process_stencils

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
process_stencils [2022/05/23 11:24] – Updated stencil fab process. benhprocess_stencils [2024/03/03 12:48] (current) – benh
Line 7: Line 7:
 ---- ----
 ===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. 
Line 16: Line 16:
 ===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>).
 +
 +**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.) //
Line 26: Line 28:
     - 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"). 
-  - Select the "Stencil" template. (Note: I'm not sure what the "short" version is, so just use the regular one.) +  - 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.
-  - Select "Polyimide_0.125mm (non-laminated)" as the //Material type//, and "0.125mm" as the //Material thickness//. +
   - "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. Make sure it is set to the correct layers (either SolderPasteTop or SolderPasterBottom) 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". 
 +    - Stencils don't have a side because they get cut through, so by adding all the Gerbers to the same layer (i.e. SolderPasteTop), it will etch them all at once.
     - If you see a warning about nothing on a copper layer, just click "Continue".     - If you see a warning about nothing on a copper layer, just click "Continue".
   - If you have multiple solderpaste gerbers to import (i.e. multiple stencils to make, e.g. a PCB with components on both sides, or multiple PCBs), move your design out of the way (select all, right click, "Move Object"), and then repeat the previous step (the import step).    - If you have multiple solderpaste gerbers to import (i.e. multiple stencils to make, e.g. a PCB with components on both sides, or multiple PCBs), move your design out of the way (select all, right click, "Move Object"), and then repeat the previous step (the import step). 
     - After importing all your designs, move them around (left-click-and-drag to select them individually, right click, "Move Object") to position them as you'd like them to be cut.     - After importing all your designs, move them around (left-click-and-drag to select them individually, right click, "Move Object") to position them as you'd like them to be cut.
-  - "Toolpaths" > "Computer All" to computer the toolpath. Click "Close" when completed.+  - "Toolpaths" > "Computer All" to compute the toolpath.  
 +    - If it has anything other than "Contour", you've likely selected the wrong template, so go back to the start of this tutorial. Otherwise, shoot us an email. 
 +    - Click "Close" when completed.
   - Move to the "Processing" tab to position your design on the polyimide sheet.   - Move to the "Processing" tab to position your design on the polyimide sheet.
     - Turn on the pilot laser (black laser button in the toolbar).     - Turn on the pilot laser (black laser button in the toolbar).
Line 40: Line 44:
     - Move the pilot laser (double-click) to the corners of your design to confirm that the >= 1" boarder exists for all four edges. If not, you will have to either move the design again (with the "Placement" window open), or you may have to cut a larger sheet of polyimide if you mis-judged.     - Move the pilot laser (double-click) to the corners of your design to confirm that the >= 1" boarder exists for all four edges. If not, you will have to either move the design again (with the "Placement" window open), or you may have to cut a larger sheet of polyimide if you mis-judged.
   - Once the design is properly placed within the polyimide, press the green play button in the toolbar (or "Processing" > "Process All" in the main toolbar) to begin processing. Follow the steps as requested.   - Once the design is properly placed within the polyimide, press the green play button in the toolbar (or "Processing" > "Process All" in the main toolbar) to begin processing. Follow the steps as requested.
 +  - After processing, you may need to bend the stencil a bit to make sure all the little bits are out. Check with the jeweler's glass in the "PCB Tools" drawer to confirm if you can't visually confirm.
  
 ---- ----
  • process_stencils.1653319475.txt.gz
  • Last modified: 2022/05/23 11:24
  • by benh