ORCAD Query

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#1
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Hi Everyone,

I use Orcad Layout Plus for my PCB design. I have crated many PCBs with orcad over the years. However i had learnt orcad on my own.

Recently i got a email from my PCB fabricator:

Quote:

In masking you provided zero clearance. In future designs please provide min. 16 mil extra than the actual pad size. We have increased the making pads and re-ploted the films.

Is there a way by which i can increase the pad size for the masking layer during the Post Process stage?

Regards

Rodney Almeida

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I don't use OrCAD, but any PCB software should do that automatically. The Pulsonix software I use definitely does it.

Leon

Leon Heller G1HSM

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OrCAD does not do that automatically. You have to specify it in the footprint, or rather the padstack. You can change it in gerber data, but that is a sucky load of work.

Change the footprints, they are wrong. But how much all depends on the manufacturer. I hope they mean that the mask hole shall be 16mil larger than the pad, 8mil on each side. I always add 100um (4mil) to the hole width in the mask, so that I get 50 um (2mil) distance between pad edge and mask edge.

If the software does it it self, how do you know/set how much it is? What do you do if you want another shape of the opening? I think that this part works quite fine with OrCAD Layout. Thou you have to have some understanding in the manufacturing of PCBs to set all the parameters right. Well, a lot of understanding... Hopefully the manufacturer complains when you do something wrong.

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Quote:
But how much all depends on the manufacturer.

For shure, because for me they never asked me that.

Regards,
Brunomusw

Regards,

Bruno Muswieck

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With Pulsonix it's set up in the Technology - the Solder Mask layer class has a setting for pad oversize (absolute or percentage). Default is 5 mil.

The OrCAD technique sounds as though it could be useful in certain situations, but how often have you required a custom clearance on a footprint?

Leon

Leon Heller G1HSM

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In the gerbers, you can probably isolate the pad flash elements and change the sizes, if it's too hard to change it in the design.

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brunomusw, some (or most?) manufacturer fix the boards so that it works for their processes. When I was making one of my first PCBs Olimex even moved around some traces and added vias. They probably saw it was a n00b PCB, and thought it was OK. And it did work so I was happy.

leon_heller, different BGA ball sizes should have different solder mask opening to get a good solder.

When you make the pad you set the opening same way you set how big the pad is, it's easy as that.

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It depends on whether the BGA pads are soldermask-defined or not. Non-soldermask-defined pads are more reliable.

Leon

Leon Heller G1HSM

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AgwanII wrote:
brunomusw, some (or most?) manufacturer fix the boards so that it works for their processes. When I was making one of my first PCBs Olimex even moved around some traces and added vias.

Man, that would be an immediate FAIL for me with a board vendor. I have a strong rule there, "DO NOT CHANGE MY GERBERS". Many of my boards would be either impossible to put the usual little board shop token on, or putting it on would alter/break the board functionality.

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I've dealt with Olimex and I can't believe that they would do anything at all to anyone's files. If anything is wrong they reject them immediately.

Leon

Leon Heller G1HSM

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yup, I guess in Orcad the only way for changing the mask size is to change the parameters of the Padstack.
Lucky for me my fabricater made the small changes for me directly to the gerbers.

Are they any good Free gerber viewers/editors out there?

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Olimex even has a small charge for fixing small beginner errors.

Quote:
REMOVING SMALL BEGINER ERRORS (IF AT ALL POSSIBLE): +EUR 3.00 per pcb job (removing overlaping drills, adjusting size for panelization, no panelization drawing picture, polygone fill with under 8 mils line width)

Taken from olimex homepage.

Changes for other serious PCB producers would mostly be about board edge. I have had my edges changed a few times, but then the manufacturer has always called me first.

But if they see that it is a really n00b PCB I guess they might just change things that they think does not affect functionality.

I often attach a specification with the order for the PCB where I say they have to make the PCB as the gerbers and if they want to change anything they need to contact me first. I also specify stackup, board thickness, material and other in this document.

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I haven't used Olimex for a couple of years, they seem to have changed their policy. They once rejected one of my boards for an insufficient track clearance at one point; I couldn't find anything wrong with it, got a demo copy of the checking software they use, and found it had a bug!

rodney_alm:

I use the free version of GC-Prevue for checking Gerbers, but the paid-for version is needed for editing.

Leon

Leon Heller G1HSM

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Because of all that, I thinnk that is good to have a good relationship with your PCB manufactor...
First depends the quality, then price and then relationship that sometimes this could be second insted of price.

Regards,
Brunomusw

Regards,

Bruno Muswieck

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I am a new user of ORCADE.Now i want to insert a JTAG Connector to my own schematic..the problem is that i am not able to find it in part list and library as well.so kindly guide me in this regard and suggest me any option so from where i can get this connector?

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Either you fight Orcad, or you work with Orcad. It took me about two years of fighting until I finally gave up. I now draw all my schematic symbols and layout footprints my self. It is so much faster and becomes so much better than hunting for symbols and footprints that aren't correct anyway.

I'm sorry for this answer, I know I would have hated it too a year ago or so.

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Pentalogix Viewmate is free gerber viewer

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I too always draw footprints myself, though I hate the job, mostly because most datasheets dimension footprints in a difficult way.

Regarding the soldermask oversize, there is a way to increase all sizes in all padstacks in one go:

* Open the padstack spreadsheet (Shift-T)
* Select all padstacks by clicking on the 'Padstack or layername' header in the left-top corner
* Right-click and select 'Copy layer...'
* Select SMTOP for both Source and Target layer, fill in the required oversize
* Click OK

Repeat for SMBOT, if required.

I have dealt with a number of PCB houses and they never required me to have soldermask oversize.