Dr. Lasky’s Blog
Recent Entries
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Counterfeit Component Concern Goes Mainstream
October 7th, 2008
Folks,
It seems that there is several year lag before many of "our"* concerns become mainstream. As an example, in December of 2005, I posted a note Re discussions I had with PC Magazine's famous "Cranky Geek" John Dvorak. As of that late date, a well informed chap like he, was not aware of RoHS. Now PC Magazine gives a green rating to all products Re their RoHS compliance and energy usage.
Also in late 2005 I discussed counterfeit components. The October 13, 2008 issue of Business Week has an article "Dangerous Fakes" . This article discusses the growing threat to the United States' military hardware from counterfeit components. Perhaps the most unsettling point in the article, was how easy it is for an inexperienced person to obtain a government supplier code and supply the pentagon with parts obtained through searches on the internet. The supplier is often unaware that they are occasionally supplying counterfeit components.
Many have worried about reliability of RoHS compliant electronics products. I believe that the increasing numbers of counterfeit components are creating a reliability risk that will dwarf any concerns about RoHS reliability.
Cheers,
Dr. Ron
* Our = those in the electronic assembly industry
The image is of a stealth fighter from http://timm84.files.wordpress.com/2008/06/stealth-bomber.jpg. By using this image, I'm not suggesting that this fighter has any counterfeit components in it.
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A Challenge of 01005 Passive Assembly
September 23rd, 2008
Folks,
Last week Indium Corp held its annual Technology Summit. There were many excellent technical presentations. Chris Anglin's brought out some information I would like to share with you.
In stencil printing of fine features, the area ratio (AR) of a stencil aperture is an important metric. AR is defined by the area of the stencil opening divided by the area of the side walls. For a circular aperture this is:
AR = Pi * r2 / (2Pi * r * t ) = r /2t or D / 4t, where r is the aperture radius and t the stencil thickness (D = 2r).
Experience has shown that for successful printing, AR should be >0.66. Chris pointed out that successful printing is more dependent on consistancy (small standard deviation) among the printed solder paste deposits than a transfer efficiency (TE) close to one. Transfer efficiency is the ratio of the volume of the printed deposit divided by the volume of the aperture. In other words, you can have successful printed with a TE of say 0.5 as long as the variation among the deposits is small.
What was most surprising to me was the AR of common objects. Chris used this approach to convey the concept in terms of objects that we can relate to. The can of Bumble Bee tuna in the photo has an AR of only 0.49! Intuitively, I think most of us would have thought that an aperture with the dimension ratios of a tuna can would be good for printing. Chris points out that it is low by almost 20%.
AR shows the extreme challenge of 01005 printing. To print for these small passives, the aperture will need to be about 6 mils. To have an AR of = 0.66, the stencil thickness must be t = D/ (4*0.66) = 6/(4*0.66)= 2.3 mils. Since most other devices would might need a 4 mil or thicker stencil to obtain enough solder to make a good joint, a step stencil or two printing steps may be needed for successful 01005 assembly.
And I'll bet people are working on a developing an 0050025 passive. Yikes!
Cheers,
Dr. Ron
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Another SMTA Process Certification Question
September 13th, 2008
Folks,
The following question is one that students in SMTA Processes certification struggle with. Jim Hall and I are always a little surprised, as it is taught in the refresher class quite thoroughly and seems straight forward. See how you do. I will post the solution in a few days.
BTW, I am teaching a "Pre-Certification Class" to review the concepts required to pass the SMTA certification test on September 16, 2008 at the Concourse Hotel at the Columbus, OH airport. Come and join us if you are in the area.
The question follows:
A 7 zone oven has a heated tunnel length of 250 cm. A 20 cm PCB needs to be in the heated part of the oven for 4 minutes. What is the maximum throughput in PCBs per minute that this oven can support?
The photo is of several Speedline ovens and wavesolder machines.
Cheers,
Dr. Ron
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Are You Ready for SMTA Process Engineer Certification (With Solution Update)
August 24th, 2008
Folks,
Since 2002 SMTA has had an SMT Process Engineer Certification Program that was developed by Jim Hall, Phil Zarrow and me. Some folks are a little nervous about taking the workshop and exam. In light of this concern, I have been asked by the Ohio SMTA chapter to give a 5 hour workshop on the types of problems one would be expected to solve. I have proposed a list of problems to be covered in the workshop. Here is a typical one that I might use. See if you can do it.
Component placement is the limiting process in an SMT line for throughput. Throughput (cycle time) is now one board every 50 seconds, when the line is running. There is one chipshooter (CS) and one flexible placer (FP). The bill of material (BOM) is 300 passives, 24 SICs (simple ICs), 8 CICs (complex ICs). The chipshooter is taking 50 seconds and the flex placer 20 seconds. All passives are being placed by the CS. The FP places CICs in one second. It places passives and SICs at the same rate.
1. Maximum throughput will be obtained when the CS and FP take the same amount of time. This can be accomplished by moving passives from the CS to the FP for placement.
a. What is the minimum cycle time if the line is balanced?
b. How many passives were moved to the FP to achieve this cycle time?Note: We assume all other processes can keep up with the new and improved cycle time.I will publish the solution in a few days. I expect to be giving this workshop quite frequently in the future.Solution:The FP takes 20 seconds to place the SICs and the CICs. The 8 CICs take 8 seconds, so the 24 SICs must take 12 seconds. Hence, the placement rate for SICs is 2 per second. The CS places 300 passives in 50 seconds, so it places 6 passives a second. Since the CS takes 50 seconds, to balance the line we must move passives to the FP. Our goal is that the time spent by the CS is the same as the FP. Let us assume that the number of passives we have to move to the CS is x, then time balancing can be expressed by the equation:tcs = (300 -x)/ 6 sec = tfp = 20 secs + x/2, solving for x: 300 - x = 120 +3x => 4x = 180 => x = 45So 45 passives are moved from the CS to the FP, hence the cycle time is now: (300 -45)/6 = 42.5 sec.The solution was quickly verified by LineSimulator(TM) software I developed. If anyone would like a copy of this software tool, send me a note at RLasky@indium.com.Cheers,Dr. Ron -
Meet the Bloggers at SMTAI
August 19th, 2008
Folks,
Well, I arrived at SMTAI a few days early to take my wife, daughter and two granddaughters to Disney World. We averaged 7 miles of walking a day, Friday through Sunday. My 2 year old and 4 year old granddaughters had a great time. However, we learned that the 3D movie, "Honey I Shrunk the Audience" is a little too scary for a 2 - 4 year old.
It ends up that mid August is a good time to visit DW, as many families have stopped coming as they prepare for their youngsters to attend school.
The weather was also mild (i.e not extremely hot and humid) as a prelude to tropical storm Fay. So my family had 4 good days of touring, before the strong rains came.
The Show? The tech sessions and workshops seemed quite well attended on Sunday-Tues. Hot topics: the need for recycling driving "design for disassembly, counterfeit components, and conversion of lead-free alloys to a few standards seemed of interest to many.
Sadly, it looks Fay has reduced traffic on the show floor as I write this note on Tues afternoon.
If you are here and can make it, join us at our "Meet the Bloggers" meeting on Wednesday, August 20 at 11AM at Indium's booth # 517. It should be fun. Five of Indium's bloggers will be there.
Cheers,
Dr. Ron
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Alloy Density Calculator Goes Live
August 8th, 2008
Folks,
Over the past few years I have been surprised at the interest in the Excel based alloy density calculator that I developed. Thanks for your interest!
In light of this interest, team Indium suggested that it be made available on the web for all to use. Find it here.
I have written some other software that I will be discussing in future posts. One even perfroms the calculations to time balance the component placement machines on a line. Another matches the solder paste spec to the reflow profile. Stay tuned.
Cheers,
Dr. Ron
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Dr. Ron Gets Second Eagle in Golf in a Year
August 4th, 2008
Folks,
Lest I seem braggy, one thing must be made clear. In general I have never been a good athlete. I can not get my body coordinated enough to make a "layup" in basketball, and I was never really a good baseball or football player. I am the most inefficient swimmer on earth, being able to swim only 50 yards, before I poop out (and I'm not in too bad shape). I'm fair at tennis and racquet ball.
However, in addition to being quite fit (30 push ups at 61 years old), I can do three sports things relatively well: pull back a strong long bow, throw a frisbee far and play golf relatively well (high 70s to mid 80s most days).
Last week at the Country Club of New Hampshire, on the par 5 8th hole, I got my second eagle in less than a year. Last year I bagged one at Woodstock Country Club's very short par 5 10th hole. Last week's eagle (a 3 on a par 5) was rewarding in that I hit a 260 yard drive, a 5 wood from 225 yards to 10 feet from the hole and sunk the putt.
Someone commented in Golf Digest about a year a go, that golf was one of the few "egalitarian" sports in that for a short time a so so golfer could outdo a champ. Maybe any of us could make a put that Tiger misses, or likely out do Phil Mickelson's 9 in the past US Open. Whereas few of us could survive even a few seconds with Roger Federer (Tennis) or an NBA basketball player.
But on the 8th hole last week, in my mind at least, a recovered Tiger, Phil and Adam Scott were in my foursome, they all got birdies and I got the lone eagle. Don't be mean.....let me dream!
PS: But my final score was an 80 and I'm sure the rest of my foursome described above would have shot around 65.
Cheers,
Dr. Ron
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Is REACH Going to Be RoHS Cubed?
July 28th, 2008
Folks,
Peg writes:
If the RoHS sweep does not scare you as a company, just wait for the REACH sweeps and SVHC list.
RoHS is the tip of the iceberg and paved the way for the much larger REACH program that will cost companies billions, put at risk companies IP.
REACH is being marketed at a greener way to test for substances and the goal is to combine all substances into one massive database so that we can “Share” in the knowledge of how substances effect our environment. However as this is generated so to is the SVHC (Substances of Very High Concern) that list those substances that the EU feels is not in the best interest of the environment (or better way to state it is the list that EU can apply a substance Tariff that will allow for the continued import.) Also a good way to get information on companies IP.
So be ready to have your checkbook ready, as it is free this year to register what it is you ship into the EU and at what tonnage you ship it. You can bet there will be a yearly bill sent to you and your company for the importing of that substance.
It is hard to not be sympathetic to Peg's concerns, where RoHS is only six pages and controls only 6 substances, REACH is over 800 pages and some suggest will cover up to 30,000 compounds. Here are some key REACH points:
- Its focus is for companies that export chemicals/materials to the EU, as opposed to electronics products.
- Companys that export more than 1 ton of materail to the EU need to pre-register the materials now. The deadline is November 30th.
- You will then be assgned to participate in Substance Information Exchange Forum (SIEF) in which you will exchange information with others and perhaps perfrom experiments to demonstrate the safety of a substance.
- Substances of Very High Concern (SVHC) will get the immediated attendion of the EU.
- If your vendors supply you with a chemical that you incorporate into one of your materials, they must pre-register their chemical, to assure that you can use it.
- Becasue of the mandated participation in SIEFs IP may be at risk.
All in all Yikes!
Cheers,
Dr. Ron -
Lead-Free Solder has Secondary or Less Impact on Tin Consumption
July 16th, 2008
Folks,
A few years ago, Prismark estimated that the world electronics usage of lead was 18,500 tons per year. Assume most solder at the time was tin-lead eutectic (63% tin, 37% solder) this would equate to about 50,000 tons per year of solder used in electronics and 31,500 tons of this solder being tin. With the advent of lead free soldering, using say SAC305 (96.5% tin, 3.0% silver and 0.5% copper), most folks would suggest that .965 x 50,000 = 48,250 tons of tin are now being used, an increase of about 17,000 tons of tin. However, solder is used by volume not weight, assuming a leaded and lead-free solder joint are of the same size (i.e. volume). Since the density of tin-lead eutectic solder is 8.4 g/cc and the density of SAC305 is 7.36 g/cc, a given lead-free solder joint weighs only 87.6% (100 x 7.38/8.4) of a tin-lead joint.
Considering this argument, our 50,000 tons of solder of solder per year, requires only 50,000 x 0.876 = 43,806 tons of SAC305 lead-free solder to make the same solder joint volume. This amount of SAC solder contains 42,276 tons of tin, an increase of less than 11,000 tons of tin over using tin-lead solder. When one considers that for wave soldering, the lack of wetting of lead-free solder further reduces the volume of solder used, the actual increase in tin usage may be < 10,000 tons.
The United States Geological Survey estimates that about 300,000 tons of tin are mined each year. So the increased use of tin for lead-free is about 3-4% of that mined. This figure matches well with the USGS’s statement that tin usage in the US rose 2% in 2007. However, with numbers this small it is hard to support any trend.
I thought these numbers might be helpful in understanding the impact of lead-free soldering on tin consumption. Many had assumed that lead-free would dramatically impact tin supplies, when in truth lead-free solder has only a secondary or tertiary impact on tin usage.
The photo is an image of a lead-free through-hole solder joint cross-section that my Indium colleagues took. It is likely that the equivalent tin-lead joint would have even more solder volume as discussed above.
Cheers,
Dr. Ron -
Meet My Fellow Indium Bloggers at Semicon West
July 8th, 2008
Folks,
Indium Corporation's industry leading semiconductor bloggers are hosting a
Meet the Bloggers session on Tuesday, July 15, 2008 at Indium Corporation's
Semicon West exhibit, booth #7834,
from 2-3pm PST.
The technology experts will lead discussions on topics including:
* Flux deposit measurement using non-contact metrology
* Two upcoming white papers (currently under development):
* Wafer Flux Spin-Coating Topography
* Wafer-Level Flux Printing
Recent hot semiconductor blog topics, including:
* Semiconductor assembly materials
* Future trends in first- and second-level assembly
* Halogen-free semiconductor assembly materials
* Engineered solders in MEMS assembly
* Thermal interface issues
* Solar device assembly
Indium personnel who will be discussing these topics include Jim Hisert, Paul Socha , Fez Sayed, Dr.
Andy Mackie, and Rick Short.
All attendees are welcome to participate in, or observe, the session. Snacks
will be served, too!
Indium's blogs can be seen at www.indium.com/blogs
Stop by and see them if you are at the show!
Cheers,
Dr. Ron
Want to read more? Browse the archive of past entries.
This Week’s Quiz
- Solve for X
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Solution:
Reader Ranjiv got the solution right. Since x^x^x^x^x........... = 2, X^2 = 2 and X = sqrt 2 = 1.414...
This solution can seem incorrect if you take 1.414^1.414=1.6325 and then take 1.6325^1.414 =2 and then take 2^1.414 obviously > 2.
The correct way to check the solution is to take 1.414^1.414=1.6325 and then take 1.414^1.6235 and so forth, then the solution converges to 2.
Cheers,
Dr. Ron
Folks,
A little math puzzle from my eye doctor:
x^x^x^x^x........... = 2, solve for x
That is: x raised to the power of x raised to the power of x........an infinite number of times = 2.
Cheers,
DR
Sideblog
Quick notes of interest:
- Dr. Ron's SMT Article "Repeal RoHS Movement Emerges" Causes Furor
Folks,
I guess I have stirred up a hornet's nest. My article Repeal RoHS Movement Emerges in the September issue of SMT and has generated much interest. I have even been accused of being the only person in manufacturing that is "pro-lead free solder." Wow! I think the folks at Motorola that have manufactured 150 million cellular phones, that could not be assembled with leaded solder, must have hurt feelings. Truth is I don't think I am "pro-lead free solder," I believe that I am pro data driven decision making....the topic for a future posting.
These articles have also caused much discussion on IPC's TechNet and I'm told a few other places.
Anyway check these articles out. I respect those that disagree with my perspective and believe that only by sharing and learning can we progress.
Cheers,
Dr. Ron
- Dartmouth and SMT Magazine Unite in Six Sigma Effort
"He is probably the most influential American you never heard of. The "Father of West Point," "Father of Technology in the United States" and the founder of Thayer Academy in his native Braintree, Mass., Sylvanus Thayer arguably left a greater mark on our country than half of our Presidents. Without him, there might not have been a Grant, Lee, Pershing, MacArthur, Eisenhower, Patton or many other great leaders. Most of the early significant engineering projects in our country were led by students of his, most notably the Panama Canal and George Goethals. One of the last things Thayer did in his long and productive life was to found and endow the Thayer School of Engineering at his Alma Mater, Dartmouth College."
See how it all converges on SMT and six-sigma at the SMT Magazine website.
- Articles in SMT Magazine
SMT Magazine is a leader in delivering sound technical information regarding electronics assembly materials, processes, and technologies. For a list of many of my contributions to this magazine, please follow this link.
- Lasky in Print
If you're interested in reading some of my publications, you can find many available here.
