Browse Prior Art Database

Compliant Fluxer to Maintain Parallelism with Respect to Substrate

IP.com Disclosure Number: IPCOM000110436D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 60K

Publishing Venue

IBM

Related People

Elenius, PM: AUTHOR [+2]

Abstract

Flux is commonly applied to the metallic pads of electrical components, such as ceramic substrates and semiconductor chip before the solder joining process to remove the oxide layer which forms on the metallic pads. It is desirable to obtain a smooth and uniform flux coverage over the surface to be joined. With small electrical components, the size of semiconductor chip or a very small ceramic substrate, the flux pattern is approximately 2 to 3 millimeters square, it is easy to obtain a smooth and uniform flux coverage. However, with larger ceramic substrates on the order of 15 millimeters square or above, it is common to get a heavy flux application on one side of the flux pattern.

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Compliant Fluxer to Maintain Parallelism with Respect to Substrate

      Flux is commonly applied to the metallic pads of electrical
components, such as ceramic substrates and semiconductor chip before
the solder joining process to remove the oxide layer which forms on
the metallic pads.  It is desirable to obtain a smooth and uniform
flux coverage over the surface to be joined.  With small electrical
components, the size of semiconductor chip or a very small ceramic
substrate, the flux pattern is approximately 2 to 3 millimeters
square, it is easy to obtain a smooth and uniform flux coverage.
However, with larger ceramic substrates on the order of 15
millimeters square or above, it is common to get a heavy flux
application on one side of the flux pattern.

      The nonuniformity was traced to a very slight nonparallelism
between the flux head and the substrate.  A typical flux head is
connected by a rigid, straight shaft which cannot conform to slight
irregularities in the metallic pads or substrate, but maintains a
constant angle with respect to the substrate regardless of whether
the flux head is fully contacting the pad.  The side of the head
which was not in intimate contact with the substrate pads has less
resistance to the flux flow and develops significantly heavier and
thicker flux patterns.  This problem was corrected by giving the flux
head compliance to the substrate.  The compliance allows the flux
head to always make intimate contact over the en...