Leadless chip carrier assembly and method

Details Leadless chip carrier assembly and method Leadless chip carrier assembly and method

1987-06-23

1988-08-02

Ramsey, Kenneth J.

Metal fusion bonding

Process

Plural joints

219 85BM, H05K 1304, H05K 334

Patent

active

047609486

ABSTRACT:
A leadless ceramic chip carrier (LCCC) is soldered to mating conductor pads on a circuit board by depositing a layer of solder paste on peripheral contact pads and on an array of central pads on the board. The same solder paste type and melt temperature are used for both peripheral and central pads. the contact pads of the LCCC are placed on the solder layers and the assembly exposed to infrared radiation from above or other energy source. The LCCC body shades the solder on the central pads resulting in the solder layers at the peripheral pads melting first. The solder on the central pads then melts and balls up due to surface tension lifting the LCCC away from the board stretching the melted solder at the peripheral pads which make the electrical connections to the LCCC contacts.

REFERENCES:
patent: 3458925 (1969-08-01), Napier et al.
patent: 3486223 (1969-12-01), Butera
patent: 3522407 (1970-08-01), Costello
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patent: 3829601 (1974-08-01), Jeannotte et al.
patent: 4195195 (1980-03-01), Miranda et al.
patent: 4475007 (1984-10-01), Ohno
patent: 4545610 (1985-10-01), Lakritz et al.
patent: 4581680 (1986-04-01), Garner
patent: 4600970 (1986-07-01), Bauer
"Soldering Techniques for Surface Mounted Leadless Chip Carriers," by: R. G. Spiecker et al., presented at Int'l. Society for Hybrid Microelectronics (ISHM), Atlanta, GA, Oct. 6-8, 1986.
"Development of a New Micro-Solder Bonding Method for VLSI's," by R. Satoh et al., IEPS Proceedings, 1983, pp. 455-461.

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