PCB Fab Confusion

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AtomSoft

Well-Known Member
Im LOST! i was considering getting some PCBs done in a FAB HOUSE now i see they say like 10 sq inches

Do they mean 10" x 10"?

i know its probably a dumb question but i see places with 100 sq inches also..

Example site:
PCBFABEXPRESS Printed Circuit Boards and PCB Assembly

if my board is 2" x 2" does that mean i can get 25 boards made from 10 sq inches?
 
[squared inches] = [inches squared] = in^2

It is a unit for area, and not part of the number. Think about it, a PCB that is...10"...long? Doesn't make much sense.
 
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look here then:

**broken link removed**

155inch sq

If i have a board thats 2.3 x 1.5 = 3.45 sq" correct... if so then 155 / 3.45 = 44.927

so i should get 44 boards? Can you explain that if its wrong... thanks heh
 
It is my understanding that the most common panel size in the industry is 18" x 24", with a usable area of 16" x 22". If you are dealing directly with a fab, just ask them what their standard panel size is and figure out how many boards can fit onto one. My last order with DDI Global utilized one panel. I was quoted $1930 for 5 boards, $1930 for 10 boards, or $2150 for 30 boards including electrical test. This is because my (custom stackup) boards were going to be made using one panel, so the extra 20 or 25 boards cost virtually nothing extra (a whopping 120 dollars more total) because all that was involved was a little more effort in electrical test and they had to worry about yield a little more.

Now other fab houses might put your stuff on a panel with someone else's stuff if your stackup (dielectric, copper thickness, plating, soldermask, tolerances, etc) are the same. Advanced Circuits and other inexpensive places that let you buy only a few boards do this. When these guys say 10 square inches, it means 2x5, or 2.5x4, or similar, and definitely not 10x10.

If you're board is 2x2 it means you can get two made in 10 square inches (2x2x2 = 8 sq inches).
 
AtomSoft said:
look here then:

**broken link removed**

155inch sq

If i have a board thats 2.3 x 1.5 = 3.45 sq" correct... if so then 155 / 3.45 = 44.927

so i should get 44 boards? Can you explain that if its wrong... thanks heh
Click to expand...

Yes, that is correct.

That's why if you only need one or two boards, it's important to look for fab houses that deal with low setup costs but high unit cost (like BatchPCB). Then small quantities are cheaper. However, if you do the math you'll find that type of pricing gets very expensive when you need a few of the same board in which case you're better off looking at a standard board house (high setup cost but low unit cost). In which case it often costs you about the same price to get 1, 3, 5, even 8 boards.
 
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This is what i am scared of heh paying $$$ for 2 boards would suck! heh

dknguyen i hope its the way i stated heh
 
OK I just read the page you linked to (you beat me by one minute ) and they do 14.5 x 10 size panels, so you can do 6x6 grid on that for 36 boards or 9x4 grid for the same 36 boards.

Remember you have to account for the unusable area, so actually think what the PCB layout grid would be on that size sheet.
 
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Yeah, a good example is that for more complicated PCBs (like 6 or 8-layers) it costs the same (about $600-$800) to get about 1-8 boards made. $100 a PCB is reasonable for 8-layers I think, but the question is...as a hobbyist can you find a way to make use of all 8? Certainly, if you just order one then you'd be paying $800 for a single 8-layer board which is...unreasonable to say the least lol.
 
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heh i think thats crazy but heh i wouldnt go that far. 2 or 4 layers is most i would ever use. 2 is normal. If i start XMOS this year then 4 will be normal heh... but anyway if i can get 44 boards for about $200 thats $4.50 a board or so ... and parts for 44 boards would cost me about $440 then add the $200 for boards thats $640... aka $14.5 a board or so if i sell them at $25 a pop thats $1100 totals income - cost of stuff... $1100 - $640 = $460 in profit or $10.50 a board... you think its worth it? like is this normal in business ?

More like is it good profit?
 
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I had a US quote for boards: $770.00

The quote from China was $230.00 including overnight delivery.

Who do you think I chose?
 
yeah i rather use a large LQFP or something than FPGA... many electronics with FPGAs get damaged by bad soldering (REFLOW) .... even happened to XBOX 360 systems
 
thx pommie. I forgot about them. I was registered already heh

$ 1.44 per board... $ 90.32 total for 40 boards which is nice!! 8 day service
 
heh i know that but doesnt add to cost much... since i can split the $40 frieght by 40 boards... thats $1 extra each. Lets say total is $140 now / 40 = $3.50

If i sell for $15 each then i make a huge profit... Which is still great!!
 
AtomSoft said:
yeah i rather use a large LQFP or something than FPGA... many electronics with FPGAs get damaged by bad soldering (REFLOW) .... even happened to XBOX 360 systems
Click to expand...

Some of that is blamed on the no lead solder, which is not as flexible as leaded solder. Still, that is large BGA's.

If you use Gold Phoenix, you just give them your gerbers/drill for your one board and they will panalize for you and you'll get as much as they can fit on. If you board does not exactly match the production sheet on the x and y axis when tiled, there will be some throw away.
 
AtomSoft said:
look here then:

**broken link removed**

155inch sq

If i have a board thats 2.3 x 1.5 = 3.45 sq" correct... if so then 155 / 3.45 = 44.927

so i should get 44 boards? Can you explain that if its wrong... thanks heh
Click to expand...

Why don't you try PCBWING?
 
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