boards. ing. However, with the tightening of regulations on fluorocarbons, which are the main cleaning agents, there has recently been a strong demand from users for cleaning-free fluxes.
Strong interest has been shown in the RMA type flux specified by IL (US Military Standard). However, the current RMA type flux is M
It has been difficult to obtain sufficient solderability because the types and types of activators that can be used are significantly limited by tests such as aqueous resistance and silver chromate test paper specified in IL. However, the present inventor has discovered that when the specific organic halogen compounds of the present invention, which are compounds that do not contain any ionic groups in their molecules, are used as activators,
It was discovered that a composition which satisfactorily satisfies the above-mentioned MIL regulations and does not require flux cleaning even in soldering of fine channels was obtained, and the present invention was obtained. In this case, it is desirable to sufficiently purify the rosin resin etc. that will serve as the base component by means such as distillation. Next, in the present invention, as mentioned earlier, it has been found that when an organic acid such as a fatty acid is used as an activator together with a specific organic halogen compound, the solderability is improved by four times. In order to specifically explain this, in the flux composition prepared in the same manner as the wipe test samples in Tables 1 and 2, the addition of specific organic halogen compounds was added to each of the flux compositions.
Table 3 shows the results of a test in which 0.1 part of adivic acid was used in combination with each of the two compositions containing 0.5 part of Fjrt]. (Leaving space below) Table 3 Results of combined use of specified Class A halogen compounds and organic acids In the soldering flux composition of the present invention, in addition to the above-mentioned essential components, auxiliaries may be added to the flux composition as necessary. Agents such as a matting agent, a chicken agent, a foaming agent, etc. can be appropriately added and used.

【Example】

Next, the practical effects of the present invention will be specifically explained with reference to Examples. Examples 1 to 5, Comparative Example 1 A rosin-based flux having the following composition was foamed and applied to a copper board on which chip components were mounted, and soldering was performed using a horizontal jet soldering device, and the failure rate (solder failure, bridge) was measured.
, residue, matteness, etc. were visually judged. The results are shown in Table 4. Example l Distilled rosin 20 parts heavy gas 1,4
-dibromo-2-butanol (activator) 0.5 weight 1;
No. PBA* 1st layer 1$I
PA (solvent) 78.5 tertiary butylbenzoic acid Example 2 Distilled rosin 1.4-dibromo-23-butylbenzoic acid (activator) P B A IPA (solvent) Example 3 Distilled rosin α -Promoisobutyric acid ethyl ester (activator) PBA Ir'A (solvent) Example 4 Distilled rosin 2.3-dibromo-2- Butene 20 parts by weight 0.5 parts by weight Ro I heavy M part 78.5 parts by weight by Jugakiro 20 parts by weight 0.5 parts! Part a 1! W weight part 78.5 weight 20 weight! Part a: 0.5 parts by weight, Part M: 78.5 parts by weight, h+ fI (20 parts by weight, 1,4-diol (activator), 0.-5 parts by weight, Natsuro adivic acid (combined activator), 0.1 parts by weight). Department IPA (
Solvent > 79.4 times! n parts Comparative example 1 Distilled rosin 20 parts ethylamine hydrochloride (known activator) 0.25 parts 61 parts PBA
1 part by weight I I) 8 (solvent) 78.75 parts by weight j 1 part 4
As shown in the table, the compositions of Examples 1 to 5 were superior to the compositions of Comparative Examples in terms of defect rate and residue condition.
In particular, it was found that the defect rate of Example 5 in which an organic acid was used in combination was extremely low. (Leaving space below) Examples 6 to 7, Comparative Example 2 Soldering was carried out in the same manner as in Example I using a flux having the following composition, and the results of a solder spreading test and a copper plate corrosion test are shown below. It is shown in Table 5. Tip Example 6 Glycerin (vehicle) 10-weight tAs1
．． 4-dibromo-2-butanol (activator) 0.5% by weight IPA (solvent) 89.5
Case study of Jusuro 7 Glycerin (vehicle) IO Juba part 1.
4-Dibromo-2.3 Butanediyl (activator) 0.5 parts IPA (solvent) 89.5 parts Comparative example 2 Glycerin (vehicle) 10 parts m f
f Glycolic acid (known activator) 1-fold M part I
PA (solvent) 89 parts by weight As shown in Table 5, the compositions of Examples 6 and 7 had
In both cases, the solder spread rate improved, and no corrosion of the copper plate occurred. (Left below) Example 8 Distilled rosin 50 weight ft 1 part 1
．． 4-dipromo-2.3 Butanediol (activator) IIiGial (
A solder paste was prepared by adding 90 parts by weight of solder powder to 10 f'R Pa parts of a flux composition consisting of 5 parts by weight of hydrogenated castor oil (thixotropic agent) and 44 parts by weight of butyl carbitol (solvent). The solder spread rate of this solder paste is determined according to JIS-Z-3.
When measured based on No. 197, it was 93%, which was good. Furthermore, no corrosion was observed in the copper plate corrosion test. Example 9 (Preflux composition) WW grade gum rosin (resin) 3 parts by weight 1.4-dibromo-
2.3 A copper through-hole board (number of through-holes = 500) with a thickness of 1.6 ms+ is immersed in a composition consisting of 0.05 parts by weight of butanediol (activator) and 96.95 parts by weight of toluene (solvent). After coating and drying, 40℃
, leave at 90% RH for 30 days. This board was passed through a hot air reflow oven set at a preheating temperature of 150°C and a main heating temperature of 250°C five times to undergo oxidation treatment, and then the flux used in Comparative Example I was foamed and applied using a horizontal jet soldering device. (soldering bath temperature 250℃), visually inspecting the solder to the copper through-holes, counting the number of through-holes in which the solder has not completely risen to the top copper foil, and determining the defective rate. The results are shown in Table 6. In addition, the preflux composition described in L was coated on a copper foil board, and after drying, it was left in a constant temperature and humidity chamber at 40°C x 90% RH for two months, and the state of corrosion and discoloration was observed. 6
Shown in the table. Comparative Example 3 In an experiment similar to Example 7, the following conventionally known compositions were used as preflux, and the results are shown in Table 6. Phenol-modified mouth gin (resin) Double Mrou WW
Grade gum rosin (resin) 1"RQ part Toluene (solvent) 97 parts by weight Table 6 Examples IO Distilled rosin 20ffl et part 1.4-dibromo-2.3 butanediol (activator) 0.5 parts by weight An experiment similar to Example 1 was conducted using a composition consisting of 79.5 parts by weight of IPA (solvent), and the flux residue on the substrate was washed with methanol 112 and recovered (substrate failure: 20 pieces, (Flux coating volume: approx. 1.29/sheet) After drying half 4 liters of this recovered residual liquid at 105°C,
Partition with chloroform-water, gask U for water layer components
Analyzed by chromatography and liquid chromatography. The other half! a is for ionic halogen-containing dia,
Titration was performed using a 1/IOOON silver nitrate solution using a potentiometric titration device. As a result, for gas chromatography and liquid chromatography, the retention time and retention volume were the same as those of the standard active agent.
This fact confirmed that the activator in the flux residue remained with its original structure (nonionic). Furthermore, the presence of ionic halogen was not recognized by silver nitrate titration and ion chromatography.

Claims (9)

[Claims] (1) A halogenated alcohol is added as an activator to a soldering flux composition that contains one or more of rosin resin, high boiling point vehicle, etc. as a main component and consists of this and a solvent. , an improved soldering flux composition. (2) A soldering flux composition containing at least one type of rosin resin, high boiling point vehicle, etc. as a main component and consisting of this and a solvent is added as an activator to add double bonds between carbon atoms in the molecule. An improved flux composition for soldering, characterized in that it contains a halogenated hydrocarbon in which a halogen element is directly bonded to a carbon atom. (3) A halogenated aliphatic carboxylic acid ester is added as an activator to a soldering flux composition that contains at least one type of rosin resin, high boiling point vehicle, etc. as a main component and consists of this and a solvent. An improved soldering flux composition characterized by: (4) A halogenated alcohol is added as an activator to a soldering flux composition that contains one or more of organic acids, polyhydric alcohols, and derivatives thereof as a main component, and a solvent. An improved soldering flux composition. (5) A soldering flux composition containing one or more organic acids, polyhydric alcohols, and derivatives thereof as a main component and consisting of this and a solvent is added as an activator to the An improved flux composition for soldering, characterized in that it contains a halogenated hydrocarbon having a bond and a halogen element directly bonded to a carbon atom. (6) A halogenated aliphatic carboxylic acid ester is added as an activator to a soldering flux composition comprising one or more organic acids, polyhydric alcohols, and their derivatives as main components, and a solvent. An improved soldering flux composition characterized by: (7) The improved soldering flux composition according to claim 1 or 4, characterized in that an organic acid is added together with a halogenated alcohol as an activator. (8) In claim 2 or 5, the activator is a halogenated hydrocarbon having a double bond between carbon atoms in the molecule and a halogen element directly bonded to the carbon atom. An improved flux composition for soldering, characterized in that an organic acid is also added thereto. (9) An improved flux composition for soldering according to claim 3 or 6, characterized in that an organic acid is added together with a halogenated aliphatic carboxylic acid ester as an activator. .