Browse Prior Art Database

Apparatus for Sealing in a Semiconductor Package

IP.com Disclosure Number: IPCOM000084863D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 4 page(s) / 76K

Publishing Venue

IBM

Related People

Baker, MR: AUTHOR [+4]

Abstract

An apparatus is described for improving the hermetic seal of a soldered cap on a semiconductor module by employing a dual-speed article advancing mechanism.

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Apparatus for Sealing in a Semiconductor Package

An apparatus is described for improving the hermetic seal of a soldered cap on a semiconductor module by employing a dual-speed article advancing mechanism.

Fig. 1 illustrates a conventional dual-in-line module with the substrate 1 molded about the electrodes 2, which communicate into the substrate cavity 3 to make contact with the semiconductor device 3'. Located about the periphery of the cavity 3 is the metal ring 4 which serves as the bonding point for the cap 6 when the solder ring 5 is reflowed.

Conventional techniques for reflowing the solder ring 5 include passing an electric current therethrough while the metal ring 4, solder ring 5, and metal cap 6 are in mechanical contact, thereby fusing the solder and sealing the cap to the substrate. These prior art techniques, however, do not always result in a good hermetic seal since the solder does not always adequately reflow in the corner areas 5a of the solder ring 5.

The apparatus described herein overcomes the tendency of the prior art techniques for reflowing the solder ring 5, to fail to adequately reflow the corner regions 5', by employing a dual-speed advance for the module during the soldering operations. Figs. 2a and 2b illustrate the principle of the apparatus described. The substrate 1, solder ring 5, and metal cap 6 are positioned in mechanical contact with one another on the carriage block 7.

The current electrodes 10 are brought into contact with the respective corners of a first side 6' of the metal cap 6. Current is then passed through the series arrangement of the electrodes 10, side 6' of metal cap 6 and side 5' of solder ring 5, thereby reflowing the solder in side 5'.

In the prior art techniques, the metal cap 6 is then passed beneath the electrodes 10 in the X direction at a constant speed to reflow the solder along the sides 5'' and 5''''. As the cap 6 moves with respect to the electrodes 10, a liquid- solid interface propagates through sides 5'' and 5'''' of the solder ring 5 at some distance in front of the electrodes 10.

It has been discovered that sealing failures at the corners 5a of the solder ring 5 arise, because the side 5' was not sufficiently melted to form a good bond with the metal ring 4 and metal cap 6. To remedy this the apparatus described herein, heats the side 5' of the solder ring 5 for a relatively longer period of time than for other portions of the solder ring 5, by slowing the advance of the carriage 7 in the X direction during the first portion of the solder reflow operation for the sides 5'' and 5''''.

After sides 5'' and 5'''' have been reflowed by passing the cap 6 completely beneath the electrodes 10, the carriage block 7 rotates through an angle of 90 degrees about an axis perpendicular to the X-Y plane so that the...