I apologize in advance for having to be harsh in my commentary.

As someone with over 30 years in electronics manufacturing the first thought I had when reading this article was: This is an incredibly stupid idea.

Do not try to play manufacturing engineer with your kitchen oven. You will, without a doubt, cause more harm than good. Not to mention coating the oven where you cook your food with stuff you don't want in your food.

Modern high density RoHS electronics boards require higher temperatures in precisely timed and controlled vapor phase reflow ovens. Components, solder joints and the board itself will almost certainly suffer damage from uncontrolled non-vapor profiles in a kitchen oven.

It is far more likely that components will be exposed to far greater temperatures than rated as well as all kinds of imaginable differential heating and thermal slew rates. You can destroy the vias and pads connecting multiple layers of a multi-layer PCB simply by having differential heating or high temperatures. You can also damage dielectrics in precise impedance controlled boards. You can cause problems with solder that might very much affect signal integrity in high speed signals (for example, around the memory subsystem).

In general terms, you are very much opening Pandora's Box if you think you can use a kitchen oven to reflow a modern mid to high complexity circuit board.

Beyond that, you don't have the necessary optical, x-ray and high-speed testing equipment required to verify operation. You don't even have access to design data needed to understand where critical paths might lie.

Sorry. This is a really dumb idea.

Then we move on to drilling holes for the fans. OK, great, yes, more cool air molecules per unit time is what cooling is about. However, this design does not have any air filtration mechanisms. So, by drilling a bunch of holes you are far more likely to create a situation where you will coat the entire inside of the computer with a layer of dust and dirt with the potential to cause major issues.

If I had no choice but to cut holes on the bottom on one of these machines I'd take the time to engineer a bolt-on filter plate with washable filters so that the internals might be protected from contamination (within reason).

A far better idea might be (more on that later) to engineer the attachment of a surface extension feature on the bottom of the machine rather than drilling ventilation holes. "Surface extension" is what you commonly see on heatsinks, in other words, fins. Anyone who's done thermal FEA quickly understands that designing thermal management by eye only works if you have a lot of experience. These machines probably have decent thermal design. Perhaps all that is needed to make them a bit better is to add 10 mm of metal to the bottom with a nice thick set of fins widely spaced in order to extend the surface and promote thermal exchange with ambient air.

Final point on TIM's (Thermal Interface Materials) like thermal paste. Their main purpose in life is to take two non-perfect surfaces and bridge the little imperfections so that more molecules make a thermal connection between surface A and surface B. If you could polish both surfaces to absolute perfection and mate them to absolute perfection you would not need TIM's. When it comes to thermal paste, you want as little as possible and you do not want any air gaps. To some degree there's an art to applying these kinds of TIMs.

The author talked about buying some copper sheet in an attempt to fix the problem. Again, horrible idea. You have have two layers of TIM, on one each side of the copper sheet.

In the hands of those without the requisite knowledge or experience I feel that ceramic sheet-based TIMs are far safer (http://goo.gl/Q6e0Es).

But I digress. The best idea would have been to walk the machine to Apple and deal with it through their channel. That's what they do best.

The good news is that this kitchen-reflow machine is unlikely to make it to the used market due to the drilling on the bottom. I would hope that the author will be honest enough to disclose the amateur reflowing of the main board if and when the machine is ever sold in the used market.