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| Vapour phase Soldering |
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| SeanB:
If you are wanting to recycle the fluid ( it would be good at the price) You will need to ensure that the top cold zone is as cold as possible, preferably higher than the deep fryer, and with a good source of cooling. A water jacket with a pump to circulate the water and a chiller to make it cold will work best, using an old draught chiller as the cold water source. You need to keep the board in this zone for a while after reflow, to ensure that all the liquid condenses on it and then drips down into the bottom, and keep it running after you turn the heat off till it is at room temperature and you want to dispense it back into a sealable pressure vessel to store it. Had that where I used to work, though there it was an ultrasonic cleaner using TCE, and it used the vapour phase to clean the fluid, as you could collect the drip off condensed liquid into a bucket and concentrate the dirty fluid down to a sludge for dirt removal. That would take the dirtiest castings you could find and leave them as bare clean white castings. Would strip a PCB of the resin ( except for the one conformal coat that survived no matter what) and all printed and painted parts except the copper and solder in around 3 minutes. |
| jeremy:
--- Quote from: SeanB on January 21, 2015, 07:21:39 pm ---If you are wanting to recycle the fluid ( it would be good at the price) You will need to ensure that the top cold zone is as cold as possible, preferably higher than the deep fryer, and with a good source of cooling. A water jacket with a pump to circulate the water and a chiller to make it cold will work best, using an old draught chiller as the cold water source. You need to keep the board in this zone for a while after reflow, to ensure that all the liquid condenses on it and then drips down into the bottom, and keep it running after you turn the heat off till it is at room temperature and you want to dispense it back into a sealable pressure vessel to store it. Had that where I used to work, though there it was an ultrasonic cleaner using TCE, and it used the vapour phase to clean the fluid, as you could collect the drip off condensed liquid into a bucket and concentrate the dirty fluid down to a sludge for dirt removal. That would take the dirtiest castings you could find and leave them as bare clean white castings. Would strip a PCB of the resin ( except for the one conformal coat that survived no matter what) and all printed and painted parts except the copper and solder in around 3 minutes. --- End quote --- I'm actually very strongly considering trying this. I was thinking that the best approach would be one like you are describing; basically just go really slowly with everything. I can live with more than a 6 minute cycle if it means less wasted fluid. |
| IconicPCB:
Vapour phase soldering machine from Wenesco USD5500 on their website. http://www.wenesco.com/vapor.htm A solid state diode laser source is sufficient for the task. New source and fiber under 2000 Euro new or under USD300 on ebay of questionable provenance. |
| helius:
that configuration is very widely used for a cleaning technique called vapor degreasing. they usually can be set up with two tanks and when the working tank is full of dirt, it is "boiled down" to distill the solvent into the clean tank. the solvents used for vapor degreasing are quite aggressive (high KB figures) compared to the inert fluids used for vapor soldering (should have KB at or near zero). They can sometimes cause leaching of plastic resins though, so this is something to test. in the video from 3M, they are doing selective soldering using a low melting point alloy for attaching heat sinks. So they need to use a fluid with a boiling point between the melting point of their solder (140° C) and the solder in the processor package (probably SAC305: 217° C). The Fluorinert FC-40 has a bp of 155° C, so it is perfect in this application. Galden fluids have a boiling point of 230° C because they are designed for primary soldering. |
| jeremy:
--- Quote from: helius on January 21, 2015, 09:11:08 pm ---that configuration is very widely used for a cleaning technique called vapor degreasing. they usually can be set up with two tanks and when the working tank is full of dirt, it is "boiled down" to distill the solvent into the clean tank. the solvents used for vapor degreasing are quite aggressive (high KB figures) compared to the inert fluids used for vapor soldering (should have KB at or near zero). They can sometimes cause leaching of plastic resins though, so this is something to test. in the video from 3M, they are doing selective soldering using a low melting point alloy for attaching heat sinks. So they need to use a fluid with a boiling point between the melting point of their solder (140° C) and the solder in the processor package (probably SAC305: 217° C). The Fluorinert FC-40 has a bp of 155° C, so it is perfect in this application. Galden fluids have a boiling point of 230° C because they are designed for primary soldering. --- End quote --- This is true, but you can get Fluorinert FC-70 with a boiling point of 215C. I'm thinking they designed this for the pre-RoHS era and never updated their plans. |
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