Need help with Printed Circuit Assembly?
First, a question: Is "printed circuit assembly" a noun or a verb? Anyone... Anyone...
We tend to use the phrase "PCB assembly" more often than just "PCA" or "printed circuit assembly". Though, I have been told that "PCA" is a more appropriate noun used to describe our finished product. Regardless of what you call it, pcb assembly, or the printed circuit assembly process or prototype assembly; it's getting a lot more difficult.
I've been paging through a catalog from Practical Components - a manufacturer of dummy components, test boards and training aids. Page 17 shows a dual row MicroLeadFrame package (MLF and MicroLeadFrame are registered trademarks of Amkor Technology). It's basically a QFN with two rows of signal connections and the big heat slug pad in the middle. The signal pads are on a .5mm pitch and this particular line ranges in size from a 9mm square with 108 leads up to a 12mm square with 164 leads. Page 11 shows a CVBGA package that can have 432 balls on a .4mm pitch squeezed into a 13mm square. They have dummy components for just about an size package you might run into.
When I was designing boards, most parts were available in SMT and thru-hole, but you could build just about anything with a smattering of different thru-hole DIP sizes. Not any more. ZigBee radios pretty much only come in QFN packages. Some of the newest embedded processors only come in .4mm BGA packages. I could go on.
You just can't hand assembly these bad boys anymore. That may seem to make things more difficult, but not really. If you simply can't do it, you have to send it out and you can get back to designing. At least that's the way I like to look at it, biased, though I may be.