Originally from Krista Botsford of 5-Trees:

China RoHS is confusing. With:

• no official translation available, and


• no official direction form the Chinese Government,

Definition of

EIP

: from AeA Translation of “China RoHS”

Electronic information products refer to the products and accessories
manufactured with electronic information technology including
electronic radar products, electronic communication products,
broadcasting and television products, computer products, household
electronic appliances, electronic surveying instruments, specialized
electronic products, electronic components, electronic application
products, and electronic material products.

Folks,

We are all aware that the miniaturization of electronics continues unabated. As consumers we benefit from this phenomenon, as electronic assemblers we struggle with it. The smaller stencil aperture openings make stencil printing more of a challenge, while at the same time reflow is more difficult because the small solder paste deposits have a higher surface area to volume ratio (SAVR)*. This greater SAVR makes more work for the solder paste flux to remove and prevent oxidation.

As many in the industry go halogen-free, the larger SAVR will be an even greater challenge. So look for continued improvements in halogen-free solder pastes Re their fluxing ability.

Another interesting effect of smaller solder joints is that it is possible, especially if cooling is slow coming out of the reflow oven, for the small solder joint for be a single solder grain. If the orientation of this single grain is such that its weakest direction is the same as that of the maximum stress on the solder joint, mechanical failure can occur.

A short time ago I had a posting on the trend that SAC305 appears to be fading in favor of SAC105. I mentioned that before SAC105 can be dominate, sister alloys (similar to SAC105 but with additional additives) will need to be developed that lower SAC105’s melting temperature from 227C closer to SAC305’s 217 and improve SAC105s fatigue life and further improve its shock resistance. In addition to these needs, this new, as yet to be defined alloy, (often called SACY) will benefit if it resists forming single grains upon cooling.

It is an interesting and challenging time to be a solder metallurgist!

Cheers,

Dr. Ron

*
To understand why SAVR becomes so great as solder deposits become smaller, consider a sphere. Its surface area is given by 4 Pi r^2, whereas its volume is 4/3 Pi r^3. The SAVR is then 4 Pi r^2/(4/3 Pi r^3) = 3/r. Hence, SAVR becomes infinite as r=>0!

The photo of passives is from a paper I co-authored with Rita Mohanty of Speedline, etal. (Mohanty, Rita, Lasky, Ronald, etal, Process Development for 01005 Lead-Free Passive Assembly: Stencil Printing, APEX, Los Angeles, February 2007).

Folks,

Circuitnet recently had a posting stating that RoHS has cost industry, and hence we the consumer $32 billion. I’d say that’s about right. The article goes on to state that this is essentially 1.1% of the value of electronics production, this seems a bit low to me since about $1 trillion of electronics are manufactured world-wide each year.

Anyway, I imagine many are surprised and outraged at this “unwarranted tax”, arguing that no study has shown that RoHS protects the environment. Regular readers will remember that I continually point out that RoHS exists primarily to make recycling safer. As electronics products continue to grow in quantity, recycling will become pervasive. We all hope the recycling will be performed safely and should take some comfort that RoHS makes it easier and safer for a professional recycler to recycle.

However, as I have pointed out in a recent posting much recycling is and will continue to be done in third countries. So to me, paying $10 to $20 more for a $1000 PC to make it safer for the young boy in the above photo, from the January 2008 National Goegraphic, is a small price to pay.

Cheers,

Dr. Ron

Folks,

I was asked to guest blog for All-Spec. The topic I choose was the status of RoHS and RoHS 2 concerns. Check out the post.

The photo above is of the EU Parliament, in Brussels, where the RoHS laws are made. I found the photo by using Google Images.

Cheers,

Dr. Ron

Folks,

1. APEX appeared to be a big success. The Las Vegas venue also seemed to be a big hit. Since I’m not a big fan of gambling or smoking (the casinos are not smoke free!) these aspects were a tad disappointing, however it was much more convenient than last year in LA.

Halogen-free interest did not disappoint. My colleague Tim Jensen attended a standards meeting on the topic and about 80 souls were there. Although session attendance was good (the one I chaired and the one I presented at each had about 50 attendees) 80 might have been as large as any tech session.

I was interviewed by the iconnect007 folks Re RoHS, RoHS 2, halogen free and lead-free reliability. Check the video out.

2. The list of the 46 proposed RoHS 2 substances is available. The good news is the EU is asking for input, as in the past. I am probably alone in thinking that the EU will handle the topic cautiously.

3. Tim Jensen and my workshop on Halogen Free has been tentatively accepted by SMTAI

4. And finally, Tiger did not win the Masters (2nd place) or the tournament before that (5th place) consistent with my posting a 3 weeks ago. Statistical variation makes it hard to never lose, even when you are the best!

The photo above is of the Las Vegas “Strip” at night, I found it on Google Images.

Cheers,

Dr. Ron

Folks,

About two years ago it appeared that SAC305 (3.0% silver, 0.5% Cu, the balance tin) was becoming the de-facto standard for Pb-Free assembly. With the increased need for shock resistance in consumer products such as mobile phones and iPod type devices, SAC305 is starting to lose favor. The reason being, that in drop tests (i.e a device is dropped on a cement floor from a certain height, x times) SAC305 performs worse than tin-lead solder and worse than SAC105. So some mobile device manufacturers are switching to SAC105. The current very high cost of silver has helped “grease the skids” for this transistion.

This topic has raised interest among solder scientists. It is accepted that the silver in SAC305 causes silver tin intermetallic platelets (see photo). These platelets cause mechanical stress raisers that lower shock resistance. Since SAC105 has less silver, it forms few platelets and as a result performs better in drop tests.

Unfortunately, SAC105 melts at about 227C about 10C higher than SAC305’s 217C or so. SAC105 also performs poorly in thermal cycle testing. So folks are investigating adding small amounts of other alloying elements to further improve shock resistance, obtain better thermal cycle fatigue life, and also lower the melting temperature closer to 217C.

Along with halogen free assembly, I expect this to be one of the defining issues in assembly materials for the near future.

Cheers,

Dr. Ron

BTW, I am writing this at APEX 2008. The show seems well attended and as expected, halogen-free assembly is a big issue.

David writes,

Dear Dr. Ron,
I thought you would find the article below of interest. Is appears that now there is more than just Occam to worry about. It looks like Georgia Tech is now promoting solder free assembly also. Do you think that solder on its way out?
Thanks,
David

The Georgia Tech article that David refers to is interesting.
Given my lack of enthusiasm for the Occam process, several of you have asked my thoughts about this recent work at Georgia Tech (GT). The Georgia Tech work, sponsored by the prestigious Semiconductor Research Corp, has as its motivation the truth that solder may not have adequate electrical properties (copper has about 7 times the electrical conductivity of solder) to enable some high speed signal operations between ICs. In these situations, a copper connection may be needed for the effective functioning of the ICs. This need will only become greater as ICs increase their clock frequencies and data rates.

This assembly operation starts with a standard PWB and components both having copper pillars. See Tyler Osborn’s photo above. It then uses an electroless plating process to bond the component pillars to the PWB pillars. This process likely does not need much additive plating time as only a connection is being plated between the two pillars (maybe less than 1 micrometer of plating). The GT folks also built prototypes before announcing their process, and they estimate a couple of years for scale up. To me all of this sounds like a winning combination.

It may be a little optimistic to assume that this process will completely replace soldered assembly. It still requires mixing assembly and fab processes together and the final product is not easy to repair or disassemble for recycling. However, they may have conquered, in my opinion the biggest issue facing the Occam process: additive plating time. Since they start with a solder pillars and a standard PWB, they likely won’t require the hours of additive plating time Occam needs to plate > 1mil of copper to replace the PWB traces.

This effort at GT has high credibility in that Intel, TI and Applied Materials are all evaluating the technology.

Is solder on the way out? I would be surprised, as for the vast majority of electrical connections it has adequate electrical properties, is reworkable and promotes easy disassembly for recycling in a world more and more committed to sustainable electronics. So I see the GT process as a candidate to address the high signal speed/data rate issues for a few high performance ICs. I also agree that the need for a pure copper process like this will likely increase over time. I will be surprised if it replaces soldered assembly completely. However, we in the electronics materials industry think the best solution should be the winner. So if there comes a time when solder has served its purpose we must all move on and we will……..I however, will be surprised if this change occurs within this generation.

Cheers,

Dr. Ron

Folks,

In my blog posting of December 1, 2005, I asked PC Magazine’s “Cranky Geek” John Dvorak about his knowledge of RoHS. He admitted to being unaware at that time. Well PC Magazine has now gone “green” and is knowledgeable not only on RoHS, but also other green metrics, such as recycling, and carbon footprints. Their April 2008 issue is labeled The Green Issue. The most shocking statistic from the issue: All of the obsolete computers in the US would make a 22 story mountain that would cover the entire 472 square miles of greater Los Angeles. Yikes! WEEE, RoHS and Green are here to stay.

Interest in halogen free solders and assembly continues to grow, even in spite of the controversy of whether or not it is a valid green issue for solder. Many of us think that halogen free will be the topic of this year in electronic assembly materials. Due to this interest Tim Jensen of Indium is starting a Halogen Free Blog.

The image above is from the January 2008 edition of National Geographic….as I said, the need for recycling is now mainstream.

Cheers,

Dr. Ron

Folks,

I wanted to post this before today’s CA World Golf Championship and I promise to get back to more technical topics. But part of this post relates to statistical thinking and data-driven decision making.

I don’t think Tiger Wood’s has many bigger fans than me. I want him to win golf’s grand slam (The Masters, US Open, British Open, and PGA)....it has never been done in one year. Jim McCabe of the Boston Globe even suggested that Tiger might win every tournament he plays this year.
I would be thrilled to see this happen, it is great to see the best ever in golf and perhaps all sports make his unique mark.

However, I’m a doubter. Why? Statistics. As good as he is, he has statistical variation in his play, as do his opponents. In the statistics class I teach at Dartmouth I have the students do a Monte Carlo simulation of Tiger and the next 5 or 10 best golfers. In the past Tiger was, on average, about 1 stroke better per round than the others. In this type of simulation he wins about 40% (with 5 next best golfers, probably more reasonable than 10) of the time…..about his long term percentage

Today his 66.3 strokes per round is almost two strokes better than the next lowest, Luke Donald’s 68.22. So such a simulation would favor him more, however I will be surprised if he maintains the 66.3.

We also need to remember that he was almost eliminated twice in the recent match play championship and that he sunk an amazing 25 foot putt on the last hole to win last week. If these situations happen a few more times, statistics will eventually favor one of his opponents.

I hope I’m wrong!

Cheers,

Dr. Ron

Folks,

In 2002 Phil Zarrow, Jim Hall and I worked with the folks at SMTA to develop a Certification Program for SMT Process Engineers. Hundreds have been certified since then. The program is now taking off in China.

As Phil likes to say: “We are all in this together.”

Congratulations SMTA!

Cheers,

Dr. Ron