Westinghouse Electric Corporation

Corey H Bowcutt

James A Rew

John J Buckley

Michael J Ankrom

A method for vapor phase soldering components onto a PWB onto which solder has been previously deposited includes the steps of applying a fluxing agent on the PWB and introducing the PWB into a vapor phase environment. The application of flux is a multi-step process which includes a sequential application of flux to the PWB. The vapor phase environment defines a temperature gradient between approximately ambient and the temperature of a saturated vapor of a first selected fluid which defines a primary saturated vapor phase with a boiling point which is greater than the melting point of solder. A second fluid having a boiling point which is lower than the first fluid is utilized to generate a secondary vapor blanket in order to prevent excessive loss of the fluid defining the primary vapor phase. The PWB is heated according to a controlled process in which the temperature of the PWB is continuously monitored.

Method for vapor phase soldering

An apparatus for printed wiring board assembly provides for the populating with components of a printed wiring board having at least one adjacent pair of pad rows onto which solder has been deposited. A curable adhesive strip is applied between the adjacent pair of pad rows. The adhesive strip has a first adhesive side which adheres to the printed wiring board and an opposed, second adhesive side onto which the components are selectively mounted so that the component's leads are aligned with the pad rows. A predetermined constant force is applied to the components and the adhesive strip is cured. The apparatus supports the printed wiring board and maintains a predetermined constant force on the components. A frame defining a generally U-shaped member has an upper and a lower surface. The U-shaped member has a slot therein for receiving the printed wiring board therein. An upper and a lower cover member are removably secured to the U-shaped member to generally enclose the printed wiring board. Resilient biasing is disposed between the printed wiring board and the cover members, whereby a predetermined constant force is maintained on the mounted components.

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Annapolis, MD, United States of America

Corey H Bowcutt