Electronics > Projects, Designs, and Technical Stuff
Vapour phase Soldering
hkBattousai:
I have been searching "vapour phase soldering" in Google for more than an hour, but I still haven't found answer to one question:
At what step is the solder put onto the PCB?
I watched many Youtube videos (there wasn't any close up one). They put the PCB solderless PCB inside the hot cloud. And when they take it back, there are solders on the pads. Where did that solder come from? The boiling liquid doesn't contain any solder as far as I understood.
Can you please clarify this?
MK:
--- Quote from: hkBattousai on March 07, 2015, 12:43:46 pm ---I have been searching "vapour phase soldering" in Google for more than an hour, but I still haven't found answer to one question:
At what step is the solder put onto the PCB?
I watched many Youtube videos (there wasn't any close up one). They put the PCB solderless PCB inside the hot cloud. And when they take it back, there are solders on the pads. Where did that solder come from? The boiling liquid doesn't contain any solder as far as I understood.
Can you please clarify this?
--- End quote ---
They use solder paste, when it reaches the melting point the components stick with the surface tension of the solder.
hkBattousai:
--- Quote from: MK on March 07, 2015, 06:01:48 pm ---
--- Quote from: hkBattousai on March 07, 2015, 12:43:46 pm ---I have been searching "vapour phase soldering" in Google for more than an hour, but I still haven't found answer to one question:
At what step is the solder put onto the PCB?
I watched many Youtube videos (there wasn't any close up one). They put the PCB solderless PCB inside the hot cloud. And when they take it back, there are solders on the pads. Where did that solder come from? The boiling liquid doesn't contain any solder as far as I understood.
Can you please clarify this?
--- End quote ---
They use solder paste, when it reaches the melting point the components stick with the surface tension of the solder.
--- End quote ---
Thanks MK. I always though that "solder paste" is just another name for "flux". I made a quick research and learned about it.
helius:
hkBattousai: the solder paste appears as a matte gray substance, but under high magnification it contains many small balls of solid solder in a flux gel. at the instant it reflows, it turns shiny and bright. Since it is sticky before reflow, it is used to stick components down to their pads before the board is moved to the reflow machine.
You can see the tiny solder balls melting together in this video:
Watch at 1:00 and 1:40
jeremy: the data sheet that comes with the HT230 in your picture shows a BP range of 222-237 C (10-90%). That seems to be quite close to a previous poster's figures for LS230:
--- Quote from: mrpackethead ---Some more data, that i was able to obtain tells me that;
The Distillation spec range of the HT230.
10% > 210C, 90% < 250
Compared to the LS which is
10% < 222, 90% < 235
--- End quote ---
Is there an error somewhere?
Edited: I see that the first figures are for the specific batch you received. So it looks like your batch is within the same range as the worst-case spec for LS230, implying it may work perfectly fine in machines designed for LS230.
Chris Jones:
Hi all,
I've just started using an Asscon Quicky 300 (stop sniggering) vapour phase reflow soldering machine at work, with HT-230 Galden and lead-free solder paste. It worked pretty well on my first try though my stencil might be a little thick (thickest option from OSHstencils) - I got some solder bridging on a 0.5mm pitch LQFP so I needed to rework that with some solder braid, but very happy for a first try as it saved me about two days worth of hand soldering on that board.
I have the manual for the machine (on paper only at present), and I have recorded some temperature profiles at a couple of places in the chamber. It is an interesting machine. The top glass door has a seal around it which is pressed tightly by a clamp to stop vapour getting out - I had a thermocouple wire going over the seal and a bit of Galden leaked out there due to the wire preventing a good seal in that location. The board carrier stays put down near the bottom of the tank a few centimetres above the fluid surface, during the heating and cooling periods (~ 2.4kW flat heater plate UNDER the base of the tank). The tank holds 1kg of Galden. The vapour rises in the chamber and when it gets to the board, the board heats very rapidly. You can see the solder melt, then once the board reached the top temperature (229C) I gave it another 20 seconds and pressed the button to stop the cycle (trying not to cook the chips for too long) at which point it dumps cooling water through a stainless steel pipe that is immersed in the fluid tank at the bottom of the chamber, and now-hot water from this pipe drains out through a pipe from the bottom of the machine. The water-cooled stainless pipe quickly starts re-condensing the vapour and the board cools down fairly rapidly. When the board gets back down to about 150C you can wind the board up to the top of the chamber to dry off and cool a bit more. If you don't press the button to stop the cycle when the solder has melted, then the vapour keeps rising in the chamber until it gets to a temperature sensor about half-way up the front wall of the chamber which terminates the cycle. That would result in the board down the bottom of the tank being at 230C for about 3 minutes which was longer than necessary so I used the stop button instead of waiting for the vapour to reach the sensor.
If anyone wants more info on this machine let me know. I would like something like this for home too, though then I'd probably need to buy some Galden of one of you.
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