4 layers VS 2 layers PCB cost AND carbon printing ?

[kennyden]

Hi,

Question #1:

I'm currently using a 2 layers board for my prototype. Obviously, the design would be much cleaner if I'd be using 4 layers. However, having a seprate ground and power plane for a 6 inches sqr PCB is what I beleive to be luxury.

Nevertheless, how much more should I expect to pay for a 4 layers vs a 2 layers ? I used to work with boards that had 16 layers and what we found is that there was a 20% cost increase per added layer. However, this rule of thumb applies for a multiplayer board. Would passing from a 2 layers to a multilayers (4) process the same price increase (I doubt it).

I've seen sometimes 100 to 200% increase from 2 to 4 lyrs but these were for protos qtys. The volume involved here are more in the 500 to ++ thousands range. I'm using 8 mils traces, 29R15 vias so nothing too fancy.



Question #2

anyone has experience with a good PCB supplier which can do carbon printing ?


Thanks all.

 

[buzzp]

I have typically seen the cost increase 50%-200%, depending on the board manufacturer. There is a lot more to do when going from two layer to any additional layers.

 

[kennyden]

Yep, these were my numbers too. There was a myth circulating here that it was not that much more expensive. I just wanted to put a number to the "that". I think I'm gonna stick to the 2 lyrs unless I really need to do otherwise.

Thanks buzzp.

BTW, anyone knows of a good PCB fab that does carbon printing for PCB traces (used for keypads) ? I found some in Asia but any good in USA or Canada ?

 

[nbucska]

Search e.g. at <

http://www.dogpile.com>

for "PCB,carbon printing"
( no"") and you will find a BUNCH...

Is is necessary to use 4L ? 2 is cheaper and if it is good enough, why to pay more? You may be more careful with the design, do more manual routings etc.

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[kennyden]

Thanks nbucska.

 

[nbucska]

Ther was a few years ago a 'bustrip' on the market-
a .15-.2 inch wide metal strip with pins at every .5 to 1 inch. It may be much cheaper to add one of this to the GND than an extra layer. ( I don't know its name.)


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[logbook]

Nbucska,
perhaps you are thinking of something like Mektron bus-strip.


rs

http://www.com

part number 435-715.

 

[nbucska]

Similar, the one I used had pins at every inch

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[sreid]

Roughly these days (in some quantity) 4 layer costs about twice 2 layer. But if the size can be shrunk using 4 layer the boards will be proportionally cheaper. And smaller can be a sales advantage.

Many designs are driven to mutilayer because they simply can't be routed on two layers.

 

[kennyden]

I will finally stick with a 2 layers PCB. I have managed to add some GND and VCC copper pours which will do the job compensating (as far as trace inductance goes) for the missing planes...

However, I've shopped around and found that some Asian cies do offer 4 layers at about 50% more (compared to 2 lyrs) which is not too bad when your board cost around 2 $. Besides, tooling cost is even the same ?!

Anyways, even 58% on a 2$ PCB is too expensive for high volume prods.

Thanks all for your comments/feedbacks.

 

[buzzp]

Its hard to compete with the Asian board houses. The only thing that bothers me about these places is the child labor and the potential shipping problems that can occur. But hey, what can you do? You have to stay competitive price wise so you are almost forced to use these sources because they are much less expensive than any north americal board house.

 

[kennyden]

Ooohh buzzp, now you're touching a very hot topic these days. I totally agree with you however just look around you and there's asian stuff all around. How do you think WalMart has gotten so big ? How about Nike, Home Depot and all the rest... Most of the stuff we buy these days from clothing to tools to video or audio equ etc.. is done in China, taiwan or India. Even north american technical support from some of the big names like Intel and IBM is done overseas.

I'm telling you, either we go in Asia or we may be forced to go out of business it's that simple. For those who will say that you don't get much quality from Asian products, think again. Most of them are ISO9001-2000 and are putting much effort into improving this side of their business. It is becoming veeeery scary ! Well, I would have to say much on this but this is not the place to discuss this. But again you're right, many of the asian people are exploited and this is bad. Until our governments do something about it what can we do ...

Regards

 

[buzzp]

Thats what I am saying, your almost forced to go over seas with PCB's because the cost is so low, even when you add shipping (and several do not charge shipping). Your competitors are doing it and thereby able to reduce the cost. If you don't, then your margins go down. I have no complaints about the qualitity of over seas boards either.
Good luck to you.

 

[ScottyUK]

OT a little, but in reply to Kennyden,

ISO9001 and its cousins ensure that a company defines a procedure and that the procedure is followed. Ergo, if a company writes a procedure for making useless crap and follows that procedure so it churns out useless crap of a consistent repeatable standard, it can wear the ISO9001 badge. It is no guarantee.

I've worked in companies where the ISO9000 system - BS5750 as it was in the early days - was implemented to a high standard and we got tremendous benefit from it once it was up and running. I presently work in one where the implementation is awful, creating a bloated paperchase which brings little or no improvement in quality, while slowing progress to the speed of molasses running over a cold rock. As with most things, a quality system is only as good as those who implement it.



----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[kennyden]

Don't get me wrong, I have worked for cies that were ISO9001 and the new one 9001-2000 (besides having been audited many times for these standards, which is BTW a pain in the... ) and ISO DOES NOT define a quality standard as such BUT at least you can audit your ISO customers and see if what they do is according to your quality standards. If not, you just go elsewhere.

My point was, asia business in the past was not so good quality wise but things are changing as more N. American cies go do business over there. So Asia is not to rule out anymore and must definitely be considered.

Thanks for your comments.