JPH0588279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an adhesive for bonding small parts such as chip parts to a substrate when soldering them with cream solder. This invention relates to a temporary soldering adhesive for fixing parts after cream solder is applied to a board and chip parts are mounted until soldering is completed. BACKGROUND ART In recent years, electronic boards have tended to become smaller and smaller, and as components have become smaller and their packaging density has increased, the use of cream solder and chip components has increased. Ordinary electronic components have the necessary and sufficient lead wires to secure, wire, and solder the components, but chip components require sufficient leads to secure the components in order to enable high-density mounting of components. There are no lines. Therefore, it is difficult to fix leadless components on a substrate, and they are likely to be misaligned when the substrate is moved or heated and melted. In order to prevent this, a method has been proposed in which parts are bonded in advance with thermosetting resin such as epoxy, but with this method, if the adhesive adheres to the surface to be soldered, the soldering will be interrupted. becomes impossible. Also, wax - a composition made from higher fatty acids is sometimes used to fix parts, etc., but it lacks the adhesiveness necessary to reliably bond parts, etc., and is brittle and cracks when cold. Because it melts and flows with heat of about 100℃, parts can easily fall or shift when the board is moved or heated and melted.
Cleanability is poor. Purpose of the Invention The present inventors have conducted various studies in search of a composition that has sufficient adhesion, tackiness, and elasticity, does not inhibit soldering or flow when heated, and has good cleaning properties. As a result, the present invention was completed. The present invention is a solder that does not inhibit soldering but rather promotes soldering, does not flow due to heat during soldering, has sufficient component adhesive strength, and can be easily cleaned. Provide temporary adhesive for attachment. Structure of the Invention The present invention includes a mixture of a rosin resin, a thickener, and a plasticizer, and the thickener is organic bentonite, bentonite, kaolin, talc, clay, ultrafine silica, hydrophobic ultrafine silica, and ultrafine alumina. and metal soap, with an acid value of 20 or more,
Provides a temporary soldering adhesive that is solid at room temperature and has a viscosity of 1000 cps or more at 80°C. The rosin resin used in the present invention has a softening point
A resin having a temperature of 60 to 140°C is suitable, and may or may not have an acid value. Does not have an acid value or
If it is relatively small, components with an acid value are added as plasticizers and additives so that the final product has an acid value of 20 or more, preferably 50 or more. The adhesive of the present invention has adhesive properties and does not adversely affect later soldering properties, but rather contributes to it,
It is particularly preferable that the acid value is 20 or more. As the rosin resin used in the present invention, natural rosin, hydrogenated rosin, disproportionated rosin, maleic acid-modified rosin, phenol-modified rosin, polymerized rosin, and rosin polyhydric alcohol ester are preferable.
Particularly preferred is hydrogenated rosin. Since hydrogenated rosin is hydrogenated, it has excellent heat resistance and oxidation resistance, is non-polymerizable, exhibits good detergency, and has a good acid value. The thickener used in the present invention imparts appropriate viscoelasticity to the adhesive, so that when bonding electronic components, it does not flow out from the bonded area, making it easy to apply locally, and provides sufficient strength to fix the electronic components after bonding. It is for the purpose of
It is a solid powder at room temperature and adhesive application temperature. It is preferable to use particles with a particle size of 70 μm or less, particularly 40 μm or less. Thickeners include high melting point organic fine powders and inorganic fine powders, but it is preferable to use inorganic fine powders from the viewpoint of viscosity properties during heating. Examples include organic bentonite, bentonite, kaolin, talc, clay, ultrafine silica, hydrophobic ultrafine silica, and ultrafine alumina. Particularly preferred is organic bentonite, which does not easily deteriorate solderability or cleanability and has a large viscosity adjusting effect. In the present invention, a plasticizer may be added if desired. The role of the plasticizer is mainly to adjust the hardness of the adhesive, adjust the viscosity during melting, and eliminate the brittleness of the bonded part after bonding. Alternatively, if the adhesive does not have a sufficient acid value, it gives the adhesive an acid value. The plasticizer is preferably one that dissolves the rosin resin well and is liquid at room temperature. Plasticizers used in the adhesive of the present invention include general plasticizers and solvents such as phosphate esters, acidic phosphate esters, aliphatic dibasic acid esters, phthalate esters, polyamides, polyalkylene glycols, and glycoethers. However, it is inappropriate to include components that evaporate during heating. This is because it evaporates during heating and causes misalignment of parts. Further, the liquid resin is preferably a substance that dissolves well in organic solvents, does not polymerize, and has appropriate polarity. Therefore, methyl ester of hydrogenated rosin, hydroabiethyl alcohol, and dimer acid are preferred, and methyl ester of hydrogenated rosin is particularly preferred, as it has extremely good compatibility with the solid resin used in the present invention, dissolves well in organic solvents, It has moderate adhesiveness and has desirable properties in forming the properties of the composition. The adhesive of the present invention may contain other suitable additives used in soldering fluxes. Various additives in the present invention include, for example, antioxidants, soldering activators, organic acids, nitrogen-containing bases, surfactants, organic solvents, corrosion inhibitors, frosting agents, antifoaming agents, thermosetting resins, Examples include rubber. As antioxidants, phenol type, sulfur type,
Examples include phosphorus-based, tin-based, oxime-based, and amine-based antioxidants, but phenol-based antioxidants are particularly preferred;
Particularly effective is 2,6-di-tert-butyl-p-cresol. Typical nitrogen-containing base hydrohalides can be used as soldering activators, such as cyclohexylamine hydrohalides (HF,
HCl, HBr, HI), etc. As the organic acid, aliphatic carboxylic acids, aliphatic dicarboxylic acids, aromatic carboxylic acids, oxycarboxylic acids, etc. can be used, but benzoic acid, chlorobenzoic acid, and salicylic acid are effective from the viewpoint of cleaning properties. Examples of nitrogen-containing bases include aliphatic amines, aromatic amines, amino acids, alkanolamines, nitrogen-containing heterocyclic compounds, polyamines, amides, guanidine, hydrazine, oximes, and the like. In particular, cyclohexanone oxime is more effective in terms of adhesiveness and solderability. When using these, the amine value of the entire adhesive is 10 or more, preferably
It is best to mix it so that it becomes 20-160. The surfactant is preferably a nonionic surfactant, and preferably does not contain sulfur. Alcohols, alkanolamines, polyalcohols, glycoethers, esters, ketones, hydrocarbons, and the like can be used as organic solvents, but it is better to avoid using volatile ones. The corrosion inhibitor is preferably a nitrogen-containing corrosion inhibitor such as benzotriazole, octylamine, dicyclohexylamine, but is not limited thereto. Particularly preferred is benzotriazole. If a frosting effect is required, a conventional frosting agent may be appropriately added. As antifoaming agents, silicone-based antifoaming agents are effective, and those with large molecular weights are particularly effective. The preferred compounding ratio of the temporary soldering adhesive of the present invention is 40 to 80% by weight of rosin resin, particularly 45 to 70% by weight,
3 to 30% by weight of thickeners, especially 5 to 15% by weight, plasticizers 0 to 60% by weight, especially 10 to 40% by weight, and 0 to 15% by weight of other additives, especially 0 to 4% by weight. . If flux action is not required, an acid value is not necessarily required, but it is preferably 20 or higher, especially 50 to 50.
It has an acid value of 160. The adhesive of the present invention is solid at room temperature and must be melted during soldering. In addition, due to operational requirements when bonding electronic components to base materials, the temperature is 1000 cps at 80℃.
Above all, it is particularly desirable to have a viscosity of 5,000 to 12,000 cps. Effects of the Invention The composition of the present invention stably adheres micro parts, does not flow even when heated, and can keep the parts fixed in a predetermined state. It also cracks at low temperatures,
No peeling occurs. Furthermore, even if the composition adheres to the joint surface, it does not inhibit soldering. In addition, it has excellent solderability and is easy to clean. The present invention satisfies the conflicting characteristics required of adhesives and fluxes, and is very effective in accurately and reliably joining electronic components such as chip components. Example 1 The following components were blended and kneaded at 120° C. for 20 minutes using a stirrer such as a dissolver to obtain a temporary soldering adhesive with a uniform composition. Formula Parts by weight Hydrogenated rosin (acid value 160) 45 Methyl ester of hydrogenated rosin 45 Organic bentonite 10 The obtained adhesive had an acid value of 75, was solid at room temperature, and had a viscosity of 6000 cps at 80°C. . The adhesive force, fluidity, solderability, and cleanability of this adhesive were evaluated as follows. Solderability Apply 100mg of adhesive to a copper plate (30mm ² × 0.3mm),
0.3 g of solder (tin 60/lead 40) was placed on it, heated at 250°C for 30 seconds, and the spread of the solder was observed (number of samples: 5). ○: More than 80% spread for all samples. △: Less than 80% in one part of the sample. ×: Solder becomes beads and does not spread. Cleanability The adhesive was cleaned with the boiling point of a fluorine solvent (Mitsui Fluorochemical Co., Ltd.: Freon TES), and its cleanability was evaluated. ○: Completely washed within 1 minute △: Partially washed within 1 minute ×: Hardly washed within 1 minute. Adhesiveness: Adhesive is used on glass/epoxy resin substrate.
A weight of 5 g was glued and allowed to fall naturally from a height of 50 cm (number of samples: 5). 〇: Weights could not be removed from all samples △: Weights were removed from some of the samples ×: Weights were not attached Fluidity Adhesive was printed on a copper plate, left at 120℃, and the adhesive flowed The gender was evaluated. 〇: No flow at all △: Partial flow ×: Complete flow. The results are shown in Table-1. Example 2 An adhesive was prepared in the same manner as in Example 1 except that the following formulation was used. Formula Parts by weight Methyl ester of hydrogenated rosin 43 Hydrogenated rosin 43 Organic bentonite 9 2,6-di-tert-butyl-p-cresol 0.5 Cyclohexylamine HBr 1.5 Monochlorosalicylic acid 0.5 Cyclohexanone oxime 0.5 Polyoxyethylene nonyl phenyl ether ( 9 mol of EO) 1 Benzotriazole 0.5 Silicone antifoaming agent 0.5 The acid value of the obtained adhesive was 70 and the amine value was 5. The viscosity at 80°C was 6200 cps. The test results are shown in Table-1. Comparative Examples 1 to 4 Adhesives were obtained in the same manner as in Example 1 except for the following formulations. [Formulation of Comparative Example 1] Parafine wax 90 Stearic acid 10 [Formulation of Comparative Example 2] Carnauba wax 90 Stearic acid 10 [Formulation of Comparative Example 3] Ethylene-vinyl acetate copolymer 80 Carnauba wax 20 [ Prescription of Comparative Example 4] Epoxy adhesive [Table]

Claims (1)

[Claims] 1 Contains a rosin resin, a thickener, and a plasticizer, and the thickener is organic bentonite, bentonite, kaolin, talc, clay, ultrafine silica,
Selected from hydrophobic ultrafine silica, ultrafine alumina, and metal soap, acid value 20 or higher, solid at room temperature, 80
Temporary soldering adhesive with a viscosity of 1000 cps or more at °C. 2. The adhesive according to claim 1, wherein the rosin resin has a softening point of 60 to 140°C. 3. Claim 1 in which the rosin resin is selected from natural rosin, hydrogenated rosin, disproportionated rosin, maleic acid-modified rosin, phenol-modified rosin, polymerized rosin, and rosin polyhydric alcohol ester.
Adhesives listed in section. 4. The adhesive according to claim 1, wherein the rosin resin has an acid value of 10 or more. 5 Plasticizer is hydrogenated rosin methyl ester,
The adhesive according to claim 1, which is selected from hydroabiethyl alcohol and dimer acid. 6. The adhesive according to claim 1, which contains a soldering activator having an amine value of 10 or more. 7. The adhesive according to claim 1, which has an acid value of 50 or more.