National Semiconductor Corporation

Fairchild Semiconductor Corporation

Richard C Wood

Roger H Doherty

Apparatus (10) and method for solder finishing the leads of an integrated circuit package are applicable to 'flat packs' or flat packages having coplanar rows of leads (84) along sides of the flat package (75). First and second tracks (22,26) are formed with elongate first and second supporting surfaces (72,74) oriented with the first and second supporting surfaces at opposite first and second downwardly depending angles (.THETA.1,.THETA.2). First and second index edges (70) are formed along the respective first and second supporting surfaces of the first and second tracks (22,26) for retaining a flat package (75) at the respective opposite first and second downwardly depending angles. Vertical first and second falling columns of molten solder are established at first and second loci of solder finishing (16a,16b) defined by solder bridge sections (66,68) with the first and second falling columns (85) located on the lower sides of the respective first and second tracks (22,26). A conveyor line (44) formed with pushers (76) pushes the flat package on the respective first and second tracks (22,26) along first and second transport paths (25,28) with respective downwardly depending first and second rows of leads (84) passing through the respective first and second tilting mechanism (100) at the transfer end of the track section lifts the flat package from the first track (22), reorients the flat package from the first downwardly depending angle (.THETA.1) to the second downwardly depending angle (.THETA.2) and deposits the flat package (75) on the second track (26).

Solder finishing planar leaded flat package integrated circuit leads

A new method for solder finishing the leads of an integrated circuit package such as a DIP having two parallel rows of leads along the sides of the package. The method contemplates establishing two vertical columns of falling molten solder and spacing the columns apart a distance substantially the width of the package. The package is passed between the vertical columns of falling molten solder immersing the two parallel rows of leads along the sides of the package in the respective columns of molten solder, washing the leads and depositing a finishing layer of solder over the surfaces of the leads. The method further contemplates directing hot nonreacting gas over the leads of the package as the package passes from the columns thereby eliminating excess solder and bridging of solder between the leads. A monorail track system and a new solder bridge for implementing the method are described. The invention may be applied for column fluxing as well as for other column liquid treatments.

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Portland, ME, United States of America

Richard C Wood