Solder Paste Volume Calculator: Paste per Board and per Run
Solder paste is a small cost per board, but running out mid-lot or scrapping expired jars hurts. This calculator turns your stencil data into grams per board and jars per run so purchasing and the line agree on the number.
Your numbers
Count from the stencil Gerber or the paste layer report.
Total aperture area divided by count.
100 to 130 micron is common for mixed technology.
Share of aperture volume that actually prints.
Typical SAC paste is around 3.8 to 4.2; check the datasheet.
Stencil wipes, setup, paste left on blades and expired remnants.
Your results
Planning estimate. Measure actual consumption over several runs and adjust the waste allowance.
Jars required vs transfer efficiency
Sweeps Transfer efficiency from 50 to 100, holding your other inputs fixed.
Track paste lots against work orders
An optional review of lot, expiry and usage tracking for consumables in your ERP.
Optional. The tool and every export work without this. No spam.
How to use it
Pull the aperture count and total aperture area from your CAM or stencil vendor report, then divide area by count for the average. Enter stencil thickness, the transfer efficiency you see in practice, the paste density from the datasheet, the run size and your waste allowance. The tool reports the deposited volume per board, grams per board, total jars and cost. The slider chart shows how sensitive consumption is to transfer efficiency.
- Use SPI average volume to calibrate transfer efficiency
- Include the first-article and setup boards in the waste allowance
- Count jars opened, not just grams printed
The math
Deposited volume per board equals aperture count times average area times stencil thickness times transfer efficiency. Mass equals volume in cubic centimetres times paste density, because 1000 cubic millimetres make one cubic centimetre. Note that paste is roughly half metal by volume, so the density figure should be for the paste as supplied, not the alloy. Waste is applied as a percentage on top, then rounded up to whole jars.
Common mistakes
People often use alloy density instead of paste density, which overstates mass by a wide margin. Others forget step stencils or multiple thicknesses, where you should calculate each zone separately and add them. Paste on the stencil also ages, so a long idle period can force a discard of the working roll. Finally, remember shelf life and thaw time: planning jars correctly is useless if the stock is expired when the lot starts.
Frequently Asked Questions
How much solder paste does one PCB use?
It depends on aperture area and stencil thickness. A moderately dense board may deposit a few tenths of a gram to a few grams. Use your own aperture data in the calculator, since pad count varies enormously between designs.
What is a normal transfer efficiency?
Well-designed apertures with an area ratio above about 0.66 often transfer 80 to 95 percent, while small or poorly designed apertures can fall well below that. Your SPI data is the best source for the real number.
Why include a waste allowance?
Paste is lost to setup prints, stencil wipes, paste left on the squeegees or stencil at changeover, and partly used jars that exceed their open life. A 15 to 30 percent allowance is a common starting range until you measure.
Do I need to account for paste density?
Yes, to convert volume to mass. Take the density from the paste supplier datasheet for the specific alloy and flux percentage. Using a generic value is fine for planning but verify before large purchase orders.
Netray can connect paste consumption to your ERP work orders and lot records so usage and expiry are visible per job, not estimated.
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