Browse Prior Art Database

Alignment Fixture for Radio Frequency Shield to Deck Reflow

IP.com Disclosure Number: IPCOM000107733D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Bouchard, MA: AUTHOR [+3]

Abstract

Optical modules must have receiver and transmitter functions isolated from each other to minimize the effect of cross-talk on receiver sensitivity.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 94% of the total text.

Alignment Fixture for Radio Frequency Shield to Deck Reflow

       Optical modules must have receiver and transmitter
functions isolated from each other to minimize the effect of
cross-talk on receiver sensitivity.

      Both the receiver and the transmitter functions on a single
Metallized Ceramic (MC) substrate.  Consequently, a Radio Frequency
(RF) shield is needed to isolate the receiver from the transmitter
(see Fig. 1).

      The RF shield is attached to the center row of pins with solder
by reflowing solder on the substrate.  The shield is made out of
beryllium copper alloy and it is gold plated.  However, it is very
light in weight, in comparison to the surface tension forces of the
molten solder.  Hence, it is difficult to maintain its position on
the substrate which results in a yield loss.

      To eliminate the problem, the fixtures were designed to
straddle the RF shield during substrate relow.  These fixtures were
made out of the lids that are used during subsequent assembly, thus
maintaining the needed alignment of the shield  for later assembly.
The rails of the lids (see Fig. 2) that fit in the housing are used
during the reflow.  The notches are cut in the center of the fixture
that straddle the RF shield to maintain needed alignment of shield to
substrate.  The fixture looks like a frame, with all unneccessary
material removed.  This minimizes the thermal mass and, as a
consequence, no changes are required to the existing proc...