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Questions relating to designing PCBs
By propellanttech
#30959
EDIT: I changed the name of the thread. Since this is an absolute now...and not a possibility.

If your interested, watch for threads with LB SMT in the title. /EDIT


I'm a new business owner (actually started it myself last year).

I'm looking to possibly offer surface part placement.

I'm wondering who would be interested.

I'm not sure of the rates.....but the way I'm looking at doing it is as follows:

There will be a setup fee for a new board design. (thinking about 10-15 bucks)

Placement fees will be according to pads. (certain price for each pad)

If the design changes (minor change....moved part, added part, removed part) there will be a small design change fee (this is based on previous orders)

I'm looking at people that will have small volume runs. 5-100 boards per run.

The problem.....it would be impossible to totally test the assembled board. Also....the parts would have to be supplied.

Let me know your ideas and opinions,

James L
Last edited by propellanttech on Sun Feb 10, 2008 5:13 pm, edited 2 times in total.
By jasonharper
#30968
I can imagine using this service, depending on what the "certain price for each pad" turns out to be...

Will customers be required to provide a solder paste stencil?

What's the finest pitch/smallest package size you'll deal with? I suspect you may eventually want to have this be a factor in the price - placing a 1206 is not the same thing as placing a 01005...

What sort of guarantee will you offer (for example, if you accidentally place an expensive BGA upside-down, and the customer doesn't have the equipment to rework it themselves)?
By propellanttech
#30972
Jason,

No stencil needed.

I'm looking at 0402 as the smallest. I may go as low as 0201. I know it will not be smaller than 0201.

No....I probably won't calculate the size in the price. I'm not sure at this point how to do the calculation, but I know the more boards you have done....the cheaper per pad the price will be.

Just because something is smaller is not necessarily the case....they get to only have two pads when they are small. A 44 pin QFP would be more expensive than a 0201 capacitor. The reason....if the capacitor is placed wrong.....the rework is not that hard ( less likely to toast an expensive part). If a 44 pin QFP is wrong.....possibility of toasting a $10 to $150 part.

I guess I should state this will be done with a automatic pick and place machine.....not by hand....so the difference between a 1206 and a 0201 is negligible with respect to the machine. The post inspection is a little more difficult, but the machine will be able to accurately place the smallest size when determined.

That is why the pad calculation is better than the size.

I will rework the board for free. I'll pay shipping.

But at this point....this the view point I have.

James L
By Philba
#30976
I could see using your service though cost is clearly going to be a significant factor.

The number of pads is a reasonable way to make pricing easy though I don't see it as totally fair. placing 3 soic20s is going to be a lot less work for you than placing 30 1206s. I would think you would want to price more by the number of components. I get the rework argument but how much rework from place errors is common? I was under the impression that, with a solder mask, ICs are pretty well self aligning once you get them in the ballpark.

I would guess your set up fee is way low.

What ever you do, make it easy for someone to calculate the cost up front. When I'm shopping for a service, I make my first pass with out talking/emailing to the candidate companies. last thing I want is a bunch of sales types calling me up.

How do other shops price jobs?
By propellanttech
#30981
Philba,

I placed the setup low....because I think people will appreciate having more than one design built.

The problem with component number pricing is the solder. The more pins the more solder that is used.

I agree placement rework is low......if the user doesn't put the part backwards.

I'll try to make the setup pretty easy.

I'm just asking to see if I'll even offer the service.

James L
By propellanttech
#30989
I'm thinking about the pricing... let me know what you think about this:

for 5 boards (probably be the minimum I will do)

$25 setup (this is one time as long as nothing moves or changes)
$0.15 per pad

Plus shipping.

The price will go down if you have more than 5 boards mounted.

Tell me what you think,

James L
By chrisjp
#30993
I'd consider it if you support QFN, but .15$ for pad gets expensive pretty quickly.. Adding a 100 pin FPGA in LQFP -> 1 place, 15$...
By mtwieg
#30994
I always wondered what the logic was behind charging per pad as opposed to charging per component. I never thought of solder paste as that big of a price issue. Is paste really that expensive? And even so, number of pads isn't a very accurate way to estimate the amount of soldering required. A D2pak with 3 pins probably requires as much as a 48 pin tqfp. Ideally, I suppose you could make some program that could determine the exact total area of the pads from gerber files, but I'm not sure how feasible this is.
By chrisjp
#30995
I was curious what other companies charged and hunted around a bit. A Canadian company didn't have their setup/stencil fees listed but charged:

"$0.0125 per pin for SMD
$0.025 per pin for DIP, PTH components."

But 25$ setup is certainly lower than what they charge.
By propellanttech
#31020
chrisjp wrote:I'd consider it if you support QFN, but .15$ for pad gets expensive pretty quickly.. Adding a 100 pin FPGA in LQFP -> 1 place, 15$...
Chris for a 5 board run....I think $15 for a 100 pin FPGA is pretty cheap.

Considering what is required to place one accurately. I will be able to place components down to 20 mil pitch. I'm not sure your part will fit into the limits, but you could check.

James L
Last edited by propellanttech on Thu Jun 07, 2007 8:51 am, edited 2 times in total.
By propellanttech
#31021
mtwieg wrote:I always wondered what the logic was behind charging per pad as opposed to charging per component. I never thought of solder paste as that big of a price issue. Is paste really that expensive? And even so, number of pads isn't a very accurate way to estimate the amount of soldering required. A D2pak with 3 pins probably requires as much as a 48 pin tqfp. Ideally, I suppose you could make some program that could determine the exact total area of the pads from gerber files, but I'm not sure how feasible this is.
I think you are confusing the issue. The D2pak is much easier to place accurately than a 48 pin tqfp. Which is more likely to require rework. Also since there is no stencil (the machine will have to dispense paste) which will take longer to dispense? Time is money with any service like this. Machine time is very expensive.

But remember....I'm only talking about a 5 board run as an example.

James L
By propellanttech
#31022
chrisjp wrote:I was curious what other companies charged and hunted around a bit. A Canadian company didn't have their setup/stencil fees listed but charged:

"$0.0125 per pin for SMD
$0.025 per pin for DIP, PTH components."

But 25$ setup is certainly lower than what they charge.
I think that is a pretty cheap price.....but you didn't list their minimum run. I'm sure they will not do less than about 500 boards per run. Most assembly services have large minimums.

I should also state, I'm not going to do wave soldering. I'm not interested in DIP or through hole component placement. I don't think anyone really needs this service....and would be hard to price for anyone to use.

I'm only doing SMT....and only smt pads will be counted.

(Not directed at Chris)

The following would be the maximums:

40mm maximum component size
0402 minimum component size
20 mil lead pitch
17" x 13.75" max PCB size (this can be panelized boards)
Not sure of the minimum PCB......
Fudicials are required

I'm enjoying the discussion.......maybe worth my time to offer this service if we can come to some type of compromise.

James L
Last edited by propellanttech on Thu Jun 07, 2007 11:21 am, edited 2 times in total.
By chrisjp
#31025
Yep, the site didn't list their minimums either so I certainly agree with you.

I'm just not sure doing it per pad is going to work out in the long run.. Places like screaming circuits (you can quote 10 boards here) charge per smt, per fine pitch placement, regardless of pin count.

Just as an example, I have a board with roughly 350 pads from 5 devices, and would want between say 10 and 40 boards assembled.

Screaming price: 10 day turn.
10 - 445
15 - 505
20 - 566
40 - 807

Your price:
Per board - 52$ + 25 Setup
10 = 520
15 - 805
... etc.


I assume this is as they are using a stencil and most of the cost is up front. However, I think you'll be hard pressed to hit the prototyping market with quantity > 5 and roughly 50$ boards per setup and you won't hit the production market with high per pad pricing. Just my opinion though.

I'd love it if i could send off 10-20 boards with bga/qfn's and have you slap them on however, I assume x-raying will not be an option.

Just some thoughts, and I hope if you decide to start it that it is a huge success :)
By chrisjp
#31026
I should add that I did see you mentioned a price cut for > 5 boards, but it would have to be a ~50% price cut at q15 to be competitive. I just don't see how that would be possible if your fixed costs don't go down, no stencil. But anyways, enough babble :)
By propellanttech
#31027
chrisjp wrote:Yep, the site didn't list their minimums either so I certainly agree with you.

I'm just not sure doing it per pad is going to work out in the long run.. Places like screaming circuits (you can quote 10 boards here) charge per smt, per fine pitch placement, regardless of pin count.

Just as an example, I have a board with roughly 350 pads from 5 devices, and would want between say 10 and 40 boards assembled.

Screaming price: 10 day turn.
10 - 445
15 - 505
20 - 566
40 - 807

Your price:
Per board - 52$ + 25 Setup
10 = 520
15 - 805
... etc.


I assume this is as they are using a stencil and most of the cost is up front. However, I think you'll be hard pressed to hit the prototyping market with quantity > 5 and roughly 50$ boards per setup and you won't hit the production market with high per pad pricing. Just my opinion though.

I'd love it if i could send off 10-20 boards with bga/qfn's and have you slap them on however, I assume x-raying will not be an option.

Just some thoughts, and I hope if you decide to start it that it is a huge success :)
I see your point...... That wouldn't be good in your situation.

Hmmm.......I agree....the pricing is going to be more complicated.

Let me think about it some....surely I can come up with something that will fit the bill.

I very seriously doubt I will offer x-ray as an option...... :-)

James L
Last edited by propellanttech on Thu Jun 07, 2007 10:18 am, edited 1 time in total.