This continues my earlier post.
About OSHPark
Here is an Element14 article about the OSHPark business model and company history.
Briefly, it says that OSHPark adds value for small makers by aggregating small boards from many customers into large boards that PCB manufacturers are equipped to make. Some of added value is the software that runs the OSHPark business: the web store, the software that aggregates many small PCB designs into a larger one, the software that understands and converts many different design file formats.
I appreciate their work and wish them continued success.
OSHPark and ad hoc panels (without frames)
A panel created according to my earlier post does not have any explicit support tabs or a frame. I will call this an ‘ad hoc panel.’
OSHPark adds support tabs for you, between the PCB’s of your ad hoc panel. (They also add support tabs on the outside of your panel, to the adjacent customer’s board or panel in the manufactured, huge, aggregate board.)
Unfortunately, OSHPark might also break apart your ad hoc panel at their convenience or need. OSHPark breaks apart their aggregate, huge panels into customer’s boards. While they are doing this, they don’t know which groups of boards are a customer’s ad hoc panel. So OSHPark may break apart your ad hoc panel.
Just looking at the aggregate panel pictured in the above linked article, you can see that it might be difficult for the person separating customer’s boards NOT to break apart your ad hoc panel.
My point is: if you want your panel to stay together, you need to add a frame. Otherwise, you are taking your chances. The frame is what tells OSHPark not to break apart the boards.
Why create panels?
- so you can save labor by stenciling or assembling boards in panels/batches
- to save board costs by nesting odd-shaped boards
For the first purpose, the fact that OSHPark may break apart your ad hoc panel might defeat the purpose. In my experience, making panels of 3 small boards, to stencil them by threes, for hand pick and place, it has not been a problem. If OSHPark breaks apart your ad hoc panel in odd ways, you can always break them into individual units and stencil them by ones (using a corner of the same stencil for the whole panel.)
As I mentioned in an earlier post, OSHPark doesn’t always break your multiple board order into individual boards. Sometimes you get ‘happenstance panels’ even if you did not order an ad hoc panel. (Assuming your boards are much smaller than OSHPark cardboard shipping envelopes of about 5×7 inches.)
I am not really serious about volume production yet. If you are, you should frame your panels.
Nesting odd-shaped boards into ad hoc panels
Say you have an L-shaped board. OSHPark calculates the cost from the bounding rectangle. That is, they will charge you for the empty space between the arms of the L.
If you nest two such L-shaped boards into an ad-hoc panel, the cost for the bounding rectangle of the panel will be less than twice the cost of the individual boards.
Other words for nesting are tiling or bin packing.
Tiling is partly how OSHPark subsidizes small makers, by fitting small boards into the wasted space of larger, odd-shaped boards. If you create your own tiled, ad hoc panels, you save costs, but then someone else might be less subsidized.
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