| General > General Technical Chat |
| Hand placing large boards |
| (1/1) |
| ezalys:
Let’s suppose I have a board with several hundred or so components on it and I only want one. I’m somewhat afraid of the paste drying before I finish hand placing. I’m also afraid of rushing and screwing up the placement. What’s the professional solution to this problem outside of programming a pick and place? |
| m98:
A manual PNP machine would be the way to go here. Also, there are pastes that don't dry out for days, Felder LPT3C-0100LF, for example. |
| ezalys:
Do you have a recommended manual PNP? |
| winniethepooh_icu:
Do not be so intimidated by hand placement. You can easily place 100 passive parts in an hour, even 0402 parts. If many components are the same you can approach 200 per hour with ease. The time to set up and manually place with a manual PNP will be large compared to the time to hand place even with some mistakes. Place the board on a flat surface, tape down if it helps. Place a small amount of solder on one pad of each device footprint, always on the side that your hand is holding your iron, and place with tweezers and your other hand. First center the device with tweezers on the footprint, light pressure, then bring in your iron and let it sink into the soldered pad. Wipe iron up over the edge of the device if you think it isn't sticking. If you placed it at a bad angle, reposition your tweezers, heat the pad and move it. If you must re-position a ceramic capacitor, take care not to put force on it while squeezing with the tweezers as you may break it in half, but this is easy to deal with even if it happens. If you have QFN parts, spend more time aligning with a bright light on the side than you spend soldering them. Do not put solder on a QFN pad before placing it, these are placed first and soldered after careful alignment and holding down with the tip of the tweezers. Applying flux first will help with first pins that are soldered with a bit of solder already present on the tip of your iron. A good pair of tweezers and learning to apply the right amount of pressure will be faster than a manual PNP even with a large board. Problems are easy to fix if you solder one side of each device first. |
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