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May 2010

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Subject:
From:
Paul Edwards <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Paul Edwards <[log in to unmask]>
Date:
Mon, 3 May 2010 11:01:49 -0700
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Colin,

How close is the nearest ground in your PCB?

How is the HV routed to the exposed metal pad that I assume is Au-plated?

Have built RoHS PCAs with FR-4 type PCB material at +3kv operating and found that the leakage path between the HV via and the GND run along the glass reinforcing bundles until they plate a circuit and short out the HV supply, unless the open air load is a lower resistance path...

Rotate the weave, offset the via grids, bake the laminates and seal the PCB... 

Paul

Paul Edwards
Surface Art Engineering

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of colin mcvean
Sent: Monday, May 03, 2010 12:00 AM
To: [log in to unmask]
Subject: [TN] Question for High Voltage guru's

Ladies and Gentlemen of Technet-land,
 
Let's consider an application based on FR4, originally manufactured on ceramic base materials:
 
It generates a plasma field from the surrounding air, neutralizing any airborne particals and nasties!
 
It operates at around 3KV, for a period of time then resets.
 
Given passivation layers of FR4 are varied dependant on laminate suppliers supply-chain at the time of lamination, then what influence will this change have? i.e. Would I expect to see any issues with different copper suppliers and passivation types?
 
note: Qualification testing is under load 20% of the time at 3KV under 85/85 damp heat conditions for 1000 hours. It has been qualified on original FR-4 samples, but now I'm worried about this potential change from my laminate supplier.
 
looking forward as usual to comments and advice
 
Colin


      

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