Tighter Scrutiny Needed for PCB Cleaning Agents


Reading time ( words)

PCB cleanliness on the assembly floor is now getting more attention, due to tiny residues and contaminants being left on assemblies after new, advanced assembly processes. Cleaning methodologies, testing, analysis, and special chemistries are being taken to a new level to assure customers of ultraclean boards to avoid costly latent issues.

Board cleanliness is especially critical for mil/aero and medical applications. The right types (and amounts) of cleaning agents must remove flux residues to assure the integrity of processes such as bonding and conformal coating. During the coating process, if residues result in poor wetting or delamination, they can cause assembly failures and ultimately lead to field failures.

In today’s assemblies, there are growing numbers of advanced packages like land grid arrays (LGAs), fine pitch BGAs, micro BGAs, micro CSPs, and the list goes on. Packages such as LGAs are flush to the board, and they have bumps, not balls or spheres, like BGAs.

If a small amount of flux remains trapped under the board’s surface, it can change the characteristics of impedance, resistivity. This could also change what could have been a perfect eye diagram, and in general, change the optimal level of operation. Ultra cleanliness is even more critical if underfill or conformal coating is applied to a device.

It’s difficult to clean such a device after the board has been processed. Therefore, assembly personnel have to be absolutely sure they’ve taken every possible measure to assure devices and boards are ultraclean. If residues are left in the conformal coating or underfill, then these contaminants are trapped inside the capsule and hinder device performance.

Read the full column here.


Editor's Note: This column originally appeared in the April 2014 issue of SMT Magazine.

Share

Print


Suggested Items

Tips & Tricks: Water Contamination and Flux Expiry

04/17/2019 | Jason Fullerton, MacDermid Alpha Electronics Solutions
Solder joints that form properly are not expected to exhibit reduced reliability. However, a higher number of defects created tends to lead to a higher chance that defective connections escape detection through inspection and functional testing, and that’s not a risk to be taken lightly.

Which IPC-A-610 Class is Best for Your PCBA?

04/08/2019 | Neil Sharp, JJS Manufacturing
For many EMS providers, IPC-A-610 is the agreed standard to define what's acceptable and what's not in the world of PCBA production. As an OEM, it's important that you're clear on the basic principles that separate those classes so that you have a clear and realistic expectation of what the results are going to be.

Bill Cardoso Discusses Creative Electron’s Inspection Strategy

04/03/2019 | Tim Haag and Barry Matties, I-Connect007
At PCB West in Santa Clara, California, Dr. Bill Cardoso of Creative Electron held a class on advanced packaging and X-ray inspection strategy. Guest Editor Tim Haag and Publisher Barry Matties met with Bill to further discuss his class and the importance of turning inspection data into information.



Copyright © 2019 I-Connect007. All rights reserved.