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My company is singulating a lead frame populated with ESD sensitive ICs and many are failing due to ESD damage. The singulation process requires tape that prevents proper grounding, so a charge builds up on the plastic package. When the parts see grounding after singulation, the charge dissipates and causes the ESD damage.

We've introduced CO2 to make the cutting water more conductive and increased the RH as much as 60%, and used ionizers, but it hasn't been enough.

I'm wondering if it's possible to install a capacitor on the lead frame to prevent or reduce the charge build-up so there is less static charge to dissipate?

Before singulation, all metal, inputs and outputs, are electrically connected, but at the time of singulation, the metal is disconnected.

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    \$\begingroup\$ What is "singulating?" I've never heard that term before. \$\endgroup\$
    – JRE
    Jan 4, 2023 at 17:01
  • \$\begingroup\$ A capacitor isn't going to help you, but you could try installing a grounding electrode in the cutting water supply right before the nozzle. Use a corrosion-resistant material that doesn't build up an oxide layer, like a graphite rod. "Singulation" refers to cutting out individual dies or packaged chips from a larger carrier (wafer, leadframe, etc). \$\endgroup\$ Jan 4, 2023 at 17:04

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It is typical for device in floating scenarios to acquire high voltages and subsequently get destroyed when they are grounded.

It can be even enough to bring them in contact with another floating, but large and well conducting object. The charge redistribution between the tiny IC and large object will still be fast and lead to ESD damage.

The solution is to ground them on a weakly conductive material, like an ESD mat or even an antistatic bag. This will drain the charge slowly - (milli)seconds instead of nanoseconds.

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  • \$\begingroup\$ There are also static-dissipating ionizing blowers that sound like they'd be able to help in this situation. \$\endgroup\$
    – vir
    Jan 4, 2023 at 18:14
  • \$\begingroup\$ @vir OP wrote that that didn't help. \$\endgroup\$
    – tobalt
    Jan 4, 2023 at 18:31

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