Senju Metal Industry Co., Ltd.

Sakie Okada

Kengo Ohta

Shunsaku Yoshikawa

Naoko Hirai

Shuta Akatsuka

Hideyuki Komuro

Keitaro Shimizu

Taro Itoyama

Motoki Koroki

Ryuji Ukai

Keisuke Shinozaki

Kenta Inoue

Kazuya Kitazawa

Hiroaki Kawamata

Yutaka Hashimoto

Tomohiro Yamagame

Hayato Kaise

Syuta Akatsuka

A solder paste includes a solder powder and a flux. The flux includes a rosin, an activator, a solvent, and a thixotropic agent containing a polyethylene glycol. A content of the polyethylene glycol is 10 mass % to 20 mass % with respect to a total mass of the flux, a content of the thixotropic agent excluding the polyethylene glycol is 5 mass % or less with respect to the total mass of the flux, and a content of the rosin is more than 15 mass % and 50 mass % or less with respect to the total mass of the flux.

Solder paste

A flux containing: a rosin; a solvent (S); a thixotropic agent; and an activator is disclosed. The rosin contains a rosin amine. The solvent (S) contains a first solvent (S1) having a boiling point of 250° C. or less, and the amount of the first solvent (S1) relative to the total amount of the solvent (S) is 50% by mass or more and 100% by mass or less.

Flux and solder paste

Provided herein is a flux which contains a rosin, a rosin amine; one or more types of organic sulfonic acid selected from the group consisting of an alkane sulfonic acid, an alkanol sulfonic acid, and an aromatic sulfonic acid, a thixotropic agent, and a solvent, wherein: the rosin content is 5-50 mass %, inclusive, of the total amount (100 mass %) of the flux, the rosin content is 5-30 mass %, inclusive, of the total amount (100 mass %) of the flux, the organic sulfonic acid content is 0.2-10 mass %, inclusive, of the total amount (100 mass %) of the flux, and the proportion (mass ratio) of the rosin amine content to the organic sulfonic acid content is 3.33-10, inclusive.

Provided is flux containing rosin-based resin, a solvent, a thixotropic agent and an activator. The thixotropic agent includes any or both of hardened castor oil and bisamide-based thixotropic agent. The contents of the hardened castor oil and the bisamide-based thixotropic agent are respectively within the range of 4 wt. % or more and 10 wt. % or less and the range of 1 wt. % or more and 5 wt. % or less based on the total weight of the flux. The contents of the thixotropic agent are within the range of 5 wt. % or more and 15 wt. % or less based on the total weight of the flux. The activator includes hydrohalide, a halogenated aliphatic compound and an imidazole compound. The contents of the halogen in the flux are within the range of 9000 ppm or more and 50000 ppm or less.

Flux and solder paste using the same

A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste exhibits high joint strength at room temperature and at high temperatures, excels in terms of temporal stability, exhibits minimal void formation, and can form highly cohesive joints. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: a powdered intermetallic compound that comprises copper and tin and has metal barrier layers covering the surfaces thereof and a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

A method of printing solder paste on a substrate through minute apertures in a mask member, in which the solder paste is supplied to the apertures of the mask member under less than atmospheric pressure and has a viscosity so that the solder paste is filled in the apertures under atmospheric pressure. It is preferable that the solder paste has a viscosity of 50 through 150 Pa&#xb7;s and a thixotropic ratio of 0.3 through 0.5. Further, the solder paste is obtained by mixing a flux containing solvent having a boiling point such that volatilization thereof is suppressed under the less than atmospheric pressure and solder powders. It is preferable that in the flux, the solvent having the boiling point of 240&#xb0; C. or more is used and the solvent is octanediol.

Method of printing solder paste

A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste excels in terms of temporal stability and exhibits high joint strength at room temperature and at high temperatures. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: 10-70 mass % of a powdered intermetallic compound comprising copper and tin and 30-90 mass % of a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Growing community of inventors

Tokyo, Japan

Sakie Okada