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Method of Determining If Cracks in Ceramic Exist After Brazing or Soldering, When Covered by Metallic Film

IP.com Disclosure Number: IPCOM000060384D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

King, WJ: AUTHOR

Abstract

A processing step in the production of semiconductors involves an I/O pin attachment and pull test. Cracking of the ceramic substrate may occur during the test which, if undetected, can result in reliability problems with the completed device. An invention proposes a method of exposing the entire pad/ceramic interface for examination so as to detect any cracks. During testing of pin joints on glass or ceramic modules the criteria for a successful bond is fracture in the braze or solder, or, preferably, in the shank of the pin. Cross-sections of joints which have had all shank fails on the pin sometimes show cracks in the ceramic. This cracking can also be identified on pin brazes which have not been tested.

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Method of Determining If Cracks in Ceramic Exist After Brazing or Soldering, When Covered by Metallic Film

A processing step in the production of semiconductors involves an I/O pin attachment and pull test. Cracking of the ceramic substrate may occur during the test which, if undetected, can result in reliability problems with the completed device. An invention proposes a method of exposing the entire pad/ceramic interface for examination so as to detect any cracks. During testing of pin joints on glass or ceramic modules the criteria for a successful bond is fracture in the braze or solder, or, preferably, in the shank of the pin. Cross-sections of joints which have had all shank fails on the pin sometimes show cracks in the ceramic. This cracking can also be identified on pin brazes which have not been tested. Conventional inspection methods include exposure of the substrate surface by use of metallographic and fluorescein dye techniques. This is a time-consuming approach and only exposes single planes or small areas. The invention proposes a process for lot screening. The pin metallurgy is removed by dissolving the layers with successive chemical solutions. Referring to Fig. 1, a slightly diluted aqua regia is used to completely dissolve the top surface alloy pin 1 with Pd 2 and Au 3 plating, the Au/Sn braze 4, the top layer of Ti 5 and the layer of Cu 6. The Ti 7 left on the ceramic substrate 9 is then removed with NaOH H2O2 or H2SO4 . If cracks 8 exist they...