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Bevel-Shaped Through-Hole Mount Solder Fillet

IP.com Disclosure Number: IPCOM000022663D
Publication Date: 2004-Mar-24
Document File: 2 page(s) / 86K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that creates a bevel-shaped opening on the through hole at the bottom of a PCB. Benefits include improving wave fluxing efficiency and wave solder penetration into the through hole.

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Bevel-Shaped Through-Hole Mount Solder Fillet

Disclosed is a method that creates a bevel-shaped opening on the through hole at the bottom of a PCB. Benefits include improving wave fluxing efficiency and wave solder penetration into the through hole.

Background

IPC standards require a minimum wave solder fill percentage of 75% or higher; however low wave solder fill percentages are common, and cause severe degradation in the wave soldering pin’s mechanical strength. In addition, it can cause premature electrical open failures, field failures of through hole mount components and the detachment of retention pins.

A low wave solder fill percentage can be caused by:

§         Insufficient wave fluxing, where insufficient wave solder flux is spread into the through hole sidewall and the pins to effectively remove surface oxide for wave solder adhesion.

§         Insufficient contact time when the bottom surface of the PCB touches the wave solder bath.

§         Insufficient heating during preheat or at the wave solder bath.

Currently, the failures are resolved by:

§         Increasing the wave solder fluxing by increasing the fluxing spraying pressure and by changing from jet fluxing to spray fluxing

§         Prolonging the contact time in the wave solder bath by reducing the conveyor belt speed.

§         Utilizing chip waves to enhance the wave solder penetration into the though hole, then following the Lambda wave to form the bottom outer fillet.

§         Increasing the preheat and wave solder bath temperatures. (However,...