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PCB Fab House for 3mil Traces? — Parallax Forums

PCB Fab House for 3mil Traces?

Duane DegnDuane Degn Posts: 10,588
edited 2013-06-14 23:05 in General Discussion
I purchased a couple of the tiny cameras used in the Parallax Laser Range Finder in hopes of making a small PCB to interface with the cameras.

These cameras have a tiny ball grid array on them.

Here are the traces from the gerber files of the LRF.

attachment.php?attachmentid=102268&d=1371269405

The fab houses I've used all have a limit of 6mil for traces with 6mil spacing between traces.

This is what the grid looks like with 6mil traces.

attachment.php?attachmentid=102269&d=1371269406

Obviously 6mil traces don't leave a 6mil space between the pad and the trace.

It appears Joe Grand (who designed the LRF) used 5mil for most of the traces to the camera but these traces narrowed to 3mil when they needed to squeeze between the pads for the ball array.

The array is 0.5mm pitch.

I have not idea is I could successfully solder this part to a properly made PCB made but I'd like to give it a try.

Any suggestions on a fab house to do this kind of work?
TracesLrf130614a.PNG
503 x 587 - 18K
Traces0_15mm130614a.PNG
420 x 471 - 10K

Comments

  • NWCCTVNWCCTV Posts: 3,629
    edited 2013-06-14 21:35
    I am not able to help on the question but have a question of my own. Where did you purchase the cameras from? I have been looking for something small and those might fit the bill. Thanks.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-06-14 21:53
    NWCCTV wrote: »
    I am not able to help on the question but have a question of my own. Where did you purchase the cameras from? I have been looking for something small and those might fit the bill. Thanks.

    These are available from Digi-Key. These were mentioned in your thread about cell phone cameras but I don't think you were very interested since they don't produce a video signal.
  • SRLMSRLM Posts: 5,045
    edited 2013-06-14 22:24
    Advanced Circuits can do down to 0.00275" width and spacing: http://www.4pcb.com/NEW-Capabilities-Brochure-Feb2013-ForWebsite.pdf

    I've never tried this, but you might consider adding vias in pad to go down to another layer.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2013-06-14 22:27
    SRLM wrote:
    ... you might consider adding vias in pad to go down to another layer.
    In-pad vias would wick solder away from the ball grid.

    -Phil
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-06-14 22:39
    Phil Pilgrim (PhiPi) wrote: »
    In-pad vias would wick solder away from the ball grid.

    -Phil

    Another problem with in pad vias in this example is the minimum hole size and annular ring (of the fab houses I've used) are huge compared to this grid.

    Thanks for the Advanced Circuit's suggestion SRLM. I'll see what it would cost to have them make some boards.
  • LeonLeon Posts: 7,620
    edited 2013-06-14 23:05
    In-pad vias are filled to prevent them wicking solder.
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