Reflow Takes On Greater Meaning (and requirements)
PCB reflow is continually changing and it is no wonder since board and component technologies are dramatically advancing as you, the OEM, require greater product performance and reliability in smaller form factors to meet your market demands. A decade ago, motherboards measured 10×12-inches, but now they’re in the range of 6×6-inches as a result of shrinking component sizes of microBGAs, QFNs, and CSPs. But at the same time, processing power designed into these smaller PCBs has escalated by 100 times or more.
These PCB advances challenge the reflow of advanced packaging to the point that special attention must be applied to each and every aspect of this process.
Check out the September/October issue of SMT Magazine for our article providing you greater details about reflowing advanced packaging. The article gives you an in-depth understanding of the steps and procedures a CM and EMS provider must apply to minimize assembly problems with your PCB projects.
As a preview, here are some tips you can follow to assure that your PCB project is getting the right level of reflow attention:
- Make sure the PCB designer makes a thermal analysis before your PCBs undergo assembly.
- Obtain assurances the PCB designer understands all the nuances involved with new and advanced packages. For instance, leadless BGAs present certain challenges and issues during printing and reflow.
- Understand the requirements of the correct thermal profile for your PCB project. Remember not all thermal profiles are created equal.
- Watch for red flags when your CM tries to convince you he has an ‘off-the-shelf’ thermal profile for your PCBs populated with advanced packaging.
- Get a good handle on solder paste because it has the potential of affecting different fluxes and the level of performance under certain temperatures.
- Assure yourself that your CM has the most advanced equipment, such as inkjet printing (see MY500 printer photo), to provide you the highest possible reflow capability.
The bottom line is you want a tightly controlled reflow process. This demands the most up to date techniques, personnel training and equipment applied to your PCB project. Verifying reflow temperature is a routine procedure for most experienced CMs. But in the case of advanced packaging, it is ultra critical since minimal history exists about accurately reflowing advanced packaging. These devices are still new on the market and more sophisticated versions are continually being introduced. Certainly, device manufacturers provide datasheet recommendations. However, the savvy CM performs sufficient experimentation and in-house prototypes to validate new advanced packages.