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Measuring the Tin Lead Ratio in Plated Solder

IP.com Disclosure Number: IPCOM000092297D
Original Publication Date: 1968-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Krouse, DR: AUTHOR

Abstract

This method provides an accurate, rapid, and nondestructive measurement of solder composition regardless of the surface condition of the sample, for example one having corrosion films. A duo-source beta backscatter gauge is used for the measurement. The method consists of making two beta backscattering measurements using two radioactive sources S1 and S2 emitting different maximum energy beta particles, electrons. The sample to be measured is placed in a sample slot of a rotatable source holder which exposes the sample to source S1. Then the backscattered effect is picked up by a detector connected to a counter and high-voltage supply. After noting the backscattered count measurement as the result of exposure to source S1, the source holder is rotated to expose the sample to the effects of source S2.

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Measuring the Tin Lead Ratio in Plated Solder

This method provides an accurate, rapid, and nondestructive measurement of solder composition regardless of the surface condition of the sample, for example one having corrosion films. A duo-source beta backscatter gauge is used for the measurement. The method consists of making two beta backscattering measurements using two radioactive sources S1 and S2 emitting different maximum energy beta particles, electrons. The sample to be measured is placed in a sample slot of a rotatable source holder which exposes the sample to source S1. Then the backscattered effect is picked up by a detector connected to a counter and high-voltage supply. After noting the backscattered count measurement as the result of exposure to source S1, the source holder is rotated to expose the sample to the effects of source S2. The backscattered count measurement is noted of the second activity.

The relative saturation backscatter intensity is a linear function of the effective atomic number of the scatterer. For plated solder consisting of 50 percent tin, Z=50, and 50 percent lead, Z=82, the effective atomic number is 66 and the materials should backscatter beta particles with the same intensity as the backscatter from dysprosium, Z=66.

From an uncorroded sample, the relative backscattering is the same for two different sources. The relative backscattering, however, is not the same if the surface is corroded. The difference can be attributed to...