Preventing whiskers in electrodeposited tin for semiconductor lead frame applications
A new pure tin process is described which produces a deposit with a crystal orientation combination that minimises whisker growth, particularly when used with a specific pre-treatment process. A recommended etch depth of minimum 2.5 μm has been shown to reduce whisker growth, particularly with thin...
Saved in:
Published in | Circuit world Vol. 30; no. 2; pp. 20 - 24 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bradford
Emerald Group Publishing Limited
01.06.2004
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | A new pure tin process is described which produces a deposit with a crystal orientation combination that minimises whisker growth, particularly when used with a specific pre-treatment process. A recommended etch depth of minimum 2.5 μm has been shown to reduce whisker growth, particularly with thin (3 μm) tin coatings. Crystal orientation is determined by X-ray diffraction and the angles between adjacent crystal planes are calculated from the pattern produced. A minimum proportion of small angles is required for lowest whisker risk. Angles smaller than 22° have been shown to be critical. The predominant orientations of the deposits from new tin process are 101, 211, 112, and 312. This combination of orientations has 8 percent of angles in the critical range. A typical pure tin process with a high tendency for whiskering may have a texture of 431, 321, and 211 orientations, and this combination produces 65 percent of angles smaller than 22°. |
---|---|
Bibliography: | original-pdf:2170300202.pdf ark:/67375/4W2-ZX7NVN9J-L istex:3DB28C41035AED31507826ADB1E63EE4F82B85EE href:03056120410512118.pdf filenameID:2170300202 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0305-6120 1758-602X 0305-6120 |
DOI: | 10.1108/03056120410512118 |