Regarding L6585D/DE Based Design

vilas · ‎2010-05-28

Posted on May 29, 2010 at 08:37

One of Our Client Facing following Problem :

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1.

IN PRODUCTION & TESTING Ballast PCB Board(24W, PRODUCT) USING L6585D/L6585DE WORKS FINE.

2.

BUT, IF CUSTOMER KEEP THIS PCB Board IN STORE FOR 1-2 WEEKS. And after Couple of weeks if he tried to use these boards for Assembly, CUSTOMER FACING FOLLOWING PROBLEMS :

A.

SOME BALLAST PCB SWITCHES ON AND OFF AFTER 3-4 SECONDS.

B.

SOME BALLAST PCB DOESN�T WORKING.

C.

SOME L6585D/DE SHOW PIN NO. 17(VCC) & 18(OUT) SHORTED.

D.

SOME L6585D/DE SHOW PIN NO.15(GND) & 17(VCC) SHORTED.

E.

REJECTION IS AROUND 25-30%.

F.

Problem is not same for all L6585D/DE, it varies Ballast to Ballast.

G.

If he done production and assembly at the same time, problem arises in couple of weeks in the same manner.

3.

BUT, IN ANY CASE IF WE REPLACE L6585D/L6585DE BY NEW ONE BALLAST WORKS FINE.(AND AFTER THAT IF WE KEEP IT IN STORE, CYCLE/PROBLEM REPEATS AFTER FEW DAYS.)

Accoring to client, this is Problem arises due to static effect.

Kindy Guide if You have Solution.

#l6585d/de-based-design

Vipin BOTHRA · ‎2010-06-28

Posted on June 28, 2010 at 23:56

Hi Villas,

What is the humidity level where the unit is stored for 2-3 weeks? If it is happening this time of the year and in warm weather it very unlikely to be static electricity caused issue. Can you do a coating (Conformal coating) on about 10 units and see if they exhibit same problems?

-

Vipin

vilas · ‎2010-07-01

Posted on July 01, 2010 at 09:28

Thanks for Support/reply.

Can you please tell me what is Conformal coating? & how to do it?

& How to measure humidity?

(Kindly advice, i am new in Semiconductor field.)

Vipin BOTHRA · ‎2010-07-28

Posted on July 28, 2010 at 16:41

Since you do not have humidity measurement capability, I suggest you take units where you expect to have large number of failure. Bake them in an oven (just like you would bake a cake) at 120 degreeC for 1 hour and retest them after cooling them. If you notice that failure rate decreases significantly, you can conclude that issue was related to humidity.

Vipin