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--- process_stencils [2022/03/01 11:29] – created benh
+++ process_stencils [2022/03/01 11:46] – benh
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 ===How to use a stencil===
-Once the stencil is fabricated, it must be aligned with the bare board underneath. The stencil should sit against the board **as flat as possible**! This is very important for applying the correct amount of paste, as well as not pushing paste underneath the stencil (rather than through the cutouts). Because the stencil is often cut out of a sheet of material larger than the PCB itself, often some unused PCB material of the same thickness (scraps or fresh, whatever you have) is used to surround the PCB and provide support to the stencil (see image below left ([[https://www.sparkfun.com/tutorials/58|source]])). Make sure to secure everything down so it doesn't move! Typically tape is used for this, but The Hive also has a fancy frame system that you can use (the [[https://www.lpkfusa.com/datasheets/prototyping/zelprint.pdf|LPKF ProtoPrint S]]). Apply paste over the stencil using whatever tool you have, either the syringe, a wooden spatula/tongue depressor, whatever. You don't need a lot, so start with less than you think you need. Then use a squeegee of some sort (credit card, ID, plastic scraper) to squeegee the applied paste across the stencil and into the cutouts (see image on right ([[https://www.pcbway.com/blog/PCB_Design_Tutorial/A_very_easy_way_to_accurately_align_the_stencil_with_the_PCB_1.html|source]])). You shouldn't need to press down very hard, and again, maintain the stencil as flat against the board as possible.
+Once the stencil is fabricated, it must be aligned with the bare board underneath. The stencil should sit against the board **as flat as possible**! This is very important for applying the correct amount of paste, as well as not pushing paste underneath the stencil (rather than through the cutouts). Because the stencil is often cut out of a sheet of material larger than the PCB itself, often some unused PCB material of the same thickness (scraps or fresh, whatever you have) is used to surround the PCB and provide support to the stencil (see image below left ([[https://www.sparkfun.com/tutorials/58|source]])). Make sure to secure everything down so it doesn't move! Typically tape is used for this, but The Hive also has a fancy frame system that you can use (the [[https://www.lpkfusa.com/datasheets/prototyping/zelprint.pdf|LPKF ProtoPrint S]]).
+Apply paste over the stencil using whatever tool you have, either a syringe, a wooden spatula/tongue depressor, whatever. You don't need a lot, so start with less than you think you need. (**NOTE!!** The reflow oven that The Hive has is optimized for **lead-free** solder paste, so if you're planning on using our oven, please make sure to use lead-free paste, or you'll be sad later.)
+Then use a squeegee of some sort (credit card, ID, plastic scraper) to squeegee the applied paste across the stencil and into the cutouts (see image on right ([[https://www.pcbway.com/blog/PCB_Design_Tutorial/A_very_easy_way_to_accurately_align_the_stencil_with_the_PCB_1.html|source]])). You shouldn't need to press down very hard, and again, maintain the stencil as flat against the board as possible.
 {{ ::stencil-usage.png?direct |}}