Dynamic Burn-In of High Pin Count Logic Devices with Monitoring Capability
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Optimize Your Burn-In Design
By: Randy Spivey, Randy@ceibis.com, VP Sales & Marketing, CEIBIS

Traditional burn-in driver electronics are not meeting the demand of ‘high pin count’ devices burn-in requirements. The increasing pin-count and more complex devices for the ‘high reliability applications such as automotive, medical ICD, and military’ require higher quantity of drive channels with monitoring capability.

Higher device pin count requires that the burn-in equipment contain a larger number of Drivers and Sensors that can be configured as driver channels, sensor channels, or channels with a dual role. The voltage ranges should be near the 0 to 5 volt range.  Memory speeds are also a factor.  With Flash you should be able to access memory at 10 MHz and with SRAM closer to 25 MHz.  Memory is allocated behind each pin so that it can drive and sense signals at higher speeds.  The greater the memory depth, the higher the test coverage you can achieve, so you should have 16 Megs behind each pin.  For certain applications you may want to have greater memory, so you should be able to cascade memory and access it serially, using some standards like Serial Vector Format (SVF) that is used in JTAG testing.

The monitoring channels should be able to record the time and date of failures for better report preparation.  The system should be able to monitor DUT outputs of either vector comparison, sign of life, frequency, or voltage.

To confront the high current and low voltage requirements of burn-in testing, Power Module should support three isolated power regulators with current as high as 30A and voltages as low as 0.5V with 12 bit precision programming.  An optional low cost Bulk Power configuration should also be available.

INCAL‘s ‘Infinity 160 Tracer® Burn-In System’ addresses many of these requirements.  A number of companies in the Medical, Military and Micro-Processor markets and many ‘test houses and laboratories’ have adopted INCAL’s ‘Infinity 160 Tracer® Burn-In System’ platforms.  See more information on this system at http://www.incal.com/isystem.htm

Randy Spivey, Randy@ceibis.com, VP Sales & Marketing, CEIBIS

In order to optimize your burn-in design a number of questions should be answered.  At CEIBIS, we use a one-page technology questionnaire in order to understand the total application in a time efficient manner. Regardless of process node, device technology, or system environment- our goal is to ensure a product with premium signal integrity and accurate power sourcing.

You should have the following information for calculating trace impedance, high speed/signal integrity design verification, and tuning/termination resistor values:

• Device VIH/VIL
• Device max/min VIN
• Device I/O IBIS model
• Clock skew tolerances
• Critical signal edge timing specification
• System frequency

The following information is requested for final test and validation.

• Junction/Ambient temperature 
• Device power supply settings 
• Estimated DUT power 
• Test patterns/vectors 
• Passive or active thermal control

One should expect, if they are dealing with a full-service burn-in board manufacturer that they will use the latest intelligent software and simulation tools to predict the performance of critical signals during the burn-in environment. The days of using a mechanical drawing software are long gone. We routinely design boards with specific rise/fall times for critical clock signals and can actually email o-scope pictures depicting the waveform of the signal including overshoot/undershoot prior to the board ever being fabricated.

Of course, not all designs are that critical and requiring of such pre-design engineering. In those cases, one should still expect that the burn-in board manufacturer that they choose will incorporate “best known” design practices gained by supporting a wide spectrum of technologies and incorporate into their burn-in board strategy at a minimum the following:

• Routing topology that minimizes signal reflection
• Controlled voltage drop across the board
• Thermal budget assessment that incorporates the correct selection of material thickness and design of plane layers to insure both sufficient current carrying capability and DUT (device under test) isolation, if required

Burn-in board designs, regardless of the complexity of the device, requires a thorough understanding of the application to insure that the end-product is robust and creates a platform for a successful qualification and/or production burn-in.  Optimized burn-in board designs begin with an understanding of which questions to ask and having the right tools and the expertise to engineer the right solution.  At CEIBIS, we incorporate the use of our one-page technology questionnaire, pre-design review meeting and close interaction between our design team and the customer all contributing to an optimized burn-in board design.

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