Abstract: Apparatus for use in edge etching a plurality of flat semiconductor wafers comprises a carousel releasably holding a plurality of carriers that are adapted to support a horizontal stack of wafers at selected points along the edges of the wafers. The carousel is adapted to be releasably attached to a dual axis rotary drive mechanism in a reaction chamber containing a plasma jet stream generator. The drive mechanism is operated to cause axis rotation of the carriers over the plasma jet stream, with selected edges of the wafers being directly exposed to and etched by the plasma. The etching process is interrupted to permit the carriers to be removed from the carousel for reorientation of the wafers. Thereafter, the etching process is resumed, whereby other edges of the wafers are subjected to etching by the plasma jet stream.

Abstract: This disclosure relates to a process for laser soldering surface mount components on a printed circuit board using the continuous wave laser scanning technique. The process involves factoring together the scan rate, the beam diameter, and the laser power level, in order to determine what these specific process variables should be. In addition, the process also involves taking account of the depth of a metallic layer, such as a reference plane, inside the printed circuit board to determine its effect on other process variables. On the other hand, if the board does not have a metallic layer, the process takes account of the thickness of the board being processed. Preferred ranges for process variables are identified, as well as optimization techniques which further refine the process variables to achieve production efficiency or bonding pull strength.

Abstract: This disclosure relates to laser bonding electrical components having conductive elements which are naturally reflective of the laser beam wavelength. Component leads or pads which are made of copper or have a gold coating, for example, will reflect the wavelength of an Nd:YAG laser, making it difficult to form physical and electrical bonds using the laser bonding technique. In preferred embodiments, the conductive elements are coated with a non-flux, non-metallic, coating material which is less reflective of the laser energy than the conductive elements, making it possible to efficiently use a laser to accomplish bonding.

Abstract: The present invention involves a hold-down fixture which is usable in connection with bonding an integrated circuit package to a printed circuit board in a surface mount environment. The purpose of the fixture is to hold each of the leads of the package in intimate contact with corresponding contact pads on the printed circuit board during the bonding process. The fixture includes a base with two bars for each group of leads extending from the perimeter of the housing of the package. Together the bars compressively force the entire foot of each lead to set flatly against its pad. The bars are spaced such that an aperture, which is defined by an opening through the base and positioned between the bars, can admit a bonding means, such as a laser beam, to reflow a solder composition at the lead/pad junction. Accordingly, with the leads compressed against the pads by the bars of the fixture, and with the reflow of the solder composition by means of the laser, a good bond between each lead and pad will be formed.