Chip Replacement Unit
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
With costly multi-chip electronic modules, it is highly desirable to have the ability of reworking them, say, to remove a chip. e.g., a defective one, and to replace it by a good one or an updated one. The removal of the chip is effected by applying heat to the solder columns which bond the chip solder pads to the metallization pattern deposited onto the surface of the ceramic substrate according to standard techniques. A key problem is the dressing or cleaning of the solder pads remaining based on the absorption by capillary forces of the molten solder in a chip shaped porous copper block. After dressing, a new chip is bonded. The three basic operations (removal of the chip, dressing, and placement of a new chip) may be done in a single unit which is schematically depicted in Figs. 1A and 1B.