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Title:
METHOD OF SURFACE MOUNTING OF SEMICONDUCTOR ELEMENT
Document Type and Number:
Japanese Patent JPH03191593
Kind Code:
A
Abstract:

PURPOSE: To surely mount even a QFP in which the tip of a lead is levitated high by using an L-shaped needlelike shape memory alloy pin whose tips are bent so as to come into close contact when heat is applied.

CONSTITUTION: A long hole is made at the tip part of a lead 1 of a semiconductor element of a quad flat package(QFP) 3 or the like. On the other hand, a needlelike shape memory alloy pin 4, of about 0.1mm in diameter, which is L-shaped at room temperature and which is provided with a property that L-shaped tips are bent in the direction coming into contact with each other at a high temperature of about 140°C is mounted after the surface of a pad 6 on a printed circuit board 5 has been coated with a solder paste 2. Then, the QFP 3 is mounted in such a way that a vertically erected side of the shape memory alloy 4 is inserted into the hole at the tip of the lead 1. When the printed circuit board 5 is put into a reflow apparatus and heat is applied, the L-shaped tip of the shape memory alloy 4 is bent and holds the tip of the high leviated lead 1 in a state that the tip is pressed so as to come into contact with the solder paste 2. Thereby, a part which is not soldered is never produced.


Inventors:
NUMATA TORU
Application Number:
JP33206889A
Publication Date:
August 21, 1991
Filing Date:
December 20, 1989
Export Citation:
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Assignee:
NEC CORP
International Classes:
H05K1/18; H01L23/50; H05K3/34; (IPC1-7): H01L23/50; H05K1/18; H05K3/34
Attorney, Agent or Firm:
Uchihara Shin



 
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