×

Method for enhancing fatigue life of ball grid arrays

  • US 6,283,359 B1
  • Filed: 08/23/2000
  • Issued: 09/04/2001
  • Est. Priority Date: 04/30/1998
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for making solder electrical interconnections in an electronic component assembly comprising the steps of:

  • applying a first solder having a first melting point to first pads on the surface of a first substrate of an electronic component assembly;

    forming a solder structure comprising;

    an inner core of a second solder having a second melting point which is higher than the melting point of the first solder to which the structure is to be bonded;

    a layer of a metal wettable by the first solder and having a melting point higher than the second melting point of the second solder of the inner core;

    an outer layer of a third solder having a third melting point which provides a wettable surface for attachment of the solder structure and passivates the layer of metal from oxidation and corrosion, the third melting point being lower than the second melting point;

    bonding the solder structure to the first pad by reflowing the first and third solders;

    applying a fourth solder to second pads on the surface of a second substrate of the electronic component assembly;

    positioning the second pads on the surface of the second substrate electronic component assembly to be joined proximate to the corresponding solder structure containing pads on the first substrate;

    heating the substrates to a temperature sufficient to form a bond between the solder structure and the pads of the second substrate; and

    cooling the bonded interconnected assembly.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×