Tekmos' Blog

Over the summer we rolled out an Enterprise Resource Planning (ERP) system. The aim of this system is to automate many of the day to day tasks we deal with at a company level and reduce the chance of miscommunication between employees.

The system we use is broken down into “Projects” and “Issues”. A Project is what the bigger picture would be, for example, travelers, new engineering test releases, sales orders, etc. An Issue is a single instance of the project, such as a single traveler for a specific part, a new test for a part, or a sales order. Although our ERP system is still a work in progress, we have currently moved our traveler system for testing parts to a digital system and as a result have improved productivity by streamlining the process.

To accomplish the traveler system, multiple databases have been created that contain our commonly used setups for hardware, software, and testing. This information is then automatically populated into the travelers. This allows the test engineers to speed up the initial stages by having all the information they need available to them instead of having to ask the engineers for the appropriate setup information. We have also integrated several tablets into the system to allow for the digital traveler to travel (move) with the parts from station to station, in a way similar to how the paper travelers moved with the parts.

The databases from the travelers play into the engineering test releases as well. Prior to this system there was never a clear database that was updated with all the approved hardware configurations. When the engineers completed tests, these tests were released to their standards without a universal internal standard. To help with the population of the database another project was created to keep track of these tests.

The sales order Project prompts whomever is processing the customer order for the basic information about the order and then sends this information to the next person to work on the order. After the information is entered into the system, an automatic email is generated and sent to the customer informing them that their inquiry has been received and an update with specifics about their order being processed will be sent soon. With this system all of our sales orders are presented in one place with the date they were received and entered, as well as reminders being sent to key people to follow up on the progress of these orders if they aren’t handled in a timely manner.

As a fabless semiconductor company, Tekmos outsources wafer fabrication and device assembly. The decision to outsource testing is more complicated. As a basic philosophy, Tekmos would prefer to do all testing in-house. This is driven by a need to control a major component of the manufacturing and to insure that our customer’s priorities are being met. But we occasionally get either product types or package types which we cannot do in-house, and so we outsource the testing of those parts. The deciding factors are a combination of pin-count and package type.

Our largest tester has 320 data channels and can support parts up to about 400 pins. If the pin count is higher than that, we will have to either design a custom tester, or outsource testing.

The package type and its associated volume is another factor in deciding to outsource. Any part can be manually tested, but manual testing is slow, and so we only use it for low volume parts. Higher volume parts have a lower cost, and are more sensitive to the test cost. Tekmos has a number of handlers, and tape and reel machines, but we don’t have the capability for tray-fed tape and reel. Or at least we didn’t until last month.

In the last year, we have seen a large increase in our consumer products volume. And since most consumer ICs are QFN devices that are sold in a Tape & Reel format, we have needed to increase our T&R capacity. Our current machines are tube fed, but we needed to get one that was tray fed to handle the QFN packages. So, we purchased a second Tape and Reel machine.

Our new machine has a capacity of about 2000 units per hour, which translates to about 15K units per day with a single shift of operation. It also has an optical inspection capability, that checks to make sure that the package is orientated correctly in the tape before it is sealed.

The National Institute for Standards and Technology recently released a set of standards for cyber security. Defense contractors are required to implement these standards by the end of 2017, and that applies to Tekmos. We started off already being compliant with about half of the standards. Achieving compliance with the other half of the standards is more of a challenge.

One major area we are working on is formal documentation. The NIST standards require formal procedures for all aspects of cybersecurity. We already have informal procedures, but converting all of them to formal procedures is a major undertaking. The one advantage to creating all of this documentation is that it fits in with our AS9100 documentation we are creating for our certification audit later on this year.

The second area of work is the addition of card readers to each PC to only allow authorized users on each work station. At first, this seems straightforward, but becomes more complicated when our testers are taken into account. The testers are tightly coupled to engineering, and so are part of our network. But they also run independently, and we have one operator taking care of multiple tester / handler configurations. It is not clear how we will address this.

Another interesting area is the requirement of a whitelist for approved programs. Engineering will frequently try out new programs as part of their jobs. And so the procedures need to be written to allow this, while still providing security.

There is still a lot to do, but we are optimistic that we will be compliant by the deadline. And give the increased cyber threats these days, it is good to be improving our defenses.

Tekmos offers Burn-In and Reliability Testing services.  The requirements can vary from part to part, and Tekmos can customize these services to meet your exact needs.

Burn-in

The failure rate of integrated circuits over time follows what is called the "bathtub" curve.  There is a high rate of infant mortality initial failures.  Then the failure rate drops, only to increase at the end of life due to wear out failures.  The reliability of a part can be enhanced by providing a burn-in at elevated temperatures prior to usage.  This burn-in is typically somewhere from 40 to 160 hours in length, and is done at a temperature of between 70ºC and 125ºC.  It is important that the parts be exercised during this burn-in.  It is also good to monitor the part performance during burning, so that the time point of failures can be detected.  That data can be used to set the optimum burn-in length.

One of the major costs of a burn-in is the boards used for the burn-in.  This is a tradeoff between the cost of the sockets on the boards, the number of boards needed, and the total number of parts to be burned in.  Major manufacturers with very high volumes will invest in high quality sockets that will cost from $50 to $100 per chip.  This socket cost adds up quickly.

In addition to the oven capacity, Tekmos also has in-house design and layout capability for both the burn-in boards and driver boards (if needed).

Reliability Testing 

There are several over-lapping reliability testing specifications.  Specifically, these are the JESD47I, the AEC-Q100, and the military Mil Spec 883.  These require subjecting several lots to stresses, and then looking for failures.  Some tests are for the die, and other tests check the packages.  Because of the standardization of the packages, the die tests are the most important.  And the main die test is the HTOL, or High Temperature Operating Life.  In this test, the parts are typically operated at 125ºC for 1000 hours.  If the parts cannot be tested in the oven, the parts will be periodically pulled from the oven, tested, and re-inserted back into the oven.  Common read points are at 48, 96, 168, 250, 500, and 1000 hours. 

Tekmos offers test and characterization services. As a fabless semiconductor company, Tekmos has an internal test facility, with testers ranging up to 320 pins in size. We offer access to these facilities and the engineers that run them.

Verification and Debug of ASICs 

Some customers have developed an ASIC, but lack the facilities to completely test it, or to debug it if there is a problem.  Our testers provide the means to verify the ASIC, and to debug it.  Also, our testers can be remotely accessed, allowing the customer engineer to exercise their part from the comfort of their own office. 

Verification of Brokered Parts 

Brokers have become very efficient in obtaining mature parts.  But there is always the question of if the parts are correctly marked,  and will they perform to specification.  Re-testing the parts is the best way to resolve those questions.

Test Program Creation 

Customers do not always have a test program for their parts.  In those cases, we can create one from scratch.  Starting from either design files or a data sheet, our engineers can write patterns that functionally exercise the parts.   

Product Characterization 

The question for all new parts is does the part meet all specifications over the temperature and voltage limits?  And the only way to find out is to measure it.  Tekmos can take your part, and measure the functionality, DC specifications, and AC specifications over the desired temperature range.  Then we consolidate the data into a report, that shows how well the new part works as compared to the specifications.  This service is useful for both new designs and to evaluate existing designs.