18111 LOW RESISTANCE MEASUREMENTS

• Working knowledge of transistor, diode, capacitor and resistor behaviors
• Understanding of simple schematics, dc instruments, and computer hardware control

• confirm porper operation of the system
• identify faulty assemblies
• use the characterization tools
• setup production test for automatic pribing
• set pass/fail limits
• analyze test results
• troubleshoot to the assembly level

As we approach the end of 2022, the semiconductor industry is in a state of flux. Legacy businesses are tightening their belts and reducing capital spending. At the same time, there are a host of new fabs scheduled to come on line in the next few years. Many of these will be located in the US and Europe, reversing the trends of the last decades that led to the closure of so many fabs.

Chris Miller has written a new book that goes into the reasons for this, as well as some of the long term implications. The book – “Chip War – the fight for the world’s most critical technology” recounts how tiny silicon chips constructed from the smallest electronic components ever manufactured led to the creation of an industry gargantuan in scale. It does so by telling the fascinating stories of the leaders like Charlie Spork, Gordon Moore, Morris Chang. Pick up a copy if you can for night time reading.

We wish to take this opportunity to thank our customers and principals for another successful year, and for wishing everyone a prosperous holiday period and a successful 2023.

With Regards,

Jim Reedholm – CEO

• Sensitivity to Damage – Special instrumentation power-up and power-down sequencing is incorporated in the test code.


• Propensity to Oscillate – While needing to be solved at the test fixture, the analog cables and probe cards provided have proven to be well suited for the addition of ferr-magnetic mats, ferrite beads, and/or discrete components for the reduction of transistor oscillation.


• Possibility of Self-heating – High current instrumentation beyond the standard 550mA is available, providing extensions for both 5A and 50A requirements. Pulsed measurement techniques also help prevent excessive heating.

With system lifespans spanning decades, it can be a challenge to know what calibration accessories were delivered with the tool. So that you can repopulate the tool kit, Reedholm Systems offers a number of calibration accessories that can be used to keep the test systems online and running correctly.

• One per test system!
• Test systems should NOT be operated without the SCM!
• Provide easy, cost-effective methods for making Reedholm instrumentation agree with a company’s standards lab.
• In conjunction with Self-Cal software, it helps ensure that every DC value, forced or measured, in a Reedholm system is directly traced to the standards’ lab DMM.

• Typically gets measured annually, so if you can’t recall the last time it was done, now would be a good time to send it in for standard measuring.

Believe it or not, it looks like in person conferences are happening again! It remains our hope that folks will find there way to Monterey, CA for the upcoming CS Mantech in May 2022.

On the Reedholm side, we’ve got three things to share:

• Proven production parametric test systems for GaAs and silicon requirements, and the power (up to 10kV/50A) needed for WBG devices.


• A complete modernization of the legacy Reedholm Intranet software, updated and improved to be a Windows application. This update became particularly timely with Microsoft’s recent announcement about long term support for IE, which we migrate away from in WIN 2.0.


• A new hardware system that eliminates parasitic cabling while eliminating the footprint of the system.

• DR YIELD, who will be demonstrating their advanced yield management software offerings and


• Suragus, who specialize in non contact measurement systems.

With Regards,

Jim Reedholm – CEO

Upcoming Events:

• SCAL: used with customers standard’s lab calibrated DVM to generate transfer table.

• SelfCal: generates gain and offset table for all RI-40 instruments except CMM.

• CMM Calibration: generates correction table for capacitance measurements.

• Main Diagnostics: performs complete checkout of system including cable to probe card.

• Memory Test (HWPAS): used to troubleshoot communication issues with system.

• Memory Test (HWPAS): used to troubleshoot communication issues with system.

• Pin Order: used to troubleshoot wiring of tester analog cabling.

• Status: gives real-time picture of state of instrumentation.

• Hookup: allows direct control of instruments.

• Prober Checkout: used to debug prober control and communication issues.

• Power Down and Up: used to properly power down, and power up, the test system without causing damage.

With system lifespans spanning decades, it can be a challenge to know what maintenance accessories were delivered with the tool, and which ones are now missing. So that you can repopulate the tool kit, Reedholm Systems offers a number of maintenance accessories that can be used to keep the test systems online and running correctly. All of these accessories are discounted by 10% for orders placed through Aug. 31, 2021. If combined with an active service agreement, the discount increases to 20%, again through August 2021. Not too shabby!

• One per test system!
• Test systems should NOT be operated without the SCM!
• Provide easy, cost-effective methods for making Reedholm instrumentation agree with a company’s standards lab.
• In conjunction with Self-Cal software, it helps ensure that every DC value, forced or measured, in a Reedholm system is directly traced to the standards’ lab DMM.

• One side of the card enables one to run DIAG and verify system performance INCLUSIVE of the analog cable or PAC.
• When plugged in the other way, the card can be used for pkg part testing of golden devices such as the test vehicles used in training classes (3096, 4007, etc.)

• Even the best standard DMM cables cause two problems measuring high resistance:
  • Leakage resistance through the insulation between the leads is seldom >109 Ω, so 10MΩ measurements are often off by 1%, or more.
• Noise and capacitive pickup due to an unshielded high lead causes noisy and widely varying readings.
• The Reedholm test cable addressed the leakage resistance issue through use of Teflon insulated cables. Noise pickup due to the cable was eliminated through use of a shielded lead.

• Being able to run SelfCal with PAM modules requires a new diagnostic loop back card with four 1Gohm resistors.
• This new loop back card replaces the loop back plug that was previously used for running main diagnostics.

• Typically gets measured annually, so if you can’t recall the last time it was done, now would be a good time to send it in for standard measuring.

• While this is not shipped with systems, our team finds it useful to ferret out if the problem is in the system itself or with the prober analog cable.
• The loopback plug allows one to validate the system without the cable installed. In other words, it identifies if the issue is with the analog cable.

• Very simply, this module greatly improves access to the test points and pots that you might need to turn in order to calibrate a module.

Here in the US, things are starting to open up after the last 18 months of no face to face visits, except for those online over Zoom.

We expect to be on the road quite a bit in the second half of 2021. During road trips, we strive to include visits to existing and future customers. It was one such visit that helped inspire the content for this newsletter.

Reedholm systems have operational lifespan’s that can span decades. That means the technical staff that first brought in the tool can be enjoying retirement whereas the test system has to keep plugging away in production. And with that retirement, direct knowledge about how to maintain the systems and what maintenance accessories are available can be forgotten, or even misplaced or lost. If that happened at your company, you might be interested in the sale we are having on those accessories in the summer of 2021.

Also, we welcome the chance to demonstrate and discuss RDS WIN 2.0, our latest software offering for our legacy parametric test systems. This update became particularly timely with Microsoft’s recent announcement about long term support for IE, which we migrate away from in WIN 2.0. Details can be found in the datasheet, or in an online review.

Please contact us at [email protected] if you would like to discuss your system updates. We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

• We will be offering a series of one hour classes. These are a mix-match of slides, show and tell, and questions and answers.

• The hope is that the one hour sessions are a big hit, and that we can offer future classes covering other aspects of parametric test (calibration, test plan editing/creation, high voltage measurements, etc.).

• The format will be via a Zoom Webinar. That means you can participate from wherever you happen to be (home, work) but not driving.

1. How to take the system to Minimum Configuration
   
2. How to set address settings for individual modules
   
3. How to set up the instruments and slot dependencies
   
4. How to run Diagnostics
   
5. How to copy and send in DIAG results
   

• Wednesday, Nov. 11 at 11am Central Time (USA)

• Wednesday, Nov. 18 at 9pm Central Time (USA)

• For early registration, service contract customers can use support hours, or pay $200. Or $300 for customers without service contracts. These prices are good through October 31st.

• Prices after October 31st are $400 for service contract customers, and $600 for customers without service contracts.

Please let us know if you would like a quote for any of the items, as that will also allow us to confirm if the items of interest are still available.

As always, customers with an active service agreement are eligible for an additional 10% discount.

Click here for further details

Reedholm systems are used all over the world for the gamut of parametric tests – ranging from process control monitoring, reliability, device characterization, and functional testing. While the systems are quite reliable, inevitably there is the occasional failure. Being able to isolate what is at fault is not trivial, but there are some tricks of the trade that can be employed to simplify this troubleshooting.

You may have been advised before to “take the system to minimum configuration” to aid in troubleshooting. As this might be delving into the unknown for some, we are offering abbreviated on-line webinar’s to teach the basics of maintenance for the Reedholm systems. We hope you find this foray to be worthwhile!

Along that topic, I am reminded of a column I first came across some 20 years ago, with the main lesson of “making the problem worse” as the art of troubleshooting. A short clip of this article can be found below, as well as a link to the full article which we posted on the web site. Thank you Dr. Johnson for this insightful work.

Here is the excerpt of the article: Last week, at a class in Rochester, NY, one of my students asked, “What is the most difficult kind of problem to debug?”

My answer came quickly: “Something that fails every two weeks.” If a device fails less often, you can pretend it isn’t happening and ship the product anyway. If it fails more often, you stand a much better chance of tracking down the source. Every two weeks is about the worst it can be.

Please contact us at [email protected] if you would like to discuss your system updates. We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

Without hot switching, dry reed relays in Reedholm systems have lifetimes of 10^9 operations, with end of life defined by contact resistance increasing to several times the initial resistance of 100mΩ. Even if operated continuously, which never happens, a relay would last more than 20 years. That is why we say relays do not wear out. That is also why we say that relay failures are due to hot switching.

One step in the quest to eradicate hot switching involved changing the power control logic (PCL) board to prevent turn-on of the 120V supplies when AC power is applied by requiring software initialization first. Another source of uncontrolled hot switching are sneak paths that charge unassigned pins, only to have those paths discharged to ground between tests. More details can be found in SN-136 on our web site.

Getting rid of possible sneak paths can be a needle in the haystack problem when a system has been doing production testing for any length of time. Stuck relays and scrambling are highly intermittent events that can bring testing to a halt, even though problem tests vary from wafer to wafer or week to week.

If you have not found the time or resources to change test conditions, but are faced with stuck node 0 relays, you might want to consider changing to matrix modules that have circuitry and software that lowers the chance of a node zero force relay being closed with voltage on a pin. Migrating to the new PAM-16N and CPM-N does not eliminate scrambling or all hot switching, but does minimize damage to node 0 switches, which are the most likely to face hot switching.

Customers that have migrated to the improved matrix card report significantly lower failure rates (19 to 2) and some have seen no stuck pins. One reason is that resistance added to the node 0 sense path prevents welding of the sense relay and provides a discharge path if there is voltage. The force relay is not allowed to close until voltage is less than 1V, which is below the arcing voltage. Thus, even if there is switch bounce, the voltage is too low to transfer material, which leads to welding, or sticking, of contacts.

Please contact us at [email protected] if you would like to discuss your system updates. We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

Thank you again for the positive feedback and many discussions and meeting at the recent CS Mantech (Compound Semiconductor Mfg Conference) in Minneapolis MN, a mere 1,144 miles straight up I-35 from Georgetown/Austin, TX. It is rather amazing how so much of the conference pertains to WBG devices and manufacturing challenges both for GaN and SIC based devices.

We were also happy to host at our booth Suragus, a German based manufacturer of a non-contact systems that utilitze Eddy current meausurement techniques. A number of companies have already been in touch with us about getting samples measured so that comparioson can be made in their aging tools for possible replacement.

The lead article for this month details how and why compound semiconductor manufacturers find Reedholm systems to be a good match for production test requirements. We will be meeting many of you on the upcoming trip to Taiwan/China, so please let us know if there is interest in further discussions at this time.

Again, we thank you everyone for your support and business. We have a lot of interesting things being worked on and in the pipeline, details of which we hope to make available in the not too distant future.

We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

• Replace probe card with loopback card & run main diagnostics

• Run SelfCal

Even the most reliable test systems can occasionally have problems. That’s why this months newsletter focuses on helping customers maintain their investment.

We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

Service Agreements:

Here are four reasons why a Reedholm service agreement simply makes sense:

1. The average price of a non contract repair ($3,450) is 230% higher than the rate of the same repair done under contract (average of $1,500). And the service contract repair is expedited, so it is processed twice as fast.
   
   
2. Customers with a service contract also receive a 10% discount on the purchase of modules.
   
   
3. Customers with a service contract enjoy as much as a 40% discount for applications support. The service contract rate for our hourly rates for apps help ($150/hour) and development ($200/hour) while non contract customers are billed at a $250 rate (apps or development).
   
   
4. A contract allows customers to work from a budget and not have to chase a PO anytime a repair or help is needed.
   

The Probe Card Interface Assembly (PCIA) can interface with any wafer size. The PCIA is robust and trouble free, it is quite reliable. It fits into the same opening as the 9.5″ RC-2 carrier ring used by most prober manufacturers for rectangular probe cards.

Click here for further details

Test Structure and Software for Measuring Thin Film TCR

This product offering consists of test software, a GDSII compatible test structure, testing of at least one wafer, and one day of training at Reedholm. It can be ordered with a new Reedholm test system or retro-fitted in a Reedholm system which has at least three VFIF’s and a DMM-16.

Use of Low TCR Films

Performance of many precision integrated circuits is dependent on low temperature coefficient of resistance (TCR) resistors. For example, analog to digital and digital to analog converters typically use low TCR films in ladder networks and as feedback resistors. Some signal processing IC’s make use of low TCR films for gain setting. TCR values, matching, and stability are extremely important in such applications.

Click here for further details

Our progress continues. It has been a busy last couple of months with systems being shipped all over the world.

On the business front, we are busy at work completing this year’s CARTA corporate valuation paperwork. Everyone that you work with at Reedholm Systems is a shareholder in our entity, which means they have a stake in your success too!

This month we are promoting a couple of test accessories that we hope are of interest:

• Reedholm’s PCIA has proven to be a workhorse for customers, dramatically reducing if not eliminating cable failures that otherwise result in a down test system. And these are matched by simple high-performance probe cards that are wafer size independent. The PCIA is normally shipped with Reedholm test systems but can be shipped for use with just about any test system while delivering sub-pA performance if desired. The probe card end remains the same, however a cable and connector that that matches up to other brands of testers needs to be incorporated.
• The other test accessory is the automated TCR capability. Comprised of a test structure and automated and integrated test routines, this allows customers to gather comprehensive TC data in production.

Finally, we are updating our website with the availability of spares or replacement modules, both new and refurbished. If not immediately available, online ordering will be in place by the end of the year.

We look forward to hearing from you.

With Regards,

Jim Reedholm – CEO

WBG Collaboration with Texas State University & Piner Research Group

July 17, 2018 Georgetown, TX – Reedholm Systems announces, effective immediately, that the Company has formally engaged with The Piner Research Group (located on the Texas State University Campus) to develop reliability methods and standards for production test of WBG devices (wide band gap) as well as to provide technical consulting services to Reedholm Systems.

Both parties recognize the unique needs and challenges faced by WBG device manufacturers and Reedholm Systems’ need to refine its measurement instrumentation and long-term reliability stress capabilities specifically for the GaN, SiC, GaN on Si, and other WBG devices and materials.
Click here for further details

Thanks to all of those that came to see us at CS Mantech in Austin, TX. As always, the organizers at CS Mantech know how to throw a party, with no shortage of food, drinks and snacks throughout the event! Well done!

From discussions about fast production test systems, to ways of dealing with oscillations with high speed devices to novel WBG reliability stress test systems – we were busy throughout the event.

Joining us in our booth at CS Mantech was Dieter Ratheir of DR YIELD. As many of you saw, DR YIELD creates software based yield solutions for the integration and visualization of data and helps you make sense of it. This allows smarter and faster decisions, ultimately resulting in significant cost savings. Once installed, it will quietly sit back and look for anomalies in the data that don’t trigger existing rules and automatically alert your engineers. Let us know if you would like more information.

We will be traveling throughout the Pacific Rim in September. We look forward to face to face meetings with both existing and future customers. If you would like to meet then, please drop us a line.

With Regards,

Jim Reedholm – CEO

Upcoming Events:

The 6th Annual IEEE Workshop on Wide Bandgap Power Devices & Applications
Georgia Tech Hotel and Conference Center

Atlanta, Georgia | www.wipda.org
Oct 31 – Nov 2, 2018

To address the need for statistically significant sample sizes for reliability testing, the WBG systems offer 30 DUT per experiment stress condition and up to 3 simultaneous experiments for a total of up to 90 DUT under stress. Each experiment operates independently of the others and switch in the parametric measurement instrumentation for periodic measurement cycles. Click here for further details

Our focus at Reedholm is on the accurate and fast measurement of test structures, both at the wafer and packaged levels. This focus also makes our systems suitable for final DC test of funtionality for some products.

We concentrate on applications, not the sale of products. We want to ensure the integrated system can be used on the day of installation. This approach can take more time and effort but it is worth it.

We provide data-driven test environments that are easy to use and which eliminate the need to program, making the difficult tasks of interpreting and resolving cryptic run-time and compiler error messages a thing of the past.

Reliability and Durability are designed into each of our systems. Working lives of decades are realistic. State of the art performance is maintained with periodic system upgrades that provide new life at a fraction of the price of a new system.

Please let us know if you would like more information. We welcome the chance to serve you and help address your test requirements.

Sincerely,

Jim Reedholm – CEO
Upcoming Events:

CS Mantech – Booth 713
Hyatt Regency
208 Barton Springs Road, Austin, TX USA
May 7-10, 2018