Testboar requirements for highly accelerated stress testing.

[b.o.o.m]

Hi,
we are currently setting up our qualification process for a new chip and need a test board for highly accelerated stress testing (JESD22-A110-B). Since i don't have any experience with PCB design for this kind of environmental conditions i'm looking for some information about material requirements for such a test board.
The board will be used in a hast chamber and probably driven at a temperature of around 125C with 85% humidity.

What i already got about the PCB requirements is that i need another base material like G200 with chemical gold finish. The traces would be placed on a inner layer for protection of the humidity environment. What are the requirements for the soldering? Is a standard lead soldering process adequate for such applications?
Furthermore i need some capacitors and sockets, but i think there are plenty of products that tolerate such environmental conditions.
Is there anyone who has some experience with such applications?

Thanks in advance.

 

[ASIC]

I assume that you will add some components to that PCB, and generally semiconductors can not operate at that temperature.

 

[b.o.o.m]

Re: Testboar requirements for highly accelerated stress test

Thanks for the hint. I checked back with some designers about our chip and it shoudln't be a problem. But ill get some simulations to get shure of it .

For the rest of the components i have only some capacitors and connectors on the board, since the chip does only need power supply and clocking for the testing and no full function circuitry.
I thought about some X8R capacitors, since the are specified with a maximum capacitance change of +-15% up to 150C.

 

[rikie_rizza]

I think what you're about to build is a burn in board... is that true?

 

[b.o.o.m]

Re: Testboar requirements for highly accelerated stress test

Yes, most probably for an espec EHS-211 or EHS-411 HAST chamber.

 

[rikie_rizza]

Use solid capacitor...you will cook your capacitor if its not solid.

Usually, no semiconductor on BIB (burn-in board), all are passive components. Your PCB material can meet the requirement I guess.

 

[b.o.o.m]

Re: Testboar requirements for highly accelerated stress test

X8R are high temperature capacitors that work up to 150C :wink:.

There will be no active components for circuitry, except for the chip that has to be tested , i only need some stabilizing capacitors.

But again, what about the soldering? Are there any special requirements to that? (since the solder joints are exposed to these conditions for a long time).

 

[rikie_rizza]

As far as I concern, there is no specific exclusivity on solder material. Actually solder melts at 210C and become very 'wet' at 240C. At 150, solder will not be a problem.

 

[b.o.o.m]

Re: Testboar requirements for highly accelerated stress test

I'm concerned more about the humidity (85%) since a vapor pressure of 33.3psi (2.3bar) is needed to reach this value at 130C :|. Its a test for accelerated lifetime simulation, so all the solder joints are stressed too.

When googling around i found several manufacturers of such H.A.S.T boards that promote "high temperature" soldering or use of solder without silver. Furthermore they wash the boards to get rid of the soldering flux. It just seems like corrosion could be a problem (or its only some marketing thing that has no influence if not testing for 5000hrs).

I think ill invite some offers for an all-in-one solutions.

 

[rikie_rizza]

Washing the board to wipe away flux it does not mean they use water...its more like dry cleaning, the use chemical instead of water and solution.

 

[Samina Lee]

Re: Testboar requirements for highly accelerated stress test

It's appreciated that you could get so many positive suggestions. Have you settled the problem?

 

[b.o.o.m]

Re: Testboar requirements for highly accelerated stress test

Were currently in contact with a company that can provide us such a board. The impression I got so far is that its not that kind of a big deal for our application. Most part of it is about choosing parts and cables that can resist these conditions. For soldering a standard process is used. Since we've not ordered yet I don't have detailed information about the board itself.