Issue



Commonly Asked Lead-free Cleaning Questions


03/01/2006







By Tom Forsythe, Kyzen Corp.

When considering cleaning lead-free residues, what needs to be asked first: must I, should I, can I, can I afford to, or can I afford not to? These are the questions that come to mind, with new, lead-free advanced packages and devices coming into production.

Must I? The answer starts with customers. They are the decision-makers regarding the appropriate standard of product quality and reliability required for their product. If the customer says “yes,” then we must clean. However, the issue is often not that clear. The customer may not have an opinion regarding cleaning, but they certainly will have an opinion regarding quality. The challenge to meet reliability and quality standards is then left to the device or package manufacturer.

Should I? It is common to encounter a production process with serious yield challenges. The modest cost of cleaning routinely solves that challenge, allowing the program to proceed and meet the required economic goals. So, often the answer is “Yes, I should clean.”

Can I? After all, isn’t it called “no-clean?” What if that implies “can’t clean?” What about these high-temperature, lead-free residues? These are all good questions. There was a time when first-generation, no-clean materials should have been called “can’t cleans,” although that stage of development was brief. There is no doubt that modern lead-free materials can be challenging to clean, particularly if you are concerned about the process cost-of-ownership.

Can I afford to? It is easy to forget that yield losses are expensive. If a cleaning process improves those yields, the cost tends to be modest. However, there are some critical points that are worth serious consideration. There are thousands of cleaning processes operating today that work well on the task they were designed to address. New, lead-free materials represent more of a revolutionary change to soldering technology than the more typical evolutionary approach. In some cases, new technology is kind to legacy cleaning materials that have worked so effectively for years. In many cases, there are challenges. In no way do these castigate tried-and-true materials, but if a 10-year-old product works on a new lead-free solder, it’s probably due to luck rather than good design. Luck can be a reasonable plan, but only for so long.

The key to an affordable lead-free cleaning process is modern and designed for lead-free cleaning materials. This concept is not limited to cleaning. Would you use a 10-year-old analog design for your latest Bluetooth digital product? One suspects not.

Modern materials were developed to target new lead-free materials. Their developmental testing included lead-free materials from suppliers worldwide. No wonder they are effective and deliver reduced cost-of-ownership when compared to older legacy materials. The answer to the question, “Can I afford to?” is yes, even more emphatically with modern materials.

Can I afford not to? This question has a more strategic aspect to it because of the competition for contracts. If the competition has a modern, robust cleaning process that provides them with “improved” process yields and an overall lower-cost operation, who has the advantage, particularly if it involves lead-free materials?

Consider, also, ongoing business. All companies have relatively mature products in production that run at high levels on multi-year arrangements. This production can be re-bid from time to time. The competition, with a modern cleaning process and current equipment designed for lead-free solders, will also provide lower cost-of-ownership than the older legacy technology, whether you are running lead-free or eutectic. This would be a good time to ask, “Can I afford not to?”

The question that should be asked is why so many advanced packaging houses avoid evaluating whether cleaning would improve their bottom line? Our industry is all about science and data. So often, those controlling the process rule out the consideration of cleaning; routinely without data and often to their own detriment. As leading suppliers can do all or most of the testing at no cost to the customer, there seems to be little to lose and much to gain just by asking a few questions.

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TOM FORSYTHE, VP, may be contacted at Kyzen Corp., 430 Harding Industrial Dr., Nashville, TN 37211; 615/831-0888; E-mail: tom_forsythe@kyzen.com.