Posted by Chris Lopez on Wed, Jan 25, 2012 @ 12:00 AM
What do we mean by Thermal Management?
by Chris Lopez and James Forster
In trying to understand what thermal management might mean to others we decided to go-to-the-net and do what we all do every day – a Google search. The results were interesting and are the start of this discussion.
A Google search of “thermal management” produces more than 10 million hits. The first is an article on Wikipedia titled “Thermal management of electronic devices and systems”. See: http://en.wikipedia.org/wiki/Thermal_management_of_electronic_devices_and_systems
This was encouraging since it certainly seemed appropriate to the semiconductor industry. BUT…...
It’s an interesting article and discusses the issues of thermal management at the commercial product level but it does not mention thermal management during test which is the focus of our interest.
The second hit is a link to “Active Thermal Management”
http://www.activethermal.com/index.html
This certainly appeared interesting ….but it was a link to a web page which sold fans for audio-video equipment with information on fans for cooling commercial products. Hmmm … what about thermal management of electronic devices under test?
The third hit is a link to the Tessera web site – this certainly looks better.
http://www.tessera.com/technologies/microelectronics/Pages/thermalmanagement.aspx
There is some interesting data here – if you hover over the word “heat” at the beginning of the second paragraph you will see a pop up table which states that “heat is the number one cause of electronics failure” and shows a pie chart indicating that 55% of all failures in electronic devices are due to heat. Maximum junction temperatures for handheld, high performance and power electronics are given and range from 85 to 125°C.
The focus is on cooling laptops, again another consumer product, using a Tessera patented technology “Silent Air Cooling Technology”. Interesting technology but certainly not what we were thinking about.
Certainly the “hits” are associated with thermal management of electronic products and the language includes “thermal resistance” and other terminology we use every day but there is little on thermal management during test in the first couple of pages.
Changing the search to “thermal management during burn-in” produced a smaller listing of approximately 2 ½ million hits and the first hit was a link to a 2005 article in Chip Scale Review titled “Controlling Thermal Demands During IC Burn-in” and introduced WELLS’ iSocket™ technology. See:-
http://www.chipscalereview.com/issues/0505/article.php?type=feature&article=f2
That’s encouraging and the CSR article stated that:-
…integrated circuits with varying power densities create thermal management problems for backend engineering and production personnel.
The second hit is a link to a paper by Tadayon and others at Intel from the Q3, 2000 issue of the Intel Technology Journal.
ftp://download.intel.com/technology/itj/q32000/pdf/thermal.pdf
OK this is from 2000 and a lot has happened since then but the fundamental issues discussed are still pertinent. This is an interesting summary of the test processes used by Intel and the different thermal/temperature concerns and impact on costs during test, burn-in and sort. A statement in the introduction states that…
Based on the information provided above, it is clear that thermal management plays a very important role in the testing of microprocessors. Thus, it is necessary to control the die temperature during test where the goal is to gauge the device performance while keeping the test simple, efficient, and cost-effective. It is, however, extremely difficult to accurately control the temperature of the die since the power dissipation of logic devices can vary substantially during the test cycle.
Conversations with our customers about their concerns would certainly agree with the assessment that thermal management is an important aspect of testing. However the outlook is not as bleak as suggested by the last sentence. Cost effective solutions are available today for monitoring and controlling individual DUT temperature during test and/or burn-in and these will be introduced below and discussed in greater detail in subsequent blogs.
Returning to the first Google search hit, the article in Chip Scale Review….. This was, we believe, one of the first articles which stated the problem of the variation of DUT (Device Under Test) temperatures in an identical environment under identical test conditions. Figure 1 below is from that article and highlights the problem of temperature variation in test. It was also part of a presentation titled “A Cost Effective, Flexible Approach to Automated Thermal Control During Burn-In” By Chris Lopez and others at the BiTS Workshop in 2005. That presentation can be viewed at….
http://www.bitsworkshop.org/archive/archive2005/archive2005.htm
Figure 1: Graph showing the DUT junction temperature variation for the burn-in of identical devices in the same ambient conditions.
This graph was developed with Mike Noel and others at Freescale, Austin and shows the variation of the junction temperature of a number of devices from the same lot which were tested in an oven at the same time. In the test the oven temperature was increased in a step fashion – the black line in the graph - and the DUT temperature monitored. As the temperature of the oven was increased the DUT junction temperature increased – but due to small differences in the performance of each device the junction temperatures of each DUT was slightly different.
The objective of the test was to get the DUT junction temperature to 125°C. However because of the small differences in each device the measured DUT temperatures could vary as much as 40°C.
If the temperature variation during burn-in can vary as much as 40°C then this is not a process under control. It is this temperature variation which required an understanding of Thermal Management in burn-in and led to the development of WELLS’ proprietary iSocket™ technology or ATC “Active Thermal Control”.
Utilizing ATC the temperature during burn-in can be controlled within 2°C. Figure 2 shows the temperature variation of the same devices shown in figure 1 when iSocket™ technology is enabled. The devices can be monitored and controlled and the burn-in process brought under control.
Active thermal control will be the subject of a future blog which will describe the fundamentals of this approach and the details of the iSocket™ technology by WELLS-CTI.
So what is Thermal Management? It is a process or technology which enables the monitoring and controlling of each and every device under test so that each device is tested within specified temperature limits regardless of the DUT power or any variation or the conditions such as air flow rate or ambient temperature within the chamber.
Figure 2: Graph showing the DUT junction temperature variation for the burn-in of the same devices in figure 1 when iSocket™ Active Thermal Control is enabled.
References used in this article:
1) “Controlling Thermal Demands During IC Burn-in”, Chris Lopez and Mark Murdza, Chip Scale Review, May - June 2005
2) “Thermal Challenges During Microprocessor Testing”, Pooya Tadayon, Intel Technology Journal Q3, 2000, Intel Corporation.
3) “A Cost Effective, Flexible Approach to Automated Thermal Control During Burn-In”, Chris Lopez, Brian Denheyer, Michael Noel, and Don VanOverloop, BiTS Workshop, March 2005.
Posted by Matt Bergeron on Tue, Nov 22, 2011 @ 08:53 AM
We’ve had great success with customers who want innovative sockets that lower cost at the hand test/characterization stage. By molding a versatile socket body that can utilize a number of contact technologies (from elastomers to spring pins) we’ve been able to lower customer’s purchase prices by 60% - 70%. Our 890 series socket accommodates packages up to 15 x 15mm has a high force delivery system (up to 18Kg) with a Two Finger knob that is easy to operate even at high force. The lid assembly is easily removed and has an opening for thermal streams or equivalent air-flow temperature control systems. Ask WELLS-CTI for a quote utilizing the 890 series the next time you need a hand test socket.
Posted by Matt Bergeron on Thu, Nov 17, 2011 @ 10:56 AM
WELLS-CTI's sales and engineering efforts have focused heavily on Burn in sockets. While today we consider Burn in sockets a key product, we increasingly see a desire by our customers to have engineered solutions that focus on their particular test and thermal issues. Thermal control during the Qualification and Burn-in stages of test have become one of our forte’s with 
the introduction of our iSocket Technology in 2004 and later our Thermal Control Solutions (TCU) product line. Hand in hand with these products we’ve developed sockets that are geared towards these customer requirements as well – most notably our 89x sockets focused on Hand-Test/Characterization and our 86x sockets that have built in thermal control for iSocket and
MCC systems. Let us know if we can lend a hand in your difficult thermal control issues by contacting one of our sales team or WELLS-CTI directly.
Posted by Susan Campbell on Tue, Oct 18, 2011 @ 11:36 AM
WELLS-CTI is proud to be showcasing their products at LEDs 2011: Bringing Lighting to Life, be the fall’s leading lighting and LED event. Hundreds of lighting professionals will gather at the 12th installment of IntertechPira’s industry leading LEDs conference and sold-out exhibition to hear from Acuity, Cree, OSRAM, Philips and more. This year’s event will be held at the Hilton San Diego Resort & Spa from October 24-26, 2011 in San Diego, California, US.
WELLS-CTI will be showcasing their thermal testing expertise from heat sinks, air and liquid cooled systems, iSocket technology as well as custom thermal management solutions. Free exhibit passes for LEDs 2011 are available to meet with company representatives inSan Diego.
“Not all thermal testing can be provided by out of the box solutions. WELLS-CTI has a history of working with our customers to create custom solutions specific to their needs,” says Chris Lopez, WELLS-CTI Director of Applications Engineering.
LEDs 2011 will provide three full days of coverage of the latest technology, applications and end uses, luminaire and fixture design, and market expectations and analysis most relevant to the LEDs and lighting sectors. Organizations presenting at LEDs 2011 include ABILUX (Brazilian Lighting Industry Association), Acuity Brands Lighting , ASBAI (Brazilian Association for Architectural Lighting Designers), BetaLED, Cree, Digital Lumens, Excelitas Technologies, IMS Research, Inventronics, Intematix, io Lighting, Lithonia Lighting, Lighting Science Group, Lux Research, MSi, Nexxus Lighting, Nichia, Oree, OSRAM Sylvania, OSRAM Opto Semiconductors, Philips Lumileds Lighting, Prescolite, Switch Lighting, Traxon Technologies and the U.S Department of Energy.
WELLS-CTI is located in booth #47.
For more information on WELLS-CTI's LED Thermal Capabilities visit www.wellscti.com/thermal_led.html
For more information about LEDs 2011, visit www.ledsconference.com
Posted by Susan Campbell on Wed, Sep 28, 2011 @ 09:13 PM
WELLS-CTI has extended its reach from semiconductor test into the medical field by developing an interface contactor used in a medical diagnostic instrument. This multi-year development program, led by the Aubrey Group based in Irvine Ca., for one of their customers, resulted in the contactor used in a medical sensor system.
The medical instrument, which requires a stable temperature environment, uses microfluidics and electronic detection technologies to enable state of the art molecular diagnostics techniques to test a patient’s DNA sample.
The connector module, jointly developed by engineers at WELLS-CTI and Aubrey Group holds the disposable sample cassette while maintaining the temperature of 
the patient’s fluid sample and providing electrical and pneumatic interfaces. The thermal interface maintains the sample temperature as the pneumatic interface moves the fluid through a series of sensors. Thermal, pneumatic, and mechanical interfaces were developed by Aubrey Group. The contact system, developed by WELLS-CTI provides the electrical interconnect between the sensor systems PCB and the sample cassette allowing the molecular diagnostics of the sample.
“We used WELLS-CTI buckle-beam contact technology, originally developed for testing integrated circuits under harsh conditions. This technology was selected for its high density and reliable performance. Integration with the thermal, mechanical, and pneumatic interface requirements required joint engineering talents of both companies to bring the project to successful conclusion and subsequent quantity production”, says Milan Trcka, Chief Technology Officer, and Director of Electrical Engineering at Aubrey Group.
“We are very proud of our engineering and manufacturing team’s efforts to jointly design and build this critical part of this technologically advanced medical device,” says Matt Bergeron, WELLS-CTI President and CEO.
Contact WELLS-CTI for more information, 800.348.2505, www.wellscti.com
Posted by Chris Lopez on Thu, Sep 22, 2011 @ 11:39 AM
WELLS-CTI has seen increasing needs for high temperature, low cost burn in solutions at 225°C or greater for automotive, downhole and other extreme temperature applications. As a quick example, we have delivered a bench-top design utilizing our iSocket technology that integrated a QFP socket. One of the benefits of the bench-top solution is that the socket and electronics were not inside a chamber being exposed to 225°C - only the DUT was exposed to the temperature. Customers were able to utilize traditional low cost PCB materials and components since the ambient temperature was not high. In the past these processes required high cost ceramic PCB’s and high temperature rated components. Please contact us if you have a need for High Temperature Burn-in.
Posted by James Forster on Tue, Sep 13, 2011 @ 11:23 AM
By Chris Lopez and James Forster
It’s a hot one out there …. This summer has certainly seen record temperatures and the semiconductor industry continues to forecast increasing devices powers and temperatures. While the 1959 movie “Some Like it Hot” starring Marilyn Monroe is considered one of the greatest comedies ever (http://en.wikipedia.org/wiki/Some_Like_It_Hot) heat, or more precisely high temperatures, in the semiconductor world is a killer.
A number of sessions at the annual BiTS workshop have been dedicated to thermal issues and the measurement and control of DUT, Device Under Test, or junction temperatures. To those not familiar with the Burn-in process it is a strange test and against everything we would normally consider doing – place a perfectly good device into an oven and heat it to approximately 125°C. – Are you crazy? Yet that is exactly what we do but in some instances things can get out of control with disastrous consequences.
One of the early BiTS presentations by Mark Miller of AMD won the “Best Paper/Presentation in 2001 and has a great picture of what happens when things get out of control and go very very wrong ….. This is from Mark’s presentation titled "Next Generation Burn-in & Test System For Athlon Microprocessors: 'Hybrid Burn-in'" and shows the remains of a clamshell socket with the ceramic PGA still inside after a thermal runaway event.
http://www.bitsworkshop.org/archive/archive2001/2001s5.pdf
The next few blogs will discuss thermal issues in test and burn-in and describe how the industry has moved for static burn-in to active thermal control and how we can burn-in high power devices and prevent the kind of damage seen in Mark Millers picture.
Posted by Matt Bergeron on Wed, Aug 10, 2011 @ 01:21 PM
iSocket is an integrated solution which controls temperature of individual IC’s during test and burn-in. We’ve seen a number of customers convert to iSocket as speed, wattages and leakage increased. Once we developed our Oven Upgrade Module (OUM) more customers converted to iSocket because it enabled a simple and LOW COST way to update existing Burn in Systems to be able to actively thermally control devices during burn in. The system enables individual, stable device control at a preset temperature while actively monitoring and reporting individual DUTs and has the ability to shut down a device in the event of thermal runaway. The solution has also increased throughput by removal of pre-burn in power sorting, quicker ramping of temperature, etc. The OUM is self contained and allows the easy upgrade of an existing oven to support iSocket by providing all power and communications necessary and an easy USB connection to oven PC (or other PC) running iSocket Host software. We’re happy to review your requirements and supply a quote any time.
Posted by Matt Bergeron on Wed, Jul 27, 2011 @ 10:24 AM
WELLS-CTI has long carried the industry’s largest line of legacy test and burn in solutions and has multiple sizes of Carriers, Clips, and Contactors for various flat pack and quad pack devices. We have numerous Contactor designs from our 621 series of Contactors for 3/4" X 1" Flatpack Carriers to our 625 Series of Contactors for 2" X 2" Quad Pack Carriers (and sizes in between). We also carry a wide range of very cost effective carriers including those for “J” lead devices, 
TO’s, Pin Grid carriers to the more standard Quad Packs. If it’s still in production somewhere, we probably have a solution. Call or e-mail WELLS-CTI today for a quote of our multiple sizes and flavors of Carriers, Clips, and Contactors.
Posted by James Forster on Fri, May 06, 2011 @ 09:50 AM
Just after lunchtime on March 11th the people of Japan experienced the horror of what is now called the Tōhoku earthquake and tsunami. Americans woke the next day with the first images on TV with warnings to those in Hawaii and the West Coast as the Tsunami traveled across the Pacific. I, like many who work in or on the periphery of the Semiconductor industry, watched with concern; first for the people I knew in Japan at the WELLS facility in Yokohama, Sato, Kobayashi, Sasaki, Harada, Inagaki and others – and then for their families and friends. As the full extent of the damage became apparent the concern spread to all the people of Japan. Buildings washed away, power outages, transportation stoppages –the list of complications grew by the hour as the full scope of the disaster became apparent.
Photo courtesy of National Geographic (http://news.nationalgeographic.com/news/2011)
We all breathed a sigh of relief when we learned that our team in Yokohama and their families were safe and unharmed. There was minor damage to the WELLS office but nothing serious.
Everyone was stunned by the speed and immensity of the damage – we’d seen it all before a few years ago in 2004 with the Boxing Day Tsunami in Banda Aceh, Indonesia but that did not prepare us or lessen the horror of watching as entire cities were washed away. The beach or seaside is a place of recreation and enjoyment – not the source of this kind of destruction; this was the dark side of the ocean.
The names Sendai, Miyagi Prefecture and Fucushima became familiar as the details of the disaster became apparent as we watched people trying to deal with the aftermath.
Now a few weeks later we realize that we are just one small world – the connections to our lives and economies are being revealed everyday … Honda and Toyota’s announcement of potential shutdowns of their facilities in the USA and Europe. Customers asking for detailed responses outlining our supply chain and potential impacts on delivery. Planet earth is small and we are connected.
Once again we got a series of lessons:
- in the power of information and the way the internet has changed our access to information via blogs, news reports, videos etc
- in global economics and how we are all intertwined in ways we take for granted and perhaps did not fully appreciate or understand.
I was prompted to write something about the disaster in Japan after getting a couple of e-mails with information I wanted to share with others ----
To see the impact of the tsunami these aerial photographs with a slide bar show the before and after give an idea of the damage
http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm
This from EE Times provides some interesting background …
http://www.nxtbook.com/nxtbooks/cmp/eetimes032811_japan/#/1/OnePage
This disaster like the earthquakes in Kobe, Haiti, the tsunami’s in Pakistan and Banda Aceh, will soon fade from the front pages and lead stories on the nightly news but will leave indelible images in our minds of what can happen and how we are all connected.
Words are not enough – as with every disaster the world community rises to help and Americans are typically at the forefront of that assistance. The US government has sent, and continues to send a variety of help. Matt Bergeron, CEO of WELLS-CTI has agreed to match donations up to $1,000 from the employees of WELLS. So, even in these difficult financial times, reach into your pocket and do what you can. There are many agencies you can donate to and every penny will help – as usual we can take a lesson from children who, in many communities have tried to do something…
http://rye.patch.com/articles/rye-school-district-donates-to-japan-relief-efforts
http://www.bayridgeprep.org/page.cfm?p=521
http://www.insidehalton.com/community/burlington/article/978289
When words are not enough try to do your part and contribute.
If you have any comments or thoughts please post a reply or send me a note at james.forster@wellscti.com