Absolutely. Good practice if the shielding is not so critical.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Wolfe
Sent: Wednesday, January 13, 2016 2:42 PM
To: [log in to unmask]
Subject: Re: [TN] Post HiPot Testing, Power Supply leakage failure, (as related to the setback from PWB edges)
Very good point with respect to HiPot, however in all honesty keeping larger pull back or clearance in general on all layers not just internal planes to mounting holes is generally a good idea anyway.
Many times the hardware like int/ext tooth lock washers are not thought about and can dig into a plane close to surface.
This also leaves possibility to open up hole if required without needed to change layout.
It leaves you with possibilities.
If there is room, regardless of min electrical rules, I always try to leave a wide berth around any mounting holes/hardware as standard practice.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, January 13, 2016 3:05 PM
To: [log in to unmask]
Subject: Re: [TN] Post HiPot Testing, Power Supply leakage failure, (as related to the setback from PWB edges)
This also relates to the recent thread of the subject where several people asked what clearance was required for edge pull-back of the internal copper layers to the edge.
High-pot failures have been known to occur simply because the copper was .020" or less from the edges/holes in the PWB rather than the standard .050"(or more as required by design), thus allowing leakage to occur to chassis, test fixtures, or mounting posts.
Keep that in mind when attempting to determine set-back, the operating voltage of the CCA may not be the only voltage to be concerned with. Common Hi-pot testing is done between 250v to 1000v, even more in some cases. If your design is going to undergo hipot testing, it must be designed to be able to withstand the test voltage. The edge setback issue can be negated by proper fixturing using non-conductive materials, but you need to be aware of the potential for leakage. Plated-through tooling holes near active circuitry are often the path for leakage.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Toby Carrier
Sent: Wednesday, January 13, 2016 1:36 PM
To: [log in to unmask]
Subject: Re: [TN] Post HiPot Testing, Power Supply leakage failure
Victor,
Is the hipot failing when testing line/neutral to chassis ground, or between grounds? How long are you running the test and at what voltage level are you running it? Depending on where you are testing is where it can be one of many items. If you are testing from line/neutral to ground for 1 sec (production testing), and the unit fails, then there can be a lead or trace to close to the chassis, or two leads close to each other violating the clearance distance. If you are running the test for 1 minute (design testing) on a production unit, then you could be triggering the protection devices within the power supply.
There are other scenarios based on the design of the supply and application of the high voltage.
Thanks,
Toby Carrier, CID
On Wed, Jan 13, 2016 at 10:05 AM, Victor Hernandez < [log in to unmask]> wrote:
> Fellow TechNetters:
>
> What type of failure mechanism is associated with a HiPot Test Failure
> on a 750W Switching Power supply? The visual did not turn up any damage
> to components exterior structure. No damage to PWB laminate and solder
> mash surface.
>
> Victor,
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
--
Toby
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
This e-mail and any files transmitted with it are the property of Kimchuk Inc. and is solely for the use of the individual or entity to whom this e-mail is addressed. If you are not one of the named recipients or otherwise have reason to be believe that you have received this message in error, please notify the sender and delete this message immediately from your computer. Any other use, retention, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited.
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
