fixed negative LDOs

Den torsdag den 20. april 2017 kl. 05.22.21 UTC+2 skrev John Larkin:

Sometime you can also put test connections on the outer region so you can do test on whole panels of boards.

this is a neat trick:

I use an old rusty hand-operated sheet-metal brake/roll/shear, a cheap Chinese thing about 30 years old. We also have a nice foot shear that I'm not allowed to use on FR4.

He could have run power bussing inside the array, and just let them break later.

Den fredag den 21. april 2017 kl. 22.05.43 UTC+2 skrev John Larkin:

to break them apart you need score lines, the score lines cut the tracks

I was thinking inner layers, but maybe he's just doing double sided.

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it is probably just double sided, but even with more layers I'm not sure yo u can rely on the depth of scores to be just right to avoid the inner layer s

It's not 100x150. You're talking about a full panel anyway. It would probably cost a bloody fortune to get a two-up panel, even if you could do something with it after you got it.

Yeah, we panelize at the Gerbers. They aren't allowed to change anything.

They just got us an Altium license for the engineers to do test circuits. I may try to learn it to make some test fixtures but there are so many other things I want to get done.

That's certainly dependent on the stackup. High speed boards tend to have a thick core with prepreg layers built on that but it's possible to have even cores between layers or two cores with prepreg between. Whatever you're willing to pay for.

These days we seem to panelize the majority of boards- this is a

On tiny boards it reduces the handling significantly even if hand assembly is used. You can get a bit better PCB price if you allow bad boards within a panel, and in that case you should add some silk screen to allow them to X-out mark the bad board.

The top/bottom scores between boards and tooling strips can be just snapped carefully by hand, but it's a lot nicer to have a machine like John's.

If you panelize it yourself it's not hard (in Altium at least) and you have complete control over everything.

--sp

Good point. We'll note that on the fab drawing or PO.

Speffball? A new Canadian sport?

I've only seen a big black X drawn over the whole board with a pen

I think for the most part we use "mousebites" rather than scoring

We usually ask for a "solder sample" with each batch of boards. The board house disfigures that one with some super marker, or punches a hole in it.

Yes, I've seen it done with a Sharpie.

There can be problems with cracks if you break the scores. If you saw or shear them, why bother with the scores. We also use mouse-bites. I use a fine-tooth hacksaw blade to separate them cleanly.

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seems silly to ruin a working board

It's theoretically a bad board, and theoretically free. So they don't want us to use it.

I think board houses make a few extra per run, to allow for some defects. One board house called us and offered us about 50 boards, extras from various previous runs, cheap. They said it was to fund their Christmas party.

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yeh if you order 10, they have to make extras to make sure they get 10 working boards.

I've seen some of the cheap proto shops adding a cheaper option of getting "roughly 10", on a bad day you might only get 9, but you get all that works usually several more than 10

PCBWay usually ships us about 10% more boards than we order.

Cheers

Phil Hobbs

He's talking about using a non-functional board. However, we only get good boards so one or two are used as solder samples. No big deal.

Hockey and curling are the only sports we really need.

--sp