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Browse Prior Art Database

Integrated Test Via and Pad Design

IP.com Disclosure Number: IPCOM000121333D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Cipolla, TM: AUTHOR [+6]

Abstract

It is advantageous to be able to make contact between the leads of surface-mounted components to be mounted on dielectric substrates and the pads on underlying metal levels in the dielectric structure of the substrates. In general, this is accomplished by manufacturing plated- through holes into the dielectric substrate. If the contact could be established through the use of solder used in the component joining process, then the need for plated-through holes would be eliminated. However, electrical contact and complete solder coverage must be confirmed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 78% of the total text.

Integrated Test Via and Pad Design

      It is advantageous to be able to make contact between the
leads of surface-mounted components to be mounted on dielectric
substrates and the pads on underlying metal levels in the dielectric
structure of the substrates.  In general, this is accomplished by
manufacturing plated- through holes into the dielectric substrate.
If the contact could be established through the use of solder used in
the component joining process, then the need for plated-through holes
would be eliminated.  However, electrical contact and complete solder
coverage must be confirmed.

      The solution to the problem is the integrated bonding pad and
test via design shown in the figure.  An upper-level metal pad with a
large center opening is placed to insure good mechanical joint
integrity.  However, electrical contact must be made to the
lower-level metal bonding pad. To achieve this, a dielectric through
via is located under the upper bonding pad to allow access to the
lower-level metal.  In addition, a small through via is fabricated in
the lower-level metal pad.  Adequate solder wetting of the recessed
bonding pad may be observed as solder reflows through the metal via
onto the opposite side of the substrate.  While the figure shows a
two-level metal structure, he design is applicable for any number of
metal levels.  The solder wets both the upper- and lower-level metal
surfaces.  The upper surface provides intimate contact for mechanical
...