This summer looks to be a busy time for the Foresite staff.

Terry will be out on our west coast working with clients to resolve process issues. Paco is headed back to Asia, providing client training and on-site process consultations. And Eric will be assisting some of our North American clients in both Canada and Mexico.

Foresite offers educational seminars to manufacturing, quality, and management personnel regarding various topics related to residue identification, product reliability impact, specification compliance, handling precautions, sources of contamination, measurement techniques, and general process control and optimization. If you would like more information regarding on-site opportunities email Eric at ericc@residues.com.

Connector Pin Residues

Over the past two years, we have seen a significant increase in residue investigations involving connector pins. The problem is not isolated to one industry segment. From high reliability avionics to high speed telecommunications, process residues not properly removed from the connectors are proving detrimental to product reliability and performance.

As in other assembly locations, flux residues on pins or in the pin area are wreaking havoc - creating corrosion cells or insulative barriers inside the connectors. The typical ion signature for residual flux is high levels of chloride and weak organic acids.

Another connector culprit is saponifiers, which can be difficult to properly rinse. Typical, water cleaning systems are not capable of reliably and completely removing the residues, so a saponifier wash needs to be utilized to remove the flux residues. The connectors are shielded from the cleaning process due to their orientation on the board which leads to residues being trapped and retained.

Solution - ensure thorough and proper rinsing, directing the spray and/or steam into the connector.

COTS (Commercial Off The Shelf) hardware has been facilitating the integration of new technology into electronics for the last 25 years. However, reliability challenges associated with the use of COTS hardware have steadily grown with the advent of new technology and processing techniques. Below is a brief overview of the many reliability concerns of COTS hardware being used in the Medical, Automotive, Telecom Servers, Industrial Controllers and Portable Cell/PC markets.

As a general rule COTS hardware works across varied market segments when used in applications and environments for which they were designed, but as technology becomes more mobile and globally applied we are seeing an impact on reliability by COTS in the field.

Reliability Concerns Associated with the Use of COTS:

1. Failure mechanisms - electro-migration, electrical leakage due to dirty boards and components, entrapment and incomplete heat activation of fluxes, and entrapment of fabrication and assembly residues due to under-cured soldermask;

2. Surface anomalies - creep corrosion on immersion silver, tin whiskers, marginal solderability of replacement finishes;

3. New component technology (QFNs, micro-BGAs) trapping fluxes;

4. Compatibility issues arising from such instances as mixing leaded and lead-free alloys in high-reliability, RoHS-exempt electronics;

5. Issues associated with increased circuit sensitivity;

6. Discharged batteries.

While the above concerns are not unique to the use of COTS hardware, they can be exacerbated by COTS and additional consideration should be given during their application.