Senju Metal Industry Co., Ltd.

Sumitomo Bakelite Company Limited

Tomohisa Kawanago

Takahiro Nishizaki

Hiroyoshi Kawasaki

Masato Shiratori

Miyuki Hiraoka

Kaichi Tsuruta

Hiroki Oshima

Atsushi Ikeda

Yasuhiro Kajikawa

Takeo Saitoh

Naokatsu Kojima

Tatsuya Kazama

A flux containing an organic acid (AC1), a solvent (S1), and a compound (AZ1) that has a benzotriazole skeleton is employed. AC1 has a rate of decrease in weight of 20% by mass or less in a case of being held at 140° C. for 15 minutes. S1 has a rate of decrease in weight of 50% by mass or less in a case of being held at 140° C. for 15 minutes.

Flux and solder paste

Provided is flux that can achieve a low residue so as to make it possible to ensure solder wettability, ensure holding properties of a solder ball, and suppress the amount of residue after soldering and enable application for use without washing. The flux includes 1-15% by weight of an organic acid mixture comprising an organic acid with 10 or more carbon atoms, 50-90% by weight of isobornyl cyclohexanol, and 5-45% by weight of a different solvent. The proportion of the isobornyl cyclohexanol is 50-95% by weight, where 100% by weight is the total of the isobornyl cyclohexanol and the different solvent. The organic acid mixture comprising the organic acid with 10 or more carbon atoms comprises 2-methylnonanedioic acid, 4-(methoxycarbonyl)-2,4-dimethylundecanedioic acid, 4,6-bis(methoxycarbonyl)-2,4,6-trimethyldecanedioic acid, and 8,9-bis(methoxycarbonyl)-8,9-dimethylhexadecanedioic acid.

Provided is a flux which is rosin-free and contains 50% by mass or more and 90% by mass or less of 2,4-diethyl-1,5-pentanediol, more than 0% by mass and less than 50% by mass of a solvent, 1% by mass or more and 15% by mass or less of an organic acid, wherein the total amount of the 2,4-diethyl-1,5-pentanediol and the solvent is 83% by mass or more and 99% by mass or less. This flux does not require washing with an organic detergent when transferred to solder balls is provided.

Flux

A flux in which solder wettability can be maintained and with which it is possible to suppress the amount of residue after soldering and realize low residue. This flux includes 65-99 wt % of a solvent, and also includes 1-13 wt % of at least one acid selected form a dimer acid that is a reaction product of oleic acid and linoleic acid; a trimer acid that is a reaction product of oleic acid and linoleic acid; a hydrogenated dimer acid obtained by hydrogenating dimer acid that is a reaction product of oleic acid and linoleic acid; and a hydrogenated trimer acid obtained by hydrogenating a trimer acid that is a reaction product of oleic acid and linoleic acid.

The present invention provides a method for manufacturing an electronic device including a base material that has an exposed metal portion on a surface of the base material and an electronic component that is provided on the base material. The method includes a flux treatment step of treating the exposed metal portion with a flux by bringing the exposed metal portion into contact with the flux and an introduction step of introducing a resin composition such that the resin composition comes into contact with a surface of the exposed metal portion treated with the flux. The flux contains a rosin, an activator, and a solvent. The content of the rosin is equal to or greater than 1 part by mass and equal to or smaller than 18 parts by mass with respect to 100 parts by mass of the flux. The percent change in mass of the flux before and after a heating treatment is equal to or lower than 21% by mass. The resin composition contains an epoxy resin and a phenolic resin curing agent. In a case where SP1 represents a Hansen's method-based average solubility parameter of a resin group consisting of the epoxy resin and the phenolic resin curing agent in the resin composition, and Mn1 represents a number average molecular weight of the resin group, SP1 and Mn1 satisfy Mn1&#x2264;210&#xd7;SP1&#x2212;4,095.

Method for manufacturing electronic device

Provided is a flux capable of obtaining predetermined rheological characteristics both at room temperature and under a thermal history that is assumed for soldering and capable of suppressing the amount of a residue after soldering to realize a low residue. The flux contains a first alcohol compound that has two or more OH groups and has a melting point of lower than 25&#xb0; C. and a second alcohol compound that has two or more OH groups and has a melting point of higher than 25&#xb0; C., the first alcohol compound is glycerin, the second alcohol compound is 2,5-dimethylhexane-2,5-diol, the flux has a viscosity of 10 Pa&#xb7;s or more and 50 Pa&#xb7;s or less at 25&#xb0; C. and has a viscosity of more than 0 Pa&#xb7;s and 1 Pa&#xb7;s or less at 100&#xb0; C., and, in a case where 10 mg of the flux is heated up to 25&#xb0; C. to 250&#xb0; C. under a Natmosphere at a temperature rise rate of 10&#xb0; C./min, the weight of the flux after heating is 15% or less of the weight of the flux before heating.

An object of the present invention is to provide a flux which does not precipitate a crystal and can improve solder wettability. A flux comprising 0.4 to 10.0 mass % of ditolylguanidine and 1.0 to 10.0 mass % of an organic acid, and not comprising diphenylguanidine as an amine compound.

A solder ball according to the present invention contains 0.2 to 2.2% by mass of Zn, and a balance of Sn, and has a spherical diameter of 0.1 to 120 &#x3bc;m and a yellowness (b*) in an L*a*b* color system of 2.70 or more and 9.52 or less. An oxide film is formed by performing aging treatment. By producing a solder ball having a yellowness of 2.70 or more and 9.52 or less, it is possible to suppress the growth of a CuSn layer and/or a Cu&#x2014;Zn(&#x2014;Sn) layer during joining.

Growing community of inventors

Tochigi, Japan

Tomohisa Kawanago