Advice in buying my first SMD reflow Oven

[ikalogic]

Hello,

I am going to buy this:
**broken link removed**
Or anything better if you can convince me!

My question is, in general, how to we do when there are components on the two faces? how to prevent components on the bottom face from falling down when melting the top face?

Are there some proven techniques?

Thanks!

 

[ikalogic]

I think i got my answer by watching this video:
Double sided surface mount PCB population - Hack a Day

Is there any better/simpler way than applying epoxy?

 

[3v0]

I think this controller is interesting

 

[ikalogic]

Thanks 3v0

So, epoxy is the only known solution?

Ain't there anything less messy?

 

[3v0]

Given that no one seems to have an answer. I saw a video on doing 2 sided SMD. They did not glue the parts to the bottom. I think they did the bottom first and then added top parts. During the 2nd reflow the surface tension of the bottom solder held the parts in place. Not 100% sure.. foggy recall

 

[RCinFLA]

I used to work for large firm doing double side boards.

Two separate reflows are done. First side reflowed, then second side screen printed and reflowed again.
Dedicated fixture plate was made to allow second screen printing with parts soldered on other side.

The reflowed solder will hold normal parts on board upside down during second reflow.

Choice of which side goes first depends on parts. Large parts or parts stressed by reflow go on second pass to avoid subjecting them to two reflows.

Because we were doing fine pitch BGA parts, the boards are bare copper to get maximum flatness. There is a light coating over copper that retards copper oxidation. This protection evaporates on first reflow (on both sides) so second side processing must occur within a hour.

Boards from vendor come vaccum packaged, not to be opened until assembly process begins.

 

[Boncuk]

Hi Ibrahim,

I do not recommend to purchase the Elektor reflow oven.

There was a thorough experience report in the (German Elektor) forum telling about blisters in soldered connections and missed soldered pins for the fan driver transistor on the controller board and almost shorts between the MCU pins.

The Elektor oven is manufactured in China based on Elektor's plans and is quite expensive (€1500) + €50 for shipping.

The preheat phase is much too short and the baking temperature exceeds 290deg/C. Temperature distribution is a desaster with the temperature probe "miles away" from the object.

First test result was a crispy PCB which had to go directly to the waste.

Here is a more promising reflow oven manufactured by Madell (I guess it's a French company).

Check out Madell Technology Corporation for info about their reflow oven and other useful SMT-machines.

The only way to achieve equal temperatures all over the oven is a double wall device with holes in the inner wall distributed all over the chamber and a hot air fan with ambient air cooling for the fan motor which I saw at work at Motorola. This reflow oven kept the objects in an atmosphere of Argon to prevent oxidation during the reflow process.

With a hot air fan the cooling phase can be controlled precisely by opening a Y-air-valve to have ambient air expedite or slow down cooling - no matter how long the heating element stays hot.

The Elektor oven omits the controlled cooling phase which might lead to material tensions and early breakage of the board.

I also saw a "cheap" reflow station at work using a "tunnel" for soldering. Small parts like 0805 type resistors erected themselves like "grave stones" and had to be resoldered manually.

Regards

Hans

 

[ronsimpson]

I use a "toaster oven". $5.00 us (used) $50.00 new.
I do not follow the "temperature curve" but watch for the solder to melt. The large parts flow last so that is what I watch. The paste is gray and liquid solder is silver. So it is easy to see.

 

[Ian Rogers]

Sorry Ron... Thread re-opened by spammer!!!