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 Post subject: Components on inner layers of multilayer PCB?
PostPosted: 05 Apr 2017, 13:29 
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I am working on project in which I would like to put components on the inner layers of the PCB. The layers leading "down" to the desired layer (it could be anywhere between a 4 to 8 layer board) would have cutouts such that it exposes the land pattern for the component to be soldered. I've included a quick drawing done in Solidworks to demonstrate what I'm looking to do. At first I thought this would be "no big deal" however it seems that DP only "expects" components to be on the top or bottom layer. If one could place components on any layer I think that would take care of the issue, but I don't see a ready way to accomplish this. Is there a way to do this? If I need to I suppose I could contact the board house and make them aware of what I want to do with individual layers that they then stack up (a trainwreck I'd rather avoid), but it would be really, really helpful (and cool) to do this inside DP and output the 3D file.

Any tricks, suggestions are welcome.

Thanks,
Mike Tripoli


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 Post subject: Re: Components on inner layers of multilayer PCB?
PostPosted: 05 Apr 2017, 14:02 
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Ok, Mike, I really haven't thought this through but did have this random thought...

I'm pretty sure that this isn't possible 'natively' with Diptrace since you can't put pads on internal signal layers, but couldn't you just treat this as 'several' individual single signal layer files, export the gerbers, rename them and then have the board house stack them up?

The big question is can the board house FIRST route the individual layers and THEN stack them up. I've never heard of that but I guess you could ask. I think they would have issues with shorts when it came to the 'plate through' step though.

No idea if this would actually work but if the board was simple enough that you didn't have to rely on 'verification' steps it 'might' work?? dunno..

Jeff


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 Post subject: Re: Components on inner layers of multilayer PCB?
PostPosted: 05 Apr 2017, 21:56 
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Hi Jeff,

That's pretty much what I had alluded to in the post. I can do exactly as described and then create the Gerber myself (with Pentalogix). After I posted the question I did a bit more research on this. As it seems right now, designers are starting to think along these lines and near as I could tell the purveying propaganda was that Mentor Xpedition could do components on any layer. I feel for tool makers like Diptrace (sometimes ;^} I found a bunch of people investigating the same ideas as I have; with components reaching such small packages, proposing something like I drew is child's play (with open channels down to the component level). The real fun will begin when the components are different layers and soldered in place on that layer----now we're talking!

I'm looking at alternatives; back side mounted LED's are a choice. The down side is "that" surface is no longer flat.


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 Post subject: Re: Components on inner layers of multilayer PCB?
PostPosted: 05 Apr 2017, 23:51 
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Applying solder paste (???) and placing the components? Yeah... looks like it might have to be done by hand if it could be done at all... unless you had one of those CNC paste dispensing syringe thingies and a PNP that could handle the different levels... hmmm...

mtripoli wrote:
I'm looking at alternatives; back side mounted LED's are a choice. The down side is "that" surface is no longer flat.


Yeah, that would be the obvious choice.


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 Post subject: Re: Components on inner layers of multilayer PCB?
PostPosted: 06 Apr 2017, 11:22 
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Nahhh... I was a consultant at Powerex (power semiconductors) doing some work with integrating low-level voltage control with the high voltage devices in the same package. One of the techniques we used was preforms for solder (literally, little preformed solder pads) that can be machine placed. The heads on the PNP can easily place the components on any level. So, it really comes down to working through the process that the PCB is "partially" built, components placed, then another layer... Not a process we have now, but then again, I never expected to see components so small (0402) that one could prank a friend by filling a pepper shaker with them... ;)

I'll work through the design as "single layers" and go from there...

M

P.S. This is an idea for "one off" or small runs designs so I'll do all the placement by hand anyway.


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