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Ball Grid Array Solder Ball Joint on Ball Grid Array Dimple Pad

IP.com Disclosure Number: IPCOM000118769D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Kusumoto, M: AUTHOR [+2]

Abstract

Disclosed is a method of Ball Grid Array (BGA) solder ball joint consisting of a BGA solder ball and a BGA dimple pad. The joint method has the following advantages: 1. higher BGA solder ball assembly accuracy 2. higher BGA solder ball assembly yield

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Ball Grid Array Solder Ball Joint on Ball Grid Array Dimple Pad

      Disclosed is a method of Ball Grid Array (BGA) solder ball
joint consisting of a BGA solder ball and a BGA dimple pad.  The
joint method has the following advantages:
  1.  higher BGA solder ball assembly accuracy
  2.  higher BGA solder ball assembly yield

      The Figure shows a fundamental structure of the BGA solder ball
joint on the BGA dimple pad which has a cavity at the center of the
pad.  The cavity can be formed easily with etching-down techniques.
The joint method has excellent accuracy and yield superior to the
conventional joint method which consists of a BGA solder ball and a
BGA flat pad.  When such incorrect soldering conditions as
insufficient solder reflow temperature profile and/or flux volume are
given, the conventional joint method sometimes has BGA solder ball
bridge defects  between adjacent BGA solder balls due to the movement
of the BGA solder ball on the flat pad attendant upon the spread out
of flux and solder.  The reason for the excellent accuracy and yield
are: the BGA solder ball is pulled into perfect alignment with the
cavity of the BGA  dimple pad.

      The observation of the visual inspection of the BGA solder ball
joint has shown that there were no substantial defects, such as
bridges and misalignments.