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INNOVATION IN WAVESOLDERING

IP.com Disclosure Number: IPCOM000009409D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-21
Document File: 2 page(s) / 113K

Publishing Venue

Motorola

Related People

Charlie D. Feagin, Jr.: AUTHOR

Abstract

This paper describes an improvement to the in- line wavesolder method used to solder leads to ceramic printed circuit substrates. Specifically, the substrates are conveyed through the process via a tractor driven common carrier strip with attached leads on which they arc pre-inserted.

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MOmOLA Technical Developments

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INNOVATION IN WAVESOLDERING

by Charlie D. Feagin, Jr.

INTRODUCTION

  This paper describes an improvement to the in- line wavesolder method used to solder leads to ceramic printed circuit substrates. Specifically, the substrates are conveyed through the process via a tractor driven common carrier strip with attached leads on which they arc pre-inserted.

PROBLEMS TO BE SOLVED

  Since the carrier strip is laidened with the enor- mous weight of hundreds of populated ceramic sub- strates, it must be drawn with a tractor type motor- ized drive gear. The drive gear's teeth mate with the carrier strip's holes. Therefore, the drive holes must be clear of solder before it solidifies and reaches the drive gear. In addition, the leads' eyelets must also be clear of solder to allow the substrate to be mount- ed properly into its housing. However, the old method of accomplishing that task markedly increased the amount of airborne solder balls. Each flying ball of solder has the potential of impacting the circuit, and causing an electrical short or compo- nent damage. The old method can be described as simply mounting short tube brushes in contact with the carrier strip and lead eyelets. The bmshes' bris- tles would fling hundreds of solder droplets in the air, in every direction. The old method was also inefficient, in constant need of adjustment during operation, and very unsafe. These brushes often missed solder filled eyelets and drive holes. As a result, severe mechanical jams frequently took place. Solder filled eyelets and drive holes generat- ed a considerable amount of rework. It required that any tilled lead eyelets found at the next operation be cleared manually.

SOLUTION TO THE PROBLEMS

  The solution materialized as a semi-enclosed angled parallel dual brush assembly. Its features and their benefits are as follows: (refer to the picture on next page)

  Enclosure: semi-encloses the dual brushes to deflect airborne solder-balls downward and away from substrates. Open at the bottom, front and back to dissipate heat and prevent solder buil...