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| process_stencils [2022/03/01 11:46] – benh | process_stencils [2022/03/01 12:24] – benh |
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| **NOTE!!** The human eye is very good at detecting mismatched edges! However, this process is surprisingly tolerant, especially with regular-pitch components. Try not to be too picky. You can also always reflow again, or cut traces later if needed. It's a bit of trial and error to get a feel for this. | **NOTE!!** The human eye is very good at detecting mismatched edges! However, this process is surprisingly tolerant, especially with regular-pitch components. Try not to be too picky. You can also always reflow again, or cut traces later if needed. It's a bit of trial and error to get a feel for this. |
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| | One other thing to note about this process is that it's extremely likely that it will look like the pads are shorted together, i.e. the paste will connect across pads. This is typically okay! When the paste melts, it will naturally wick to the nearby copper, which is hotter than the soldermask and/or the bare FR4. **BE AWARE!!** If you have a bare board, i.e. without soldermask, it's critical to etch copper away from between the pads, or you //**will**// get shorted pads later. This must be done prior to board fabrication. (Soldermasking can be attempted with Kapton tape, but YMMV and it's a very unsupported process. See [[process_kaptonMask|this page]] for how you can try that.) |
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| After the paste is applied to your satisfaction, move your board and all the components for placement to near where the reflow will happen (either a bench with a reflow station if you're a masochist, or near the reflow oven in the semi-clean room). You want to do the actual placement of components near to where the reflow will happen because the less you need to move the board with all your non-soldered-on components, the better. Using tweezers (we have plenty upstairs), place each component onto the PCB in the proper position. Double check the component //and orientation// prior to placement! You'll be sad later if you discover you put a key IC on backwards and fried it. Pin 1 is often indicated with a dot. | After the paste is applied to your satisfaction, move your board and all the components for placement to near where the reflow will happen (either a bench with a reflow station if you're a masochist, or near the reflow oven in the semi-clean room). You want to do the actual placement of components near to where the reflow will happen because the less you need to move the board with all your non-soldered-on components, the better. Using tweezers (we have plenty upstairs), place each component onto the PCB in the proper position. Double check the component //and orientation// prior to placement! You'll be sad later if you discover you put a key IC on backwards and fried it. Pin 1 is often indicated with a dot. |