Reedholm addressed hot switching damage to node zero relays with new matrix designs, by minimizing damage to node 0 switches which bear the brunt of hot switching from sneak paths. The node 0 triple pole, single throw relays (force, sense, and guard contacts) have been replaced with independent single pole relays for the force and sense lines. Resistance added to the node 0 sense path prevents welding of the sense relay, and provides a dis-charge path if there is voltage present. The force relay is not allowed to close until voltage is <1VI, 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.
Getting rid of possible sneak paths can be a difficult problem when a system has been doing production testing for any length of time. Hundreds, if not thousands, of test lists can be affected. Stuck relays and scrambling are often hightly intermittent, and can bring testing to a halt with different symptoms from wafer to wafer and week to week.
Stuck Node 0 (ground) relays problems result in lots of problems for customers. It halts testing, forces reprobing of wafers, and generally cuts down on production test time. Few customers have the resources to do what really ought to be done – fix test conditions or test structures to eliminate the root cause. Part of this is because for many of the products, wafer lots are run years apart.
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@example.com if you would like to discuss your system updates. We look forward to hearing from you.
Reedholm dc test systems are used by a large number of GaAs and other compound semiconductor foundries in a variety of roles. These systems are used by both manufacturing and engineering departments. They offer a high degree of automation in the area of data acquisitionm as well as providing network access allowing engineers to work more efficiently.
We are pleased to open our on-line store, detailing what inventory of factory refurbished and new modules we have on-hand. Refurbished modules are warranted for 90 days, and new ones are warranted for a fully year. In general, boards placed into inventory can be made ready for shipment within a day or two. Please contact firstname.lastname@example.org or email@example.com to get orders placed.
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.
Along with golden devices to confirm proper system operation, we recommend these practices:
a) Run Diagnostics Daily
The best maintenance practices involve these daily maintenance utilities:
Replace probe card with loopback card & run main diagnostics
It typically takes between 5 and 10 minutes per machine, and is well worth the time, as doing so significantly reduces the probability of bad data due to some unanticipated fault. The key is to establish known good system performance.
b) Keeping Software Updated
The newer software does not overwrite old diagnostic reports so previous diagnostic test data can be referred to if an issue appears. The newer software also incorporates many updates to make the system more robust by preventing false failures and flagging marginal failures that may otherwise not be flagged. The tests do not take that long to run and having the data makes it easier to troubleshoot in the event something changes and a problem occurs. Having records permits rapid analysis of shifts.
c) Problem Isolation
When problems occur, the system self-test software determines if there is a fault in the system and what might be causing it. Maintenance personnel ought to be familiar with running all diagnostic utilities, digital module tests and module calibration. Process test results should not be the criteria for determining if there is a hardware fault. If swapping a module is necessary to isolate a fault, good practice dictates recording of module serial numbers and pre/post test results. In numerous cases where multiple modules were swapped, the wrong module has been sent in for repair.
d) Log Book Maintenance
Log books also should be maintained so that the information about a specific module can be recorded. As modules are interchangeable, data that shows VFIF-16 #3 was swapped is not much help. The serial number is needed.
The loopback plug is a handy tool to use if the PAC or loopback card is suspected of causing diagnostic tests to fail. The TAC plug allows the system performance to be confirmed without a PAC installed. The loopback plug is for CPM based systems only.
The plug is priced at $4,300 and make sure to specify whether you have a CPM or PAM matrix.
P/N 11094 Shielded Extender Module
The shielded extender module is used for all Reedholm systems. Card guides are put on the sheet metal so that both vertically and horizontally installed modules will be properly supported. For example, the same performance is provided in a bench-top RI-40 modular chassis as in a seven-foot RI-51 TDDB system.
Reedholm’s SelfCal module (SCM) provides a simply way to link accuracy of dc instrumentation in a Reedholm system to that of an external digital multimeter. If the accuracy of the digital multimeter (DMM) used to calibrate the SCM can be linked to a certified calibration laboratory, the accuracy of the Reedholm test system can thus be certified.
The Loopback Card is a maintenance fixture that can be used to check system performance with a PAC or TAC/PAC installed.
The price for the Loopback Card is $4,300.
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.
Jim Reedholm – CEO
Here are four reasons why a Reedholm service agreement simply makes sense:
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.
Customers with a service contract also receive a 10% discount on the purchase of modules.
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).
A contract allows customers to work from a budget and not have to chase a PO anytime a repair or help is needed.
Maintenance Training Class:
We also believe having a one to three day training class would help on the maintenance of your Reedholm system. We would be teaching the basics of how to confirm the system is working correctly, how to calibrate, and how to fault find to a problem module.
The cost of the class would be $5,000 to $7,500 inclusive of expenses, contingent on our ability to get a few other local accounts to sign up for a one day class. Of course, flexibility when scheduling from all sides is paramount. We will also need to have the test system available for the labs.
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.
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.
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.
Tough Testing Challenge: Fast Low Current Measurements of Photo Diode Arrays GaAs fabs produce photodiode array optical device wafers with, sometimes, hundreds of thousands of diodes resulting in lots of pixels which have to be electronically tested, typically in the pA range causing a production and engineering challenge.Rack and Stack systems used for testing often prove to be a production bottleneck. Significant faster and higher throughputs are possible with standard Reedholm Test Systems, for example a 4x speed gain was achieved using Reedholm Low Current Measurements with the PAM-16>1pA resulting in a 1.8 hour test cycle for 100,000 pixels improving from 12 hours. Click here for further details
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.
Jim Reedholm – CEO
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
Tough Testing Challenge: BVCEO Breakdown Measurements – AN-124 Measuring BVCEO is tricky at any voltage and is a slow test at low IC because any charge injected into the base when biasing the transistor has to fully recombine before an accureate measurement can be made. Several Reedholm routines used to directly find BVCEO are characterized in terms of speed and resolution, illustrating the speed issue. In addition, a couple of methods are described that produce results much faster than the direct method of measuring BVCEO at a specific IC. Click here for the full applications note WBG Reliability Test: HTRB, HTGB, HTOL
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.
Jim Reedholm – CEO Upcoming Events:
CS Mantech – Booth 713
208 Barton Springs Road, Austin, TX USA
May 7-10, 2018
Tough Testing Challenge: Measuring RDSon and VCEsat in Biased Chuck Systems – AN125
High power devices built on silicon carbide and other types of substrates achieve maximum performance through use of vertical structures with the drain or collector at the bottom of the stack. Screening high power transistors also requires measurement of low level on resistance and saturation voltage. Click here for the full applications note Cost Effective Service Agreements
Most customers enjoy significant savings by having service agreements in place. Besides a lower net price on repairs, customers with contracts receive discount pricing on the order of other goods and services. Agreements can be structured in a number of ways, either just for repairs, or for a combination of support hours plus timely repairs. Contracts run a full year, the price of a single system annual agreement is $6,000, coverage for two systems is $8,000, three systems $10,000 and four or more are priced at $12,000. We recommend some combination of repairs and hours so that help can be provided without delay to help trouble-shoot during down situations. Coverage starts once payment is received. Please email firstname.lastname@example.org if you wish to consider an agreement. Please let me know if this has your support and we can prepare a contract/quote. Click here for further details
MEMS Fab Complex in Scotland
Client Profile: Semefab – UK
Semefab (www.semefab.com) is a silicon wafer foundry operation manufacturing microelectonics and MEMS in Glenrothes, Scotland. It accomplishes this with three fabs. This enables Semefab to work with customers, large and small. Clients can choose to utilize standard process building blocks, or implement customer processing steps as required. Click here for Profile
On behalf of the entire Reedholm Systems team, we want to thank everyone that has helped make our first full year of operation a sucecess and a profitable one to boot.
We provide comprehensive support to the installed Reedholm base, covering repairs, module and assembly sales, technical support, as well as the successfull sales and installations of systems. We’ve also signed a comprehensive agreement with STAr for sales and support activities throughout the Pacific Rim.
We have a number of improvements in the works. As detailed on our web site, our instrumentation modernization design effort is underway, starting with a surface mount version of the DMM-16 module. We also have software modernization activities to discuss, including a migration to a Linux version.
We are also leveraging our experience in Wide Band Gap device testing to the reliability realm and building a constant current packaged reliablity test system specifically for GaN HEMT devices.
If you are interested in any of the above, or have different test interests, please reach out to us. We are here to help.
Here’s wishing everyone a prosperous 2018,
Jim Reedholm Upcoming Events:
IRPS – Burlingame – San Francisco, CA USA
March 11-15, 2018
Tough Testing Challenge: JFET Gate Current Measurements – AN 111
A customer with a picoammeter matrix (PAM) card and a low leakage probe card, both from Reedholm, had a new requirement to measure gate current of junction field effect transistors (JFET’s), but was unsure that it could be done rapidly enough for in-line testing. The evaluation performed by Reedholm showed that sub-pA gate leakage testing could be done in <1 second per die, and faster if there was no leakage introduced by device packaging or the probe card. At 200msec test times, uncertainties could be <±100fA. These conclusions were based on gate leakage current measurements of four JFET’s bonded in TO-5 type cans. They were tested at Reedholm on a PAM-12 based RI-40 with a PCIA interface and a low leakage DUT card. The quality of the test fixturing was more than adequate for measuring the true current leakage of the JFET’s. Data was also generated for an open socket condition and for a Motorola 2N5486 JFET. Click here for the full applications note 100kHz Reedholm Capacitance Meter On SaleThrough the end of the year, the Reedholm 100kHz capacitance meter is available at a 25% discount. Consider taking this opportunity to either add this capability to your parametric test system, retire your unsupported third party HP/Agilent or Boonton capacitance meters, or as a spare to help ensure tester up-time.
A major performance advantage is the virtual elimination of inductance effects due to signal path lengths. Self-inductance requires up to 10% adjustments for apparent capacitance errors at 1MHz are reduced by 100:1 at 100kHz. Another advantage is that there is very little ac noise near the 100kHz frequency compared to 1MHz. Click here to go to the web site for more details.
BCD HQ in Shanghai
Client Profile: BCD/Diodes Inc
Asia is the largest market for semiconductor consumption. There are very few analog providers and even fewer power management IC vendors in the region. OEM’s and ODM’s frequently look to BCD to provide system-level insight as well as design and technical support to reduce time-to-market. Click here for Profile
The sun never sets on Reedholm Systems. That’s because Reedholm products are found worldwide in large and small semiconductor companies, handling everything from routine process control to production die sort, to a variety of wafer and packaged level test requirements.
We have a rich 30+ library of IP to draw from and a new management team. Simply put, we want to make it possible for customers to have test system that work the way they need them to. We have a host of projects under consideration, ranging from SW extensions to HW improvements designed to modernize and continuously improve our systems.
Whether this is your first time hearing of us, or you are an established customer, we hope you find out newsletter to be technically informative. We welcome the chance to serve you and help address your test requirements.
We look forward to hearing from you.
Jim Reedholm Upcoming Events:
WiPDA – Albuquerque New Mexico, USA – October 31 – Nov 1, 2017 : Wide Band Gap Semiconductor Workshop