Re: gEDA-user: Interesting board defect

[Stefan Salewski <mail@xxxxxxxxxxxx>]

Am Montag, den 16.02.2009, 18:53 +0000 schrieb Kai-Martin Knaak:
> 
> Some remarks: 
> 
> * 4 Layers will take 12 working days minimum, plus what ever it takes for 
> fedex to ship from china. If you don't register for "open account" 
> payment needs to be confirmed before production time begins.
> 

Yes, boards from china will take some time.

> * Shipping and customs and EUSt have to be added on top of the quoted 
> price.
> 

Yes, but total costs are still not bad. If I remember correctly: Four
boards, 4 layer, each 26cm * 32cm will give total something about 1000
Dollar. The only company which I aware of here in Germany which is not
much more expensive is http://www.microcirtec.de
Large quantities are really cheap at pcbcart, so I think it is a good
idea to try them.  

> * There is a maximum number of holes. (300 for my 100x100mm test case)
> 

I think this is no problem, most people use at least some SMD.

> * Design rules are modestly aggressive:
> 	minimum drill = 0.4 mm
>   	minimum track width, minimum spacing = 0.2 mm
>         minimum annular ring = 0.25 mm
>   My preferred fab offers about 0.75 times these values as standard.
> 
> * Poor english on the webpage. E.g: "For small quantity, if by air the 
> extra cost will make it not save" (no full stop). 
> 

My english is poor also -- perfect fit :-)

I think their parameters are not too bad, and I think they can do
better, for more money. (And I think drill is 0.3mm without additional
costs, think I have seen it...)

>   
> > I think they have no information for impedance control on their page 
> 
> There is an item "impedance control" in their quote. I'd guess, this 
> could be set this to some other value on request. 
> 

I have seen this, but do not understand it.

I have asked by email some months ago, and got only a very short reply:

>Hi Mr. Salewski,

>Thanks for your suggestion, we are considering improving our homepage.
>Regarding to your question, please see follows:
>Trace width: 8.5mil, 1oz copper, 0.12/1.13/0.12 for 50ohm impedance.
>Best regards

Not much. I guess that I will get 50 Ohm impedance for traces on outer
layers of 4 layer board if trace width is 8.5 mil. Hope that I really
will get this.


Best regards

Stefan Salewski




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