process_stencils

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process_stencils [2022/05/23 13:00] – benhprocess_stencils [2024/03/03 12:48] (current) – benh
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 ===What is a stencil?=== ===What is a stencil?===
-A //stencil// is a material with cutouts that enables solderpaste to be more easily and precisely applied prior to component placement and reflow. (If you don't know what I mean by 'reflow', or want more information about that process, see our "[[process_reflowOven|Reflow Oven]]" page for more.) Stencils can be made with a variety of materials; the images below show two very common ones (polyimide on the left, and stainless steel on the right) ([[https://www.autodesk.com/products/eagle/blog/getting-started-solder-paste-stencils/|Source for images]]). Kapton tape (also polyimide) is another low-cost option. The Hive has 5mil polyimide sheets for stencil fabrication that are free for users, as well as Kapton tape.+A //stencil// is a material with cutouts that enables solderpaste to be more easily and precisely applied prior to component placement and reflow. (If you don't know what I mean by 'reflow', or want more information about that process, see our "[[process_reflowOven|Reflow Oven]]" page for more.) Stencils can be made with a variety of materials; the images below show two very common ones (polyimide on the left, and stainless steel on the right) ([[https://www.autodesk.com/products/eagle/blog/getting-started-solder-paste-stencils/|Source for images]]). Kapton tape (also polyimide) is another low-cost option. The Hive has 5mil polyimide sheets for stencil fabrication that are free for users, as well as Kapton tape. We also have (courtesy of Stephan Strassle) recipes for using [[https://www.amazon.com/dp/B087BF4YLJ?ref=ppx_pop_mob_ap_share|PET projector transparency sheets]] between 0.5 and 10 mil thick.
  
 Stencils are by no means a required or necessary step for completing your PCB. They are very useful if you have many surface-mounted components (SMDs), SMDs with many pins or fine-pitch pins, or have a few SMDs but many identical boards. //They do not work for through-hole components!// Those must be done by hand.  Stencils are by no means a required or necessary step for completing your PCB. They are very useful if you have many surface-mounted components (SMDs), SMDs with many pins or fine-pitch pins, or have a few SMDs but many identical boards. //They do not work for through-hole components!// Those must be done by hand. 
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 ===How to make a stencil=== ===How to make a stencil===
 Stencils can be fabricated at The Hive using the LPKF ProtoLaser U4. The process detailed here is for //**5 mil/0.125mm polyimide ONLY**//. The Hive provides this material free of charge to our users. For other //accepted// materials, you'll have to adapt the process below. **Stainless steel is not allowed in the ProtoLaser!!** If you require a stainless steel stencil, please email us (<hive-pcb@ece.gatech.edu>). Stencils can be fabricated at The Hive using the LPKF ProtoLaser U4. The process detailed here is for //**5 mil/0.125mm polyimide ONLY**//. The Hive provides this material free of charge to our users. For other //accepted// materials, you'll have to adapt the process below. **Stainless steel is not allowed in the ProtoLaser!!** If you require a stainless steel stencil, please email us (<hive-pcb@ece.gatech.edu>).
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 +**NOTE:** If you're using the PET sheets ([[https://www.amazon.com/dp/B087BF4YLJ?ref=ppx_pop_mob_ap_share|Amazon link]]), the material settings should be labeled "PET_<thickness>um" (there might be an "ss" in there somewhere as well, for the creator) for whatever thickness in um (microns, NOT mils) you're using. The process below will be the same other that the material settings selection.
  
 //(If you have never used the ProtoLaser before, you'll need to be trained prior to use; see [[pcb-training|this page]] for details on that. Stencils made of non-metallic materials, like polyimide, can also be made with our laser cutters, but that's beyond the scope of this write-up.) // //(If you have never used the ProtoLaser before, you'll need to be trained prior to use; see [[pcb-training|this page]] for details on that. Stencils made of non-metallic materials, like polyimide, can also be made with our laser cutters, but that's beyond the scope of this write-up.) //
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     - It's advisable to tape it down as snug as possible. Unlike FR4, this will flap around during processing if it's not secured to the table. Taping all four edges works well.     - It's advisable to tape it down as snug as possible. Unlike FR4, this will flap around during processing if it's not secured to the table. Taping all four edges works well.
   - Start a new project ("File" > "New").    - Start a new project ("File" > "New"). 
-  - Click "Browse" (lower left) and navigate to the Desktop. Select the stencil file (.cp2d), which should have a title like, "THE-HIVE_Stencil.cp2d", maybe with some additional information like "polyimide" and/or a thickness.+  - The template is called "THE-HIVE_Stencil" or something similar. It should be in the templates list at the top under "Custom Templates", but if it is not, click "Browse" (lower left) and navigate to "Documents". The stencil file should be there.
   - "File" > "Import", and select a solderpaste gerber file.    - "File" > "Import", and select a solderpaste gerber file. 
     - Note that you need one stencil per side of the board, so only select a single gerber file. Put the Gerber onto the SolderPasteTop layer even if the gerber should be for the bottom solder paste, before clicking "OK".     - Note that you need one stencil per side of the board, so only select a single gerber file. Put the Gerber onto the SolderPasteTop layer even if the gerber should be for the bottom solder paste, before clicking "OK".
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  • Last modified: 2022/05/23 13:00
  • by benh