JPS58209497A - Solder paste - Google Patents

Abstract

PURPOSE:To prevent the increase in contact resistance on account of the sticking of the abietic acid evaporated from paste during soldering, by adding specific polyhydric alcohol to the solder paste contg. abietic acid. CONSTITUTION:Polyhydric alcohol of >=4 carbon atoms such as erythritol, sorbitol, PVA or the like is added at 1-20wt% based on the weight of abietic acid to the solder paste contg. abietic acid having volatility as an essential component and contg. ammonium chloride in addition thereto. If soldering is carried out by using such paste, the abietic acid forms polyhydric alcohol and non- volatile ester compd. by the heat during soldering. The evaporation and sticking of the abietic acid are obviated and the increase in the contact resistance on account of the sticking of the abietic acid is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solder paste that can prevent the volatilization of abietic acid contained in the solder paste that occurs during soldering and avoid the formation of an insulating film on contacts. It is.

Conventionally, solder paste contains abietic acid and ammonium chloride as main components. When this paste is used for soldering, abietic acid evaporated from the paste adheres to the surface of the contact of a nearby device, causing an increase in contact resistance or a serious defect.

The present invention specifically provides a solder paste which can prevent the abietic acid contained in the paste from being emitted repeatedly during soldering, thereby avoiding the resulting problems. Specifically, the present invention provides a solder paste containing abietic acid as a main component, which is characterized in that a polyhydric alcohol having a carbon number of 4 or more is added.The present invention will be described in detail below. .

The solder paste according to this invention has gA as a main component! A solder paste containing abietic acid, which becomes volatile as the temperature rises, and ammonium chloride is used.

This solder paste is characterized by the addition of polyhydric alcohol having a carbon number of 54 or more. Polycylindrical alcohols with 4 or more carbon atoms include erythritol, which has 4 carbon atoms in which hydrocarbons are linearly bonded, sorbitol, which has 5 carbon atoms, polyvinyl alcohol, which has a large number of carbon atoms, and early stage novolac-type phenolic resins. In other words, the volatile abietin has the activity of forming an ester bond with alcohol when it receives heat during solder stagnation, and immediately forms a polyhydric alcohol proboscis with a non-transparent alcohol. It generates a substance that is volatile and does not evaporate. Here, if the number of carbon atoms in the alcohol is 3 or more, even if an ester compound is produced, it will be volatile and the initial objective cannot be achieved.

The blending ratio of the hydrocarbon polyhydric alcohol having 4 or more carbon atoms is preferably 1% or more and less than 2011% of the amount of abietin installed in the paste. This is because if it is less than 1% by weight, the present invention will not be effective, and if it is more than 20% by weight, the polyhydric alcohol will thermally decompose, and the decomposition products will volatilize from the paste and adhere to the contacts.

In the case of polyvinyl alcohol, it is preferably 0.5 to 10% by weight based on the abietic acid in the paste. In other words, if it is less than 0.5% by weight, the purpose of this invention will not be achieved;
This is because if the weight exceeds 1%, the purity of the solder against gold and oxide is poor.

In the case of a novolac-type phenol compound at the initial stage, it is preferably 0.5 to 3011% of the abietin in the paste. This is because the effect of the present invention is small if it is less than 0.5 ffif% (and if it is more than 30% by weight, the phenol IM index decomposition of the compound occurs and volatile substances are produced).

Examples of the present invention are listed below in a table. Here, the effect was confirmed by soldering 100 breakers of the same structure, and when the contact resistance at a small point exceeded 5QmΩ, the failure rate was determined.

i (10,0)Oj l (h5.o),'
OH' (2°, .2.1.

i (15
,0ton,0 (!Polyvinyl alcohol C0,5)10'Additive-free, erythritol (0,5M'3%) Novolak type phenolic resin initial layer base material (0,1% bean amount) solder paste. Abietic acid of 1 μy or more was detected in all of the defective contacts used.1. x-+)
1% of paraffin is obtained from 7 good contacts of ○ using solder paste of
Detected at μ2 or more, it is a novolac type phenolic resin initial condensate (30 weight 1%).

(40% by weight) solder paste was used, but phenol and methylene diphenol of 2 μm or more were detected from the defective contacts.

patent applicant Matsushita Electric Works Co., Ltd. Representative Patent Attorney Toshimaru Takemoto (2 others)

Claims (1)

[Claims] (1) A paste containing abietic acid as a main component, which is characterized by adding a polyhedral alcohol having a carbon number of 4 or more.