Solar Freaks

Reflow Soldering is a process in which all the components on a pcb are placed into position, with only a very thick paste (solder paste), holding them from moving or falling out of place.

After all the components are placed into position, the board is passed through a temperature controlled oven, and the solder paste melts forming a normal solder joint. this process is usually automated, and it is the technique they use to populate mobile phone, and computer mother board PCB's.

The solder paste is ONLY allied to PCB contacts, and then the components are placed into correct position.
Reflow can be achieved by heating the paste with hot air, or also by infra-red heating. Infra-red is usually preffered as it is better controlled.

THAT'S CHEATING!

hello,

I am currently looking for the critical parameters concerning reflow soldering, I know about increase temperature for pre-heating, time of reflow, but what about cooling time? and maybe soldering material preparation or conservation??

thank you

Typical temperature profile is attached.

Hi

One of the most famous standard for soldering is J-STD-020C (available in internet as PDF). According to that, cooling gradient can be max. 6°C/s (Table 5-2).

Edit: As reference, below I attached a typical reflow soldering profile of smart gate driver optocoupler ACPL-332J.




Regards
Hakan

Hi All,

I would like to try a doing some reflow solering in a toaster oven but am not sure what is the best brand or type of solder paste to use.

Has anyone tried this and if so what kind of paste did you use and where did you get it?

From what I have read it is possible to get a real proffesional looking finish using the reflow method and the oven. Would be awesome to watch the solder melting and all the components aligning themselves

Regards,

Paul.

This is the stuff i use http://au.farnell.com/149976/tools/product.us0?sku=multicore-solder-sn62ra10bas86-25g-cartridge

Its really good, low melting point 189degrees and should work well with a toaster , however i just use a hot air soldering gun.

Reflow is really great and leaves a clean surface, and the flux completely evaporates, and doesnt leave the brown residue like normal normal solder.

what i do is first heat up the boards to around 80-90degrees, apply paste to all the pads, place the parts, then slowly heat it to around 250degrees for reflow.

gives a perfect finish. looks like a robot did it.

Thanks for the reply SolarOne.

I have ordered a tube of the paste and cant wait to give this a go. I am currently designing my first board using Eagle and should be done in a few days. I will order a few spares as I am sure that there could be a few mistakes to start with.

Thanks for your help.


paul.

Hi Paul how did you go with the solderpaste and toaster?

Post some pictures up so we can your quality.

This one is good for tricky applications because the needle is very sharp, however you get less of it.
http://au.farnell.com/876768/tools/prod ... edsyn-cr44

And here is the lead free version: http://au.farnell.com/1521898/tools/pro ... dsyn-cr-88
Its always good to stick to the safe side.

I think I have pushed reflow soldering to new levels of dodgyness.

I ended up getting the paste on Friday arvo and had to give it a go. I had a couple of break out boards for an as5040 and a heap of spare chips. Time to give it a go.

I dont have a toaster oven yet so I though I would try the convection/microwave oven. On oven mode

I preheated the oven to 150 degrees C, put a little paste on the board(a real small amount), placed the chip on and then threw her in the oven. I let it sit at 150 degrees for 120 seconds and then ramped the heat up to 190 degrees for another 120 seconds. At about the 60 second mark the solder started to melt. I gave the oven a bit of a tap to try to get the chip to align itself. All looked good through the glass.

I took the board out of the oven and let it cool. It looked great apart from 2 of the pins being bridged. A bit of wicking had that sorted. I am not sure of the quality of the solder joins but the finished product looked really good.

Connected it up to the micro and the AS5040 was working fine. Amazing how they still work after being in an oven.

I reckon that this process would be alot better in a small toaster oven. Heat control would be better and it would be alot easier to see what is going on. Can't wait for my next reflow attempt.


Regards,

paul.

Hey Paul im glad the reflow soldering is going good for you. you should try soldering small smd resistors and capacitors as well, i usually get them in the 0805 package because i find they are not to small to work with and easily handled with normal tweezers.