Building a Reflow Oven: Part 1 – Getting Started

RE: Building a Reflow Oven: Part 1 – Getting Started

michaelkellett — Mon, 28 Jul 2014 13:16:58 GMT

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-1cd3cd78-25ae-4061-88b5-4a929f66d6d6/2388.contentimage_5F00_176866.jpg:620:465]

I bought a gunge dispenser direct from China via Aliexpress for about £75 - very crude (one switch doesn't work properly, footswitch connector broken, leaks air) and you don't get much in the way of needles etc. I then spent as much again on syringe barrels, 2 sensible sized air to syringe thingies that actually clip on and off properly and three different sizes of needle (in packs of 25).

With hindsight the dispenser itself is a waste of time, all you need is a solenoid valve, a timer settable between 10 and 500m s and a pressure regulator.

You can buy a regulator and solenoid valve of decent quality for about £75 (or less if you look hard) and build the timer form almost any micro development board you might have kicking about. The dispensers all talk about having suck back but you only need that for runny stuff - not needed for solder paste.

When this dispenser fails (I don't think I'll need to wait long) I'll make the next one (I even have suitable air parts from an old test rig.).

You can buy a much more reasonable looking dispenser from a UK source for £225. Analog timed glue dispenser adhesive dispensing - this is where I got my barrels and nozzles from.

RE: Building a Reflow Oven: Part 1 – Getting Started

michaelkellett — Mon, 28 Jul 2014 07:34:55 GMT

Hello Shabaz,

It works much better if you can apply some heat to the bottom of the board. I have just bought a cheap Chinese BGA rework machine and like all its competition it works by heating from the bottom at a controlled rate (using IR in my case) and then, once the board is hot but below solder melting point, applying IR heat from the top (some use blown hot air) to get the chips up to the right temperature. It has a feedback thermocouple.

I haven't used it seriously yet.

So far I've had good success with LQFP by heating them on a hot plate. It's important to start from cold so that the volatile stuff has time to evaporate out of the solder paste before the solder melts otherwise you get a lot of viscous bubbling and heaving and can end up with big voids in the solder.

How will you apply the solder ?

RE: Building a Reflow Oven: Part 1 – Getting Started

Problemchild — Sun, 27 Jul 2014 21:19:57 GMT

Nice project , I like the measurement aspects. I hope you will be able to share the heating measurements when you have finished assembling the test rig !

RE: Building a Reflow Oven: Part 1 – Getting Started

jw0752 — Sun, 27 Jul 2014 19:43:05 GMT

In my professional area, dental equipment service, we often had to deal with a piece of equipment called a dry heat sterilizer. This came in two different styles one using radiant heat, like a toaster oven, and the other using heated forced air, like the heat guns or a hot air popcorn popper, into a partially enclosed chamber. While normal operating temperatures for these pieces of equipment was only about 200 degrees C they had controllers that were fairly accurate and stable. I suspect that they could be modified into the temperature area that you are exploring. If you have a dental equipment service facility in your area you might check to see if they have an old unit where you could salvage a temperature sensor and control. I would assume that your goal is to produce something with uniform and accurate heat distribution. Most of the sterilizers had polished stainless internal chambers to reflect and scatter the radiation around the chamber. Something that might make a pretty good chamber would be a piece of stainless insulated wood stove chimney pipe. It would combine the reflectivity of stainless and include insulation.

John

RE: Building a Reflow Oven: Part 1 – Getting Started

jw0752 — Sun, 27 Jul 2014 19:01:33 GMT

Thanks for sharing your experiment with us.

John

RE: Building a Reflow Oven: Part 1 – Getting Started

fvan — Sun, 27 Jul 2014 17:42:39 GMT

Sounds like the outcome of this project could be very interesting for a lot of hobbyists, I like it [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-1cd3cd78-25ae-4061-88b5-4a929f66d6d6/contentimage_5F00_1.png:16:16]

Frederick