Hi,
We have both Vapor Phase ASSCON semi auto as well as Soltec convection inline ovens. I must say we had no end of problems with Vapor Phase. We tried everything, and just could not totally eliminate tomb-stoning completely.
We would always get a more than 10 percent defect rate from the vapor phase, while we often get sub 1 percent from the convection reflow.
We have a lot of expensive boards that still need x-raying to see what's wrong, but they have large BGA parts and we think they either did not reflow correctly, or we got some other kind of component cracking due to overly fast heat up. We don't even use vapor phase for prototyping any longer.
When you study the vapor phase process, it's quite an amazing technology, or you think so at first. The sale guys love to share all the details about it, and they did mention tomb-stoning, as an easy to overcome problem, however we went through many stencil designs, and nothing worked. Funny how the sales guys then referred to it as a process problem that can be fixed, but had no further advice on how. We tried everything.
The solder quality of vapor phase is incredible, and the joints are amazing, but when using in in production in the real world it's these problems that killed the process for us.
Convection reflow with the Soltec is just so stable and reliable, that we use it for everything now. We even run first prototype boards through, unprofiled without problems. We just use a profile with similar component types.
So with experience with both, I would go convection any time. It's also much cheaper to do inline convection, while vapor phase is mostly a batch process, and inline vapor phase is very expensive.
Where I would consider vapor phase is if I had no money and needed to do only prototype boards only. I would then use the pasta cooker on the hot-plate approach using the vapor phase fluid. (The fluid is also expensive) But even in this case I would still get a batch convection oven, and try and mod it to get better airflow than go back to vapor now.
A little about our process. We are doing a few thousand boards a month, and for us vapor phase based faults were too much of a problem. Convection allowed us to go inline, and faults dropped off to almost nothing immediately.
I hope my experience helps. I remember asking the same question on this forum a while ago, and not many people knew much about vapor phase, apart from 1970's based equpment. At least I can share some experience now!
Regards,
Grant
reply »