Steps for determining the root cause of peeling problems.

Picking the right tool for electrochemical contamination at the rework bench.

A half-dozen versions of the same scenario occurred in the past month, all having to do with materials and processes used in post-op/rework applications. This step of the production process often escapes the attention of engineers because there’s no cool machinery or any real engineering that takes place. Most hand-solder operators are highly proficient and have developed techniques that get the job done, which can lull a supervisor or production manager into a false sense of security. Electrochemical contamination doesn’t normally appear until it has become a dreaded field failure. In fact, if the issue is contamination/corrosion/leakage-related, the first place I look is the rework bench, and eight times out of 10 that’s where the trouble spots lie.

Manual soldering applications have different requirements than upstream processes, and it’s worth detailing these differences to understand the importance of materials selection and proper usage.

Adding just enough material for a set amount of prints can ensure good outcomes.

Although no-clean solder pastes are the most prevalent materials used in electronics assembly today, water-soluble pastes are still in the game. In market sectors like aerospace, military, automotive and industrial, water-soluble materials are frequently the specified-in, legacy product – often because of the reliability requirements to remove flux residues. Printing water-soluble solder pastes, however, is quite a different process than printing no-clean materials. Assembly specialists take note!

Back in the day, no-clean pastes were the more fickle materials, with delicate operating windows and strict storage requirements. Over the years, massive amounts of development and a focus on maximizing process efficiency (i.e., eliminating an unnecessary cleaning step) put no-clean in the processability fast lane, while water-soluble material R&D got lapped. Although new water-soluble pastes have been released in recent years, they are still generally more difficult to print than no-clean pastes, and the finesse required to successfully print them isn’t always well understood. Put simply, the primary challenge with water-soluble pastes is they are hydroscopic (absorb water) in their function, making them a bit sponge-like.

And more important, who will it affect, and how?

It’s difficult to turn on a TV or read a major newspaper without seeing mention of Foxconn and the $10 billion flat-panel manufacturing facility targeted for southeastern Wisconsin. On one hand, it’s great to hear manufacturing jobs may be created on the scale being bandied about: 3,000 near-term, according to Foxconn’s quotes in several publications, and 13,000 (with an average pay of $53,000 plus benefits), according to Wisconsin Gov. Scott Walker. And while I don’t relish the idea of Foxconn becoming the poster child for the electronics manufacturing services (EMS) industry, after decades of working in and consulting to participants that are rarely known outside of electronics, it is nice to see the industry get this type of national recognition.

But will it happen? Foxconn’s track record isn’t stellar. A highly touted deal in Pennsylvania that involved a $30 million investment and 500 workers didn’t happen. Previously announced investments in Indonesia, India, Vietnam and Brazil have either yet to occur or were far below original projections.