Effects of reducing copper thicklness from 1 oz to 1/2 oz

[Anonymous_Ricky]

Hi All,

we have to reduce cost of one our PCB.

It is 4 layer PCb with 1oz stackup.

we are planning to make it in 1/2 oz but our concern are (Power is not an issue as it is manageable):

1. how much cost effective will it be?
2. will there be any EMC issues due to this? I am unable to get any doucment from google on this and dont have time to get any analysis done also.

Regards

 

[KlausST]

Hi,

1) don't expect much cost reduction. Rather ask the manufacturer than us. Only they can give you a reliable answer.
2) it may have: about none influence ... or destructive influence .... depending on your application.

Klaus

 

[Anonymous_Ricky]

Hi Klaus,

Thanks for reply

but any of your response was of no help.

 

[KlausST]

Hi,

Probably you are right.
But what answer do you expect?
1) Cost - and the save in cost - depends on volume, technology, country, materials, manufacturer...and so on.
2) Without knowing anything about your application... no one can say if there may arise a problem.
Currently you are the one with enough information to answer this. If you want us to give a good answer you need to provide useful informations about your application.

For sure you may complain that even this doesn't answer your questions.

*****
The other way round:
Let's assume one member gives these answers:
1) cost reduction is 3%
2) it will have no influence on your application.

My opinion on such answers is: Don't rely on them.
What happens when you later find out that one or both of these statements are wrong?

Klaus

 

[smijesh]

Well we will calculate the copper price and give to you

Suppose you have 4 layer of copper sheet (5cm x 5 cm)

When 1oz copper
Total copper weight : 0.00347cm(10z)*5cm*5cm*4layer* 8.92g/cm^3 = 3.09 grams
Copper price: 7.69$(Cu price per Kg) * 3.09grams/1000 = 0.023$
When 1/2oz copper
Copper price: 0.011$
Do you find any difference? We considered 100% copper track on the PCB !!!! if your track is very less on the PCB then the copper price will have much variation
Second questline is valid, reduce the thickness of grounds copper may lead to EMI

 

[Anonymous_Ricky]

Hi Klaus,

I got your point I should have been more specific with my application.

I am designing PCB for Automotives and it is not very high frequency <100MHz.

Thanks smijesh

 

[FvM]

The only reason to switch to 1/2 oz is to enable very fine PCB traces < 4 or 5 mils. Otherwise you are fine with 1 oz standard.

 

[marce]

Going to a thinner copper weight may add cost, it depends on what standard laminates a pcb manufacturer uses, if they buy predominately 1oz then that will be their cheapest option. As KlausST has said talk to your PCB manufacturer...