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June 4, 2006 - Updated
July 5, 2007 - Originally Posted
Several questions including specifications for hole ratio and humidity control
A few questions.
1. What is the ratio of lead to hole diameter as per the standard? Which clause of the standard is applicable?
2. What is the standard temperature and humidity in the electronic assembly storage and assembly area? How best to maintain it? What are the tolerance limits? Which clause of the standard is applicable?
3. We can not use a wrist strap where the voltage is more than 80 VAC. Why? What are the technical reasons behind it?
4. What are the precautions to be taken while applying a peelable mask?
Thanks for your expert advice.
Veerendra Kumar Singh
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| Expert Panel Responses |
I'll take the first one. Reference DOD-STD-2000, Volume 2A, 5.1.1.2.1 - 5.1.1.2.4 Round leads Maximum clearance, 0.028"/0.7mm Minimum clearance, 0.010"/0.25mm (of the maximum Lead Diameter) Rectangular lead Maximum clearance, 0.028"/0.7mm Minimum clearance, 0.006"/0.15mm (of the maximum diagonal/cross section of the lead)
Mel Parrish
FSO/Director Training Resources, STI Electronics Inc.
Mel Parrish is the FSO and Director of Training Materials Operations, Soldering Technology International (STI), in Madison Alabama. Before coming to the STI, Mel was the Training Manager for the Electronic Manufacturing Productivity Facility (EMPF) and President of Manufacturing Technology Training Center Inc. (MTTC) in Ridgecrest, CA. He remains active in industry trade associations and organizations such as IPC, SMTA, and SME.
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