In SMT Stencil Print Processes is Transfer Efficiency or Transfer Effectiveness More Important?
We often get asked what the difference between transfer efficiency and transfer effectiveness in SMT stencil print processes is? In this technical bulletin we will cover this important topic in addition to detailing how NanoClear SMT stencil nano-coating will improve your printing.
Technical Bulletin Series
What is the difference between Transfer Efficiency and Transfer Effectiveness?
- Transfer Efficiency: The total volume of solder released from an aperture, expressed as a %
A measurable, quantitative metric
- Transfer Effectiveness: The quality of the deposit shape and the variation in volumes
A qualititative characteristic that affects yields and reliability
More paste is not always better!
If a µBGA or 0201 typically runs with 400 mils³ of solder paste on its I/O pads and gets a 25% volume increase, 500 mils³ of paste can cause shorts, solder balls, tombstones or excessive skewing, all of which require rework.
On Miniature Devices more paste can cause lower yields.
Production 0.4mm QFN (100µm stencil)
Before Coating
- Excessive paste volumes
- Higher volume variation
- Poor shape quality
- High risk of solder defects
After NanoClear
- Proper paste volumes
- Less volume variation
- Good shape quality
- Low risk of solder defects
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