INDIUM CORPORATION

最近的客戶拜訪中，大家都對Indium公司的新焊錫棒(Solder Bar) Sn995十分感興趣。 Sn995是一種無鉛的焊錫材料，不含銀，主要成分是99.5%的Sn, 大約0.5%的Cu, 還有一些微量元素。Sn995的主要微量元素，是Cobalt 鈷 (Co)。

先在市面上的無鉛焊錫棒，除了SAC305， 也有很多SnCu+Ni的材料。在我們各種可靠性試驗中，都發現“Cobalt is a better grain refiner.”

²       Functional Test 整板功能性測試

²       Thermal Cycling Test 熱循環測試

²       Intermetallic Growth Test

²       Wetting Test 潤濕測試

²       Shear Test 剪切力測試 

²       Pull Test 拉力測試

²       Accelerated Aging Test 老化測試

²       Hole Fill test 填孔測試

²       Copper Loading Test

²       Dross Test

在以上的所有測試試驗中，Sn995 都呈現出相同或是更好的性能。進一步的詳細測試信息，歡迎隨時聯係我們: askus@indium.com china@indium.com

Cheers!

Picture: Jim Hevel with Indium Corporation

Folks,

I was in the Dartmouth College computer store in 2004 or 2005 and I saw a signed that proclaimed: “After July 1^st computer services will no longer support Apple Macintosh.”

By 2008, however, I noticed more and more of my students using Macs. This trend was important to me as I use Minitab® software in two of my classes. Newer versions of Minitab only support Windows.

This year, so many of my students use Macs, that I have to hold the classes in which I teach Minitab in the engineering department’s computer lab, as I want the students to follow me on a computer.

I was recently told that 75% of the incoming freshman at Dartmouth will be using Macs. All of this in spite of Macs significantly greater cost over a Windows based PC.

Since the students at our colleges and universities will be tomorrow’s leaders, this may portend big changes ahead in computing.

Folks,

The adventures of Patty and Rob continue.......

Rob bolted upright in bed. He had that terrible feeling that he had overslept for an important appointment. His eyes quickly found the clock and it said 10:30! 

“Wait a minute!” he thought, “It’s Sunday.”

He looked a Patty peacefully sleeping and decided to let her sleep. They had had a tough two months. Ever since they proposed increasing uptime to greater than 60% on two “experimental lines”, they were working 90 hour weeks. They just felt they needed to constantly monitor two lines, to assure that things were going smoothly. They felt satisfaction that they achieved 68.8% uptime in a two month period, compared to the company average 30.4%, which is still very good.

The local newspaper got word of this effort and did a story on Rob and Patty’s work. The article was well written and very complimentary to both he and Patty, as well as ACME. Sam Watkins, the site general manager, was very pleased with the good PR. The accompanying photos were really nice too.

The big shocker came this past Tuesday. “Sixty Minutes” called and said they wanted to do a segment on “The US Competing with the Far East in Electronics Manufacturing.” In agreeing to be interviewed, Rob and Patty insisted that members of their ACME team be included. In addition, they felt it was only fair to include the efforts of Rita from their stencil printer and reflow oven supplier and States, their colleague from the component placement company. And they couldn’t forget Eric, from ACME’s prime solder paste supplier. These three folks helped Rob and Patty and their team to develop the plan to achieve the 60+% uptime.

An even bigger shocker came when the Sixty Minutes crew told them that Andy Grove would be in the segment because of his recent article in Business Week, How America Can Create Jobs

 Grove insisted that to participate in the piece, he wanted to visit ACME to see what Rob and Patty were doing. So the Sixty Minutes crew was visiting ACME’s plant this week as were Rita, States, Eric and now “Andy.”

“Maybe we should call him Mr. Grove,” Rob thought.

Rob had suggested that he and Patty go to Berdick’s in nearby Walpole, NH for Sunday brunch and then to play golf. Rob had to chuckle, it was mid July and he and Patty had played golf 27 times (she kept a spreadsheet), he had beaten her 14 times and she was miffed. Even during their 90 hour weeks they would take a break 3 times a week to play 9 holes.

On Monday they were meeting with site GM, Sam Watkins, to discuss what they would tell Sixty Minutes.

Rob and Patty’s Sunday was delightful. The brunch was delicious and relaxing and they both played golf well, Patty’s 68 beating Rob’s 69.

It seemed like no time at all and Rob and Patty were in Sam’s office.

“Just assure me that this Sixty Minutes thing is not some expose that will embarrass ACME or put me in jail,” he teased.

Patty took the lead and explained what they had done. They trained the operators on the importance of line uptime, they worked with Rita, States, and Eric to develop a plan to assure that there would be minimum unscheduled downtime. They had to order extra spare parts and solder paste to assure no stoppages due to parts or paste shortages. One obvious thing is that they would be using two times or more the normal amount of solder paste. The two lines in the high uptime experiment had an average of one change over per day, consistent with ACME’s business.

They also increased routine maintenance on all machines. Both this maintenance and added spares was an increased cost, but these costs were second order effects compared to the dramatic profit increases due to almost 70% uptime.

Preparation for the next three jobs for each line was meticulous, so that setup time was minimized.  Feeder racks were used extensively in minimizing setup time for changeovers. In addition tape splicing was employed to minimize any assist time for component placement. States’ help was crucial in the component placement part of their efforts, Rob pointed out.

Patty went on to describe how Rita helped them in their efforts to develop minimum assist times for the stencil printing process.  The reflow oven presented the least concerns in assist or unscheduled downtime.

The solder paste they selected was robust in that it had a very good response to pause, excellent tack, and minimal slump.  The paste also had the best track record for minimizing defects like Head-in-Pillow and Graping.  Eric also participated as an enthusiastic partner in the effort.

Patty mentioned that their colleague, Phil, had agreed to monitor uptime for two standard lines during the two month trial to compare downtime metrics to the high uptime experiment. These would be experimental “controls.”

She then showed the uptime data for the two high uptime lines and Phil’s control lines. The control lines had ACME’s respectable 30% uptime, but the high uptime lines had almost 70% uptime. Rob went on to explain all of the things the team did to minimize downtime, most of it was common sense. Sam was especially interested in one downtime category.

“What is floundering time?" Sam asked.

 “That is time when the line is not operating due to some unplanned error,” Rob answered.

“Can you give an example?” asked Sam.

“Sure, you know how we have a quite organized approach to setups?” Rob responded.

“You mean our use of white boards to write down all of the things needed for the next 3 jobs on each line?” Sam came back.

“Yes, that is one of our biggest sources of floundering time,” Rob replied. He went on, “Someone will write that they have the stencil for the next job, when they just think they know where it is. When it comes time for that job the stencil cannot be found and an hour is lost.”

“Phil also noted a case where a job was finished on a line at 11:15AM, since lunch was at 12 noon, the changeover for the new job was not started until after lunch. Forty five minutes was lost, forever,” Patty added.

Sam gulped.

“So we are losing more than 25% uptime to ‘floundering?’” Sam weakly asked.

“According to the Professor, it’s endemic in the industry,” Patty interjected. “He coined the term, ‘Floundering time’,” she went on.

Sam then mentioned how the “bean counters” at ACME we really impressed with the two high uptime lines. ACME’s CEO wants a concerted effort to transition all of ACME’s assembly lines in North America  to higher uptime performance. Manufacturing in North America would also mean no 2-4 weeks of transportation time from the Far East. Patty, Rob, and their “team” were to form a new group in ACME to do this. Patty would be the Director of the group.

As the meeting was about to close, Sam asked what surprises Patty and Rob had during this experiment.

Rob then shared, “It relates to floundering time.   We found that even among the engineers, no one appreciated the value of one hour of production time. We asked a group of operators what an hour of production was worth and the figures ranged from $50 to $500 dollars. ACME runs two shifts at 30% uptime, that’s about 1500 hrs per year. Our typical line produces $30 million per year, that’s $20,000 per production hour. When we told the operators this, floundering time dropped significantly.”

Patty added, “The other thing we saw is that a “watchdog” is needed. If someone isn’t constantly watching things, floundering and assist times will go up. Since productivity is doubled with a high uptime line, the added cost of a watchdog is insignificant.”

Epilogue: The Sixty Minutes Segment was a great success. Patty was made Director of Corporate Productivity, but was also asked to manage Pete, who would take over her old group. No one seemed to worry that Patty was Rob’s boss, except maybe Rob!

Over the past few years, I have been forced to come to terms with my current (and ever-growing) knowledge of “things”. It is easy to become overwhelmed by the engineering veterans who have minds swollen with information following their decades of professional exposure. The key is to admit what you do not know so that you can learn from their explanation, and then chime in when your own expertise fits and appears helpful.

I am not an expert of all “things.” In fact, I am so terrible at Jeopardy that my husband has developed his own character skit of me “playing” the show (and losing miserably) from my living room couch as he listens in humor from the kitchen. I am an expert in some things though, and these are what I highlight in my thermal blog. 

This is why I am so excited to see a fellow engineer starting his own thermal blog!! Highlighting his expertise in the thermal benefits of AlSiC, Mark Occhionero describes the usefulness of this material in various applications such as hermetic packages, baseplates for power modules, and lids for microprocessors. 

AlSiC materials have great thermal conductivity and the ability to shift CTE based on the amount of SiC filler used. This allows for CTE matching of lids to dies, and packages. With CTE-matched substrates, high reliability soldering for bonding and thermal interconnections is a breeze!!

剛剛看見一篇挺有意思的文章，標題是“全球LED三大陣營比較及廠商排名”，不禁讓我想起最近確實有更多的客戶問起關於LED的封裝和散熱材料了。

除了傳統用的焊接材料(soldering material)外，最近的好些客戶都問到關於散熱方面的材料，主要是針對高功率，高亮度(High Power High Brightness HP HB)的LED應用。傳統的硅膠(thermal grease)因爲其化學特性，導熱率比較低，而且容易在界面中移動，不能使接觸面都均勻導熱。最重要的是，隨著時間的流逝，硅膠的導熱性能會越來越差，所以現在越來越多的客戶在尋求更好的解決方案。

Indium公司的散熱界面材料（Thermal Interface Materials TIM）， 都是使用導熱係數比較高的金屬/合金，加上特殊的表面處理后，能更完整均勻地接觸導熱界面。而且即使隨著時間流逝，金屬的TIM的導熱性能也能保持穩定。

Indium公司還特意推出的網上的購買，為各種學校/機構/小量使用購買者提供方便。

Cheers!

Image: Indium Corporation.

Folks,

The adventures of Patty and Rob continue........

 “No way Rob. I can’t buy this one,” shouted Phil.

“I’m telling you I did all of the calculations. I know it can work,” Rob shot back.

“No way! You’ve been hanging around The Professor too long,” Phil continued.

“Guys, you’re not arguing again are you?” Patty said as she approached the lunch table.

“Your hubby’s gone crazy Patty, why don’t you trade him in for me?” Phil teased.

Why? Is he crazy? asked Patty.

“He thinks that, if we can get uptime high enough here in the USA, we can compete with assemblers in low wage countries. He’s gone too far this time,” answered Phil.

“Hear me out,” responded Rob. “Our uptime is about 30% on our lines. Patty and I made some measurements in China and uptime there is about the same. I did some calculations with ProfitPro and I’m convince that if we can get our uptime to greater than 60% we can compete, even if they pay only $0.75/hr vs our $12.50,” Rob finished.

Rob showed the ProfitPro output and sure enough the numbers didn’t lie.

Jan Curtis chimed in, “But Rob, that is theoretical. Realities might set in that will cause unforeseen problems.”

Phil agreed, “The only way to prove it is to do it.”

“You’re right,” said Patty, “Let’s do it!”

“Whoa girl! How can we do it?" asked Rob.

“Let’s develop a plan and go to Sam the GM and ask if we can do it,” was Patty’s answer.

All agreed it was a gutsy move, but worthy, and the only way to prove the point one way or the other.

So, Patty and Rob made an appointment with Sam Watkins, the site GM. They were admittedly a little nervous about the meeting. They both agreed that Rob should speak since it was his idea.

“To what do I owe the honor of a meeting with our recently married superstars?” Sam cheerfully greeted them at their meeting.

Rob explained their idea and showed Sam the ProfitPro output. He then requested that they be allowed to manage two assembly lines at ACME to show if increasing uptime to 60% was possible.

“So basically you are asking me for permission to improve our uptime on two lines to help us make a lot more money?” Sam asked. “Do you have a plan?” he continued.

Rob and Patty proceeded to show Sam their plan, and the two assembly lines on which they hoped to implement it.

Is it possible to pay US-type wages and compete with low wage countries? Will Patty and Rob be successful? Stay tuned for the results.

Folks,

Patty and Rob return from their honeymoon.......

Patty had just finished some emails and was ready to head off to meet Rob and some of their buddies for lunch. When she and Rob returned from China a month ago, Sam, the site GM, told both of them he was giving them an extra week of vacation for their honeymoon. Their China trip had been an unqualified success in helping the China teams achieve more productivity and higher yields. Sam had received numerous positive reports from the Chinese managers involved. There were several requests to have Patty and Rob stay a year in China to help with the many process issues that the China team has. Fat chance of that happening, Sam needed Patty and Rob here! Sam also mentioned that he knew that the trip was a little stressful coming so close to their wedding, so the extra week was ACME’s gift to the young couple for their sacrifices.

The wedding went off without a hitch. Patty was touched at how choked up her dad was in “giving her away.” The weeding reminded Rob and Patty how close they were to their parents. They both agreed that the support of their parents was crucial in any success that they had in life.

For their honeymoon they decided to tour France, Italy, and Germany. Rob was really proud that he handled the languages a little better than she did. Of all the things that they saw, they were most impressed with Pompeii. Because the city was covered in hot ash in a matter of moments, it was as if Pompeii was frozen in 70AD.  Visiting Pompeii was like stepping back into the time of the Caesars.

Truth be told, Patty was happy things were back to “normal.” It was pleasant to have their working schedule and to go home to their apartment at night. A couple nights a week, and most Saturdays and Sundays, she and Rob played golf. He had improved somewhat and she was a little annoyed that so far this year he had beaten her more than half of the time….and yes, he was rubbing it in.

As Patty approached the cafeteria she heard a friendly but heated discussion.

“No way can you evaluate an assembly company with just 10 questions,” Phil Anderson stated emphatically.

“I’m really convinced we can, I’ve thought it through a lot,” responded Rob.

“What’s the spirited debate about?" asked Patty as she sat down.

“Rob thinks you can evaluate an assembly company by asking a lead process engineer only 10 questions. Phil thinks he’s nuts,” responded Patty’s best friend Jan Curtis.

“I’ve thought about this quite a bit,” said Rob. “I’ve just finished reading Malcolm Gladwell’s ‘Blink.’”  “Gladwell claims that often the best judgments can be made quickly with just a sampling of data,” Rob went on.

“Be specific,” challenged Phil.

“OK, I actually developed 10 proposed questions to evaluate a assembler, let me list them and then defend them. Maybe you guys have better ones,” said Rob. 

Patty thought, as she heard this, that it was good news that ACME was looking to buy more assembly companies to handle their ever increasing workload……not like AJAX that was laying folks off.

Rob had come prepared, he actually had some print outs. His ten questions were:

1.      What is the composition of SAC305?

2.      What are tin whiskers?

3.      In a stencil aperture, what is the area ratio?

4.      What is an approximate peak temperature for a reflow oven in lead-free assembly?

5.      A board is inspected after wave soldering and one lead is not soldered to the board. The board is run through the wave solder machine again and has the same defect on the same lead. What is the most likely cause of the defect?

a.       The solder temperature is too low.

b.      The pad on the board is oxidized.

c.       The preheat temperature is too high.

6.       What are local fiducials on a PWB for?

7.       What does thixotropic mean in regard to solder pastes?

8.       A chip shooter places passives at a rate of 36,000 per hour. It is placing 300 passives on a PWB, how many seconds will the chipshooter take to place the passives on one board?

9.       A reflow oven belt speed is 100 cm/min. The PWB is 40 cm long. What is the minimum cycle time that the oven can support?

10.   What is tombstoning?

“You have got to be kidding,” shouted Phil, “everyone will score 100% on that test.”

Jan chimed in, “I’m not so sure. We hang around people all day who study this stuff. I’m not sure the typical process ‘engineers’ have enough time to study and learn new things…..Remember the 'water in the solder' and the 'isopropyl in solder paste' incidents?”

At this comment, Phil spit up his ice tea and started choking from laughter. One of their friends, Sally Herman, had been sent to a recently acquired company to help them with assembly process issues. One of the “process engineers” introduced himself by bragging that he was saving the company money by taking used, dried solder paste and mixing it with isopropyl alcohol so that the paste could be used again. Later in the day, the same chap shared that he thought he had a solution to the poor hole fill problem in lead-free wave soldering…….the solder was too thick, if it was mixed with water it would fill the holes better he opined.

Jan added, “As a minimum these questions act as a good screening process.”

Rob interjected, “That’s my point. I’m not saying this tells us everything, but you will agree that if a lead process engineer can’t handle these questions, it is unlikely he or she would be able to solve graping, or the head-in-pillow defect, right?"

All at the table murmured agreement.

“On second thought, maybe you have something here Rob," Phil said. “What do you propose as a passing score," he went on?

“Seventy percent,” Rob answered. 

Are Rob’s questions reasonable to evaluate an electronics assembler? What are the answers? Comment with your answers. Stay tuned to find out.

Cheers,

Dr. Ron

The image above is from: http://en.wikipedia.org/wiki/File:Blinkgla.jpg

As many of you know, I’m focused on applications for the solar industry and the semiconductor industry. In fact, many of the readers of this blog have spent a good amount of time working in both fields as well. Dr. Ernest Levine is just like us, except he makes these topics way more interesting to learn about than I have figured out how to do yet…

Whether you’re learning about semiconductors or solar cells for the first time, you’re planning on learning more, or maybe you just want a refresher course – check out one of these courses in October. The IC Fabrication Class is offered Oct. 12-13 and the Photovoltaic Class is offered Oct. 26-27.

Back in 2008 I attended the IC Fab class and interviewed Ernest to learn more: http://blogs.indium.com/blog/jim-hisert/0/0/ic-fab-course.

公司的Rick Short 分享了一篇很有意思的blog, 是說如何讓你的“公司博客(Corporate Blog)”上升一個台階的，作者是Alli.  http://blog.blogworldexpo.com/

這三點都很有啟發性，我也自我來一一對照檢查吧：

1．Event Coverage

Booths at an industry event for my video game blog

You need to be going to the major events in your niche. Not only is this a great way to network, but readers who can’t go to these event love to hear about the booths, keynotes, and after-parties. Make your readers feel like they were there too, and take advantage of the opportunity to be first to report on stories when industry news is announced at the events. Otherwise, you probably wouldn’t have the opportunity to be first. Remember, others in your industry are also posting about the event, so entice readers to check out your blog by putting a unique spin on every post you write.

行業的活動報道。確實啊，雖然參加展會有點勞頓，但是有哪一次相關的行業展會我沒有參加了，心中也會有點“淒淒然”的感覺；等參加的同事們回來了，我自己也爭看相片，到處打聽最新動向。如果在好的展會上，縱觀整個大行業的商傢，客戶，新產品新技術新動向，用心的話還是能認識不少人，了解不少東西的。將心比心，沒有去的同行們，也很希望了解最近最新的信息。那麽關於行業的主要活動的及時blog post, 也很會有吸引力的。想想以前自己post的展會blog, 雖然也寫了不少“大事件”， 如APEX, SMTAI, SNEC, Nepcon China,  但是起碼在及時性上，我應該還是有大大的空間要提高啊！ 

2．Reviews

Many new bloggers and even some established bloggers don’t do reviews simply because they aren’t offered products. While it is nice to get freebies, the lack thereof shouldn’t stop you from posting reviews on items and services you were going to buy anyway. Doing reviews is a great way to establish relationships with companies in your niche, and if you write a good piece, even if it isn’t positive, the company is more likely to contact you with free products in the future to review.

Don’t forget that you can ask for products to review, too. The worst a company can say is no, and many companies will gladly send you product samples in exchange for your promotion. All you have to do is ask. Going back to my previous point, events are a great place to ask for samples to review. Company employees are usually authorized to give away x-number of their products at industry events, so you can score some major swag in exchange for reviews if you just ask. It’s also a lot harder for people to say no to your face!

產品預告。這點我可做得不着調了。 雖然平時我有在blog裏面關注和介紹Indium的產品和新技術，但是沒怎麽介紹co-supplier的東西，像什麽printer, reflow oven,, stencil, clean water, component, 等等。根源在於自己的了解認識少，不懂也就寫不出（或者從來沒有想過要寫）東西了。下回展會上，我要更加用心，多了解了。其實競爭對少的產品，我們倒是沒有少關注。但這裡畢竟是公司博客，不適合寫。  

3．Personal Stories

Believe it or not, people really do want to hear about your life. Stick to topics related to your niche, but don’t be afraid to tell your readers about your day or share a story from your childhood. It makes us all feel more connected. Even if you have an “about” page that shares your blogging journey, dish a little from time to time to keep us interested. Remember, people don’t just visit your blog to get information; people visit your blog to get information from you. If we feel like we’re emotionally invested in your life, we’ll come back, the same way people watch soap operas every single day.

個人故事：從寫博客人的角度講，這是叫做“個性化personality”, 這也是Rick Short 很久以前寫博客“4P理論”(Passion, Points, Persistence, Personality)的最後一個。從讀者的角度講，我們每個人多多少少都有“好奇心”。 我喜歡在post後面加一個“PS:”，當作是題外話，也是和大家分享個人故事的小角落吧。正文後面的“PS”全稱應該是”Post Script”，哈哈，看來和這個”Personal Stories”不謀而合了。

Cheers!

Pic: Alli’s   http://blog.blogworldexpo.com/  “Booths at an industry event from my video game blog”

在表面貼裝技術(SMT, Surface Mount Technology)以前，主要流行的是波峰焊(Wave Soldering).   雖然現在大部分的電子產品焊接都是SMT，但是某些不需要微型化(miniaturization)的產品，如DVD播放機，還有波峰焊的低成本優勢，都是波峰焊技術至今還存在的主要原因。 Indium公司的資深顧問Dr. Ron Lasky曾經説道，波峰焊技術在我們的下一代，下下一代，都應該還存在的。

最近又有一個客戶和我們一起探討波峰焊助焊劑(wave flux)的殘留問題。他們使用的是免洗(no clean)助焊劑。正是因爲免洗，所以各種不同的助焊劑，有不同量的殘留。 而客戶的客戶，也在對殘留的多少有一定的疑問。 其實現在在IPC的規定中，沒有具體規定免洗波峰焊殘留的多少是符合要求的。 最後我們根據客戶對焊接外觀和可靠性的綜合要求，推薦了最適合的一款產品。

Cheers!

PS: 一些年長的客戶或是合作夥伴總是開玩笑說“我在這個行業工作的時間一定比你的年齡長。想當年手工焊接或是波峰焊的時候……”

Pic: http://enc.ic.polyu.edu.hk/Zhengde/z2003/ws/images/pic2.png

Folks,

Tin Whiskers (TW) continue to generate considerable interest. People often suggest that their risk is great and yet unknowable. RPN may help to clarify the TW risk. What is RPN? It is the risk priority number from failure mode and effect analysis.  As this link tells us:

A failure modes and effects analysis (FMEA), is a procedure in product development and operations management for analysis of potential failure modes within a system for classification by the severity and likelihood of the failures. A successful FMEA activity helps a team to identify potential failure modes based on past experience with similar products or processes, enabling the team to design those failures out of the system with the minimum of effort and resource expenditure, thereby reducing development time and costs. It is widely used in manufacturing industries in various phases of the product life cycle and is now increasingly finding use in the service industry.

RPN is an important part of FMEA. It is the product of three numbers that range from 1 to 10. The first number is the severity (S) of a possible fail. A “10” would be given if the failure injured someone, “7” would be assigned if the failure caused a high degree of customer dissatisfaction, whereas a “2” would be given if the failure has only minor negative effects.

The second number is occurrence (O) of a fail. The highest rating is a “10,” which would be a failure every day (reminds me of Windows ME!) or one fail in 3 events, whereas a “7” would be a failure every month or one in 100 events. A “2” is a six sigma fail rate.

The last number is detection (D) of a potential fail. A”10” would suggest that the detection of a potential fail is either not performed or not possible. A “7” is a manual detection approach that may not be reliable, whereas a “2” is 100% effective potential failure inspection.

So obviously a product with a RPN of 10x10x10 = 1000 is a disaster, its failure is dangerous, frequent and incapable of being detected beforehand. Industry rules of thumb suggest that and RPN of 200 needs to be addressed and an RPN of 75 is usually considered acceptable.

Let’s look at a “ball park” RPN for tin whiskers (TW). We will assume the application is a critical IC in a PC.  Let’s assume that a severity rating of “S” of 8 (failure renders the unit unfit for use) is reasonable. TW are hard to inspect for future fails, so detection, “D,” could be as high as a 10. At this point we are at 8 times 10 equals 80 for both. A bad start.

Occurrence , “O” for TW failure modes is dramatically different. When trying to assess the occurrence of TW fails, one is often directed to NASA’s web page . Many reference this web site that lists a little more than a score of TW fails. What escapes me is that people don’t seem to appreciate the rarity of less than 100 fails in decades of data collection. Surely TW fails are not common. I could find no report of a failure of a RoHS compliant product anywhere on the internet. So it would be hard to rate “O” any higher than a “2.” I suspect that the reason few TW fails have apparently occurred is due to TW mitigation techniques that are widely practiced.

I would expect that “modern” process defects like the head-in-pillow or graping defects could have a much higher RPN than TW, if assembled without proper process controls and materials. However, there is little need to worry about these defects either, if you use the right solder paste and practice some assembly process precautions.

I’ve been pulling some products together for the InterSolar tradeshow in July, and a thought occurred to me: “these tabbing ribbon kits for solar panel assembly are so interesting, I know someone at the show is going to want one”. If you’ve been in a booth at a tradeshow before it’s probably happened to you too – someone may have asked you for one of your display items, last pieces of literature, or maybe some ancillary equipment that you had at your booth. For argument sake, let’s say it’s the only sample of a hot new product at your booth, and the customer wants to purchase it with cash and walk away with it on the spot. (Equipment guys have been known to frequently sell the equipment they had brought to the show, but they send the machine after the show is over.) So what do you do if someone wants to purchase the item you have on display?   

A second question from a different perspective: as a customer, how would you feel if the vendor wouldn’t sell that one display item that you’d like to leave the show with?

I’m really excited about a new option for those of us who are prototyping solar assemblies or evaluating new tabbing ribbon materials. I’ve been waiting for something like this – everything you need to solder solar cells together in one package. The turn around time is key too – you may recall an older post where I learned how quickly these materials shipped.

On the website where these kits are offered, the description reads:

“Tabbing ribbon kits come with everything you need to evaluate how Indium Corporation materials will work with your solar cells and assembly process. The kits can be used to:
- Evaluate which tabbing ribbon size is best for your design
- Determine which flux is best for your operation
- Experiment with new solder coating alloys
- Assemble a few solar panels”

The tabbing ribbon kits come in 3 flavors:

- Standard Sn/Pb/Ag (62Sn/36Pb/2Ag)

- Pb-Free (96Sn/4Ag)

- Low Temp Pb-Free (58Bi/42Sn)

I have a feeling the Low Temp Pb-Free kits are really going to be the most popular of the 3 that are offered though. Application temperature ranges will determine which kit to use, but all three versions of the kits are said to offer similar base copper sizes and tolerances:
“The ribbon itself is industry standard CDA 110 (99.9% Cu) core flat wire, coated with a precisely controlled layer of solder. Each ribbon is manufactured using our proprietary softening process so you can increase the yield of your stringing process.” Basically, this means that the softer tabbing ribbon will help eliminate the breakage of thinned cells during the heating/cooling cycle.

It also includes some matching bus ribbon to complete your panel build. If you’re trying to find the right flux, this kit serves dually as a flux evaluation kit as well. The kit is loaded with VOC-Free flux, rosin-based flux, and resin-based tabbing fluxes. I prefer GS-5454 as a flux for most tabbing operations, but you can see how the others stack up as well.

Let me know how you like the kit after you try it out!

~Jim

(jhisert@indium.com)

最近有越來越多的客戶問到金錫焊接材料。這些客戶中，多數是做航空航天製造的，醫療器械/零件組裝製造的，或是軍用製造的；它們都對成品的可靠性要求十分高(High Reliability).

金錫電子焊接材料(AuSn Soldering Materials)，通常使用共晶合金80%金20%錫，熔點溫度是280⁰C.  這種合金有很強的焊接強度，抗腐蝕，而且熱傳導效能很好(high thermal conductivity).   如果客戶的板子是厚金鍍層，或是要和貴金屬焊接在一起的，又或有分溫度階梯焊接需求的(step soldering)，金錫焊接材料都是很好的選擇。

 金錫焊接材料焊接材料可以做成焊綫(wire)，泊帶(ribbon)，各種形狀和尺寸的焊片(preform)，或是焊錫膏(solder paste)。Indium公司有專門介紹金錫焊接材料的blog，歡迎參閲。

Cheers!

Pic: Indium Corporation

Indium Corporation has won the Innova Award for Best Technology for its Heat-Spring^® metallic thermal interface material (TIM).

Heat-Spring is a clean, high-performance thermal solution for the increasing demands of high brightness LEDs. It is a compressible metal foil with proven performance in such demanding environments as electronics, aerospace, and power devices.

The compressible TIM provides low thermal resistance as a result of its high thermal conductivity (86W/m-K) and its ability to conform intimately to interface surfaces.

Unlike other thermal interface materials, such as thermal grease that bakes out, dries out, or pumps out during use, the thermal resistance of the Heat-Spring continues to improve with time and power cycling.

According to Jordan Ross, Market Manager for Thermal Materials, “Indium Corporation is honored to be recognized with the Innova Award for our patented Heat-Spring product. With its patented compressible interface design, Heat-Spring provides optimized surface contact, superior thermal conductivity, and enhanced heat flow.”

Sponsored by LED Journal, the Innova Awards feature leading companies within the LED market which have shown, through their products and services, the most innovative and advanced technology breakthroughs in LEDs. The award is designed to recognize companies each year for industry leadership, product development excellence, best new technology, and outstanding LED applications, which will eventually lead to the widespread adoption of LED technology in the marketplace.

上周三，Indium公司參加了SMTA 伯特蘭(Portland OR)地區的供應商展日。
 

展會前後總共6小時，其中有三場行業專家的演講。這也很像是一次非正式的大聚會，總共有60多人參加，基本上是Oregon州SMT行業相關的人員。

SMTA全稱是Surface Mount Technology Association，在全世界各地都有分部（chapter）.  Oregon Chapter是美國區很活躍的分部之一。幾年前，SMTA在中國也設立了分部。

Cheers!

Pic: Anny Zhang with Indium Corporation

Patty, Rob, and The Professor finished their tasks in Shenzen and were flying to Shanghai for their last set of challenges in electronics assembly.  Then they would head back to the US, Rob and Patty being only a week away from their wedding day.

As usual Rob, conked out as soon as the plane lifted off. Surprisingly, The Professor also drifted off to sleep. Patty was too excited to sleep. Rob’s mother had given her and Rob their wedding presents early … an iPad  for each. They decided to bring only one laptop and one iPad. Patty was a little nervous about using the iPad for presentations but it worked quite well. She was still surprised that the iPad did not have a USB port. The Professor also gave each of them an early wedding present, a Pickett slide rule for Rob and a K&E slide rule for her. She must be the only person in the world right now that was watching a movie on an iPad and solving a math problem with a slide rule!

True to form, The Professor was passionate about how learning to use a slide rule helped improve a person's innate math ability. He showed Patty and Rob how to use them and gave them several assignments. Rob was better with his slide rule than Patty due to the amount of “one on one” time he had with The Professor. She had to admit that using the “slip stick” gave one more of a feel for calculations and it was consistent with one of The Professor’s adages: “Always know approximately what the answer to a calculation should be…..it will help you to avoid errors."

In addition to the iPad and slide rule, Patty was excited to be going to Shanghai at the time of the World Expo 2010. Our trio had scheduled some time at the expo into their busy schedule.

Their plan was for Rob and The Professor to work on some productivity issues and for Patty to take on some of the process materials related problems. The three of them again met with the site GM for ACME’s newly acquired plant in Shanghai, a Mr. Wong. Wong was relieved to find that they all spoke Mandarin, as his English was a little rough. When The Professor addressed him in excellent Shanghainese, everyone was speechless. Patty was determined to ask him about this later. No American spoke Mandarin, Cantonese, and Shanghainese!

They again agreed to stick to Mandarin. Patty headed out to the line, accompanied by a young Chinese engineer, Zhou Chang, who seemed to be taking more interest in her than expected. She tried to make her engagement ring visible, but she wasn’t sure the he knew of the significance of it. When she got to the line that was experiencing yield problems, the Engineering Manager, Fei Ding, met her. He showed her some of the fails and she quickly identified the head-in-pillow (HIP) defect as the likely culprit. After investigating some more fails, looking at stencil printing, some of the BGA components, and component placement, she asked Zhou Chang what spec was used to thermal profile the line.

“I don’t understand what you mean,” Zhou said in Mandarin.

“How do you determine what the reflow profile should be?”  Patty responded.

With more discussion, Patty determined that they had one profile for all products! Fortunately most of the products were of similar, small thermal mass.

“What solder paste do you use for this line?", Patty asked.

The embarrassed silence suggested that Zhou did not know! They grabbed a tube and Patty was relieved to see that it was one of her favor solder pastes. Since profiling was so rarely performed, Patty and Zhou had to go to another part of the complex almost a mile away to find a reflow profiling unit. After taking the profile, the likely solution appeared. The 11 zone oven was very long and the reflow profile had a long thermal  “soak” before the temperature went above liquidus. This long soak probably exhausted the flux, so that when the PWB went above liquidus, there was little flux left, resulting in oxidation and poor reflow.

All during their time together she had mentioned that her fiancé Rob was here, with her on the trip. This information seemed to do the trick.

“Zhou, why don’t you look up the solder paste spec on the web and then set up the right type reflow profile,” Patty suggested.

It was clear that Zhou was troubled. It became obvious to Patty that Zhou did not know how to profile a reflow oven. Patty set about working with Zhou to accomplish this mission. Within an hour they had re-profiled the oven and, over the next two hours, 300 PCBs were manufactured with the yield improved to 95%.

Patty asked Fei if she could give a brief presentation on the head-in-pillow defect to his team and he cheerfully agreed. Fortunately for Patty, her friend Mario Scalzo had given her his presentation that he gave at APEX 2010 on HIP (head-in-pillow). Patty always enjoyed visiting Mario in Utica, NY, as he always knew the best restaurants in town.

Her major points were:

HIP is caused by the failure of the BGA sphere to reflow with the solder paste. There are 3 major reasons for HIP:

1.       Supplier Issues

a.       Solder BGA sphere oxidation

b.      Silver segregation to the BGA sphere surface

2.       Process Issues

a.       Stencil Printing

                                                               i.      Registration accuracy

                                                             ii.      Insufficient solder paste

b.      Component Placement

                                                               i.      Off pad

                                                             ii.      Out of plane

                                                            iii.      Non optimum pressure

c.       Reflow

                                                               i.      Inappropriate reflow profile

                                                             ii.      Flux exhaustion

                                                            iii.      PWB warpage

3.       Material Issues

a.       Poor solder paste transfer efficiency

b.      Insufficient solder flux oxidation barrier

c.      Solder paste slump

d.      PWB or BGA warpage

Patty went on to say that she had investigated all of these issues with Zhou, and that the reflow profile was not optimum as the very long soak time had exhausted the flux. The other possible issues in the list did not seem to be a concern.

At the end of the day Patty, Rob, and The Professor met at the GM’s office to leave together for dinner and the Expo. Patty had to ask, “Professor, how can you possible know Mandarin, Cantonese, and Shanghainese?”

“Actually I speak Min reasonably well too,” he replied.

“How can this be?", Rob inquired.

“Mother and father were missionaries with Wycliffe Bible Translators,” The Professor answered.

“I grew about around many languages during my youth. Mother and father speak more than I do,” he finished.

Patty went on to tell about the interest that Zhou Chang seemed to have in her, and how she had to discourage him.

“The burdens of being a beautiful young woman,” Rob teased.

Patty elbowed him, but they all left the taxi laughing as they headed for a restaurant near the Expo.

Best Wishes,

Dr. Ron 

The Shanghai, slide rule, and HIP images are from: 

http://pool14.files.wordpress.com/2008/12/shanghai_skyline_g.jpg

http://www.hpmuseum.org/powerlog.jpg

http://ppsimanufacturing.files.wordpress.com/2010/03/bga100.gif