Get Ahead of Advanced Packaging
These days, you have to scratch your head and wonder what type of component packaging will pop up next. Speaking of pop, that’s exactly where the industry is heading ñ package on package or PoP ñ and it’s well on its way now. In the meantime, not everything has gone PoP. There are still a number of different packages populating today’s PCBs. But they are all advanced. For example, take a look at Fig. 1 showing a very small microCSP compared to the larger SOT 23 package ñ both on a small area of a dime.
When you consider advanced packaging, you also have to think about inspection simply because you need state-of-the-art tools to accurately view and monitor any potential defects in these extremely small packages. Those include micro BGAs and such small passive devices as 0201 and 01005.
In short, aside from advanced PCB assembly systems, the EMS provider or contract manufacturer (CM) must have the best trained, most experienced technicians and engineers on the SMT line to assure no mistakes occur and the job is done correctly the first time when it comes to PCB assembly using advanced packaging. You have to have this high caliber of people and equipment because there is no room for error when dealing with advanced packages.
Check out this link and read our SMT Magazine tech article to get more detail on advanced packaging and the challenges you may have to deal with.
With technology trends so dynamic prevalent when it comes to component packaging, itís a good idea to stay ahead of those trends to avoid any possible issues. Here are some tips to get you started:
- Check with your EMS provider or CM to make sure they have the latest advanced optical inspection or AOI, which can capture the smallest detail.
- If you are using advanced packaging and your CM or EMS provider relies on manual inspection using QC personnel, it might be a good idea to look for another contractor.
- Consider the fact that if a microCSP or microBGA is damaged, chances are about zero that it can be re-worked. This means more cost and production time for a new substitute.
- Look for stringent manufacturing process control to include state-of-the-art AOI, thermal profiling, advanced paste height inspection, printing, and first article inspection (FAI).
- Thermal profiling takes on greater importance since land pattern and surface mount area are highly limited.
- If you are a mil/aero customer, find out if your EMS provider or CM has the capability of creating a three-state thermal profile for vapor phrase technology. This is substituted for conventional convection reflow, particularly for mil/aero PCBs.
Lastly, when it comes to advanced packaging, there are no gull-wings or leads for testing purposes. Such devices as 0201s and 01005s have tiny pads, but all are so small they cannot be used effectively as test points. Such packages as 0603 or 0402 have pads that can be used as test points for flying probe testing.
But for advanced packages, conventional test points are lacking. In these cases, modular, bus, or batch testing must be used. As the name implies, different components are put together and tested in a modular batch fashion at a time, rather than using stand alone test points or the surface mount pads as test points.
This has another effect on a board’s real estate, meaning having more test points than usual to check the functionality 100%. Since surface mount pads cannot be used, separate test points are needed on the top or bottom side of the board for flying probe testing.