The principle cause of crack defects in optoelectronic materials with phosphorus-containing underlayer

Abstract

The principle cause of cracks in laser-welded, Au-coated, optoelectronic materials with a phosphorus (P)-containing underlayer is studied experimentally and numerically modeled. Experimental results find that the crack formation is due to the existence of a P-containing underlayer and is not due to the thickness of the Au plating layer. The P-containing underlayer introduced by a electroless plating process may generate a low melting, P-rich segregation layer during solidification. A finite-element method analysis is performed to evaluate the residual stresses variation of the low melting P-rich segregation layer. Results show that the high residual tensile stresses of the P-rich segregation layer are generated by solidification shrinkage. A crack may be initiated by this residual stress. Both experimental observations and numerical calculations indicate that the crack formation mechanism in laser-welded Au-coated optoelectronic materials is directly related to the low melting P-rich segregation layer and its associated high tensile stresses. Based on these results, a Ni underlayer with Pfree electroplating, instead of P-containing electroless plating, should be used prior to plating Au on optoelectronic materials to prevent crack formation in laser welded Au-coated optoelectronic materials.

Active fiber-solder-ferrule alignment method for high-performance opto-electronic device packaging

“…This difference causes an offset error. If an included angle exists between the CCD and the fiber, the magnitude of the offset error is calculated as (5) where denotes the offset error; represents the fiber distance out of the ferrule; and is the angle included between the CCD and the fiber.…”

“…In FSF assembly, an optical fiber with a metallized end is soldered in a ferrule tube, and the FSF is Manuscript joined on a -channel mounted in front of the laser diode by laser welding [3]- [5]. Regardless of the location of the fiber in the ferrule tube, the location of maximum coupling power can be dynamically measured and the FSF then soldered to maintain this maximum coupling power.…”