Browse Prior Art Database

T Shaped Finger Glass Dam

IP.com Disclosure Number: IPCOM000088606D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Aimi, BR: AUTHOR

Abstract

A microminiature circuit structure includes a dielectric substrate having a plurality of solder-wettable connection areas to which a chip is attached by means of solder reflow. Solder-wettable areas are an integral part of conductive line patterns of the substrate.

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T Shaped Finger Glass Dam

A microminiature circuit structure includes a dielectric substrate having a plurality of solder-wettable connection areas to which a chip is attached by means of solder reflow. Solder-wettable areas are an integral part of conductive line patterns of the substrate.

Solder has a tendency to flow along conductive line paths on the substrate, requiring a dam configuration to eliminate, minimize or confine the flow to defined and limited areas.

The concept indicates that such a dam needs not to be continuous at the finger region and that a narrow channel 2 of unprotected electrode of about 1 to 2 mils in width can be tolerated on both sides of the electrode, as long as the channel is terminated at some place along the electrode length.

The exposed channel will normally tin during the dip-soldering operation. The solder surface tension in the channel prevents a solder escape from the joint after the chip is mounted.

Figs. 1, 2 and 3 are illustrative only of possible conductive line configurations, with 1 being the chip-joining site, 2 the conductive tinned channel, and 3 a dam configuration superimposed upon the conductive line 4 and formed of glass or any other suitable material. Dam 3 may terminate off the channel at 5 or 6 depending on available space. The dam 3 is conveniently located on the conductive path dependent upon the overall configuration and design of the substrate conductors.

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