-----Original Message-----
From: Russ Winslow
Sent: Friday, March 24, 2006 12:47 PM
To: 'TechNet E-Mail Forum'; 'Dehoyos, Ramon'
Subject: RE: [TN] Tin Whisker Mitigation
Hello Ramon and TechNetters,
Although I'm sure you would rather hear from users rather than suppliers I'll still try to help with your questions.
Our company Six Sigma, specializes in Hot Solder Dip finishes for converting components from lead-free (pure-Sn) back to Sn63Pb37. Six Sigma also converts components from tin-lead to lead-free. This is not a plating process but rather a hot solder dip process.
A company called AEM in San Diego does a replating of chip caps and resistors. In this process they over plate with Sn-Pb then reflow (if required) to combine the two finishes. Since this is a barrel plating operation they cannot handle components with leads.
Six Sigma also does BGA reballing on a large scale.
1. Experiences in doing this effort: Well, first off I would have to say my opinions are mixed. In the past we have worked with lots of board pulls and this has been frustrating. So many times the customers will destroy the component then ask to have it fixed. If they would only do adequate pre-bake before board removal and preheat during removal, reballing would be a whole lot easier.
New components are such a pleasure to work with. Although some of the new ball patterns will blow your mind and a couple of companies are eliminating the nickel barrier plate on the under-ball-metallization. This makes the component self-destruct after a few reflows. The copper dissolves into the ball and a few seconds later, presto no pad.
2. Extra time needed: This depends. (Classic Technet response) If tooling, special alloys, etc are required then lead time can get crazy. In general, small lots of ~300 pieces can be turned within a week. Keep in mind that sending properly packaged dry parts saves a lot of oven time.
3. Cost: Too many unknowns to give pricing at this time. Prices can vary considerably based upon complexity, run time, special requirements and post solder testing. One major factor in the price is the incoming alloy. For example, if the component is tin-lead and the customer wants lead-free then we must dump our solder bath before it reaches 0.1% Pb.
4. Reliability: Not a lot of reliability data has been published however I can say that hot solder dip has been around since the invention of the transistor. It has been regularly used on plastic and ceramic components for decades. Advances in robotic solder dip techniques, non-halogenated fluxes, and controlled thermal profiles have made it a widely accepted process. We strongly recommend qualifying the process by performing acoustic imaging before and after solder dip or reballing. Of course, hermetic components are simply leak tested and inspected for cracks so acoustic imaging is not necessary on these.
The Government Electronics and Information Technology Association (GEIA) is working on an industry standard for "Requirements for Using Solder Dip to Replace the Finish on Electronic Components". If anyone is interested in participating in or keeping informed of our progress please let me know.
I'd be happy to share more details on the processes themselves if you are interested.
Thanks & Regards,
Russ Winslow
Six Sigma
905 Montague Expwy
Milpitas, CA 95035
[log in to unmask]
www.sixsigmaservices.com
Phone (408) 956-0100 x 111
Fax (408) 956-0199
-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Friday, March 24, 2006 7:18 AM
To: [log in to unmask]
Subject: [TN] Tin Whisker Mitigation
Hello TechNetters:
Does anyone know of companies that are replating parts with Sn63
and reballing BGAs? Could any one share their experiences in
doing this effort? Things such as: extra time needed, cost,
reliability.......
Regards and TIA,
Ramon Dehoyos,
410.552.2210
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