Copper Ball Standoff for Surface-Mounted Attachment of Mlc Substrates on Laminates
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Direct attachment of ceramic substrates onto organic printed circuit laminates is desirable for cost-performance reasons. Such attachment makes current chip carrier technology adaptable to surface-mounted applications utilizing vapor phase reflow soldering. The figure illustrates a standoff arrangement which uses all eutectic (63/37 SnPb) solder metallurgy and achieves the required standoff height with a copper ball imbedded in the solder joints. The copper ball may be pre-attached to the substrate, or deposited in the paste on the laminate before substrate placement. The copper ball can be tailored to maintain the standoff height required for joint reliability and flux cleaning. This method is applicable to any solder metallurgy, e.g., Sn, Pb, Bi, Indium, etc.