> > OK, instead of 30 BAV99 at 5 cents each. =A0What would you suggest?
>
> BAV99W as they are smaller.
Yes, that would help.
> They are less than 2 cents each in large quantities.
May be 1 cent each to mount. We don't have space to mount on top, so they have to be on bottom of the PCB. Assembly is not going to be fun with smd on both sides. I wish they have 8 to 10 in a pack, with common power and ground. Isn't this a very common need?
> John
I think I'll go with this 18 channels TVS diodes for the input.
-2-ND
n .
And for the output buffer, Should I use ALS245, HCT245 or ACT245? I think ALS can withstand ESD the best.
It is, for instance NXP has a large portfolio of ESD protection devices. Many are CSP though (just a bare die with solder balls). Maybe your assy house can process them.
robert
Yes, I need it in the shape of a 26 pins connector. Here is the picture of 0603 version. I will try 0402 as well
Thanks for the many suggestions. In particular, the following ideas:
Larwe: spark gaps Jamie: TVS diodes Johns (Larkin/Devereux): RC clamps
Additionally, I found that HCT claims better ESD immunity than ALS. Both are much better than CMOS micros.
The QFN package has 15 mils gap between signals and ground pad. I will reduce it to 7 mils in PCB.
The unnamed manufacturer (many of you would have guessed) could have done a better job in ESD protection, but the high failure rate indicates otherwise.
I am going to install two diodes back to back between two pins (around
8 mils apart). 0603 is slightly too big. 0402 would be perfect. It would help if I can pre-joint two diodes before mounting on the PCB. What can I use to pre-join them? High temperature soldering? Micro- welding?Have something to add? Share your thoughts — no account required.
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