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Wed, 26 Apr 2017 15:01:27 +0000
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TechNet E-Mail Forum <[log in to unmask]>, Carl Van Wormer <[log in to unmask]>
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The copper is 1.5-oz. on the outer layers, and 1-oz. on inner layers.





Carl B. Van Wormer, P.E., AE7GD

Senior Hardware Engineer

Cipher Engineering LLC

    21195 NW Evergreen Pkwy Ste 209

    Hillsboro, OR  97124-7167

    503-617-7447x303

    [log in to unmask]     http://cipherengineering.com





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo

Sent: Wednesday, April 26, 2017 7:48 AM

To: [log in to unmask]

Subject: Re: [TN] PCB delamination at area with ground-plane cutout



what is the copper thickness?

> I have to wonder why the plane was pulled back.  Looks like a DB9, so 

> I'm thinking, low speed signals, possible RS232.  But it could be some 

> high impedance circuit where capacitive loading is a big problem.  Perhaps not.

>  Perhaps the pullback was done not to limit capacitive effects on the 

> traces on that DB9, just a pullback to prevent coupling, as a plane 

> wasn't required.  Just guessing, so as to not impact circuit performance.

>

> If low capacitance is required, it might be a bit more work than just 

> adding a split plane or thieving, as it couldn't be added under the 

> traces--but it could be brought "near" for the desired effect.  But if 

> it was just a "we don't need a plane here, just remove it" then a 

> split plane should be easy enough to use, with a full or crosshatched pour.

>

> Shawn Upton

> Section Head, Test Engineering

> Sensors Business Unit

> Allegro MicroSystems, LLC

> [log in to unmask]

> 603.626.2429/fax: 603.641.5336

>

>

> -----Original Message-----

> From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl Van Wormer

> Sent: Wednesday, April 26, 2017 9:51 AM

> To: [log in to unmask]

> Subject: [TN] PCB delamination at area with ground-plane cutout

>

> We received pictures from our contract manufacturer, marked to show 

> delamination occurring in 2 areas on our 6-layer boards.  The 

> delamination areas were at the electrically isolated communication 

> interfaces that were made with no copper on the power and ground 

> planes to reduce capacitive coupling.  The response from the PCB manufacturer is:

>

> ​​​​​1)defect reason: we used our stock boards to run the 

> thermal shock test, we see the de-lam is only taking place in the two 

> areas without copper (pic 1.jpg),

>     There is insufficient glue in this area that happened during 

> lamination and that is why the de-lam is happening when the customer 

> is assembling under the high temp, 2)correction action:  if the 

> customer needs us to remake, we suggest to modify the design a little, 

> pls see pic 2.jpg, we will fill the marked area with solid copper .

> Please confirm if a remake is needed, we will arrange right away.

>

> Steve Gregory has posted the pictures at:

> http://stevezeva.homestead.com/Carl1.jpg (board cut open for 

> evaluation at board house)

>

> http://stevezeva.homestead.com/Carl2.jpg (picture showing where they 

> want to add copper)

>

> (and 2 pictures of the delaminated areas) 

> http://stevezeva.homestead.com/Delamination_-_is_it_caused_by_missing_

> ground_plane__1_.jpg 

> http://stevezeva.homestead.com/Delamination_-_is_it_caused_by_missing_

> ground_plane__2_.jpg

>

>

> Question to the group:  Will adding copper on the electrically 

> isolated open areas eliminate this type of delamination?  We could add 

> the copper, but not connect it to the system ground.

>

> Thanks,

> Carl

>

>

>

>

>

>

> Carl B. Van Wormer, P.E., AE7GD

> Senior Hardware Engineer

> Cipher Engineering LLC

>     21195 NW Evergreen Pkwy Ste 209

>     Hillsboro, OR  97124-7167

>     503-617-7447x303

>     [log in to unmask]<mailto:[log in to unmask]>

> http://cipherengineering.com<http://cipherengineering.com/>

>

> This message may contain confidential and/or proprietary information, 

> and is intended for the person/entity to whom it was originally 

> addressed. Any use by others is strictly prohibited.  If I sent this 

> to you by mistake, please be nice and delete it, and then tell me of 

> my mistake so I can send it to the right person.

>

>

>


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