Browse Prior Art Database

Cast Solder Preloading for Stacked Modules

IP.com Disclosure Number: IPCOM000088616D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Rivenburgh, DL: AUTHOR [+2]

Abstract

The technique described below provides a means of selectively applying a specific volume of solder in the form of a cone, cylinder, or sphere on pins used for stacking a number of printed-circuit modules on top of each other, such as those shown in U. S. Patent 3,999,105.

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Cast Solder Preloading for Stacked Modules

The technique described below provides a means of selectively applying a specific volume of solder in the form of a cone, cylinder, or sphere on pins used for stacking a number of printed-circuit modules on top of each other, such as those shown in U. S. Patent 3,999,105.

The solder, in the form of balls, washers, etc., are loaded into the reflow fixture with the aid of vacuum and vibration. The reflow fixtures can be made out of any material which will not contaminate the solder or will not be wetted by the solder, such as anodized aluminum, stainless steel and graphite.

The design of the fixture allows the solder to be loaded in any form and easy application of flux. Through holes are provided for degassing and pin location, and the hole geometry provides the desired geometric shape after reflowing. The process is as follows: 1. Load the reflow fixture with desired solder volume and

form (Figs. 1 and 2).

2. Flux solder in reflow fixture and pin; on deck (Fig. 1).

3. Load deck into position on the reflow fixture.

NOTE: Weight of deck restricts solder movement during

flux activation (Fig. 1).

4. Reflow solder. At this point pins fall into through

holes and solder takes desired geometry.

5. Cool, clean, disassemble and store loaded deck.

The advantages of this method are:

1. Volume control

2. Inspectability

3. Avoid shorts from otherwise loose solder

4. Ease of loading

5. One end already joined

6. Off-line method of apply...