Nobody can deny that it is a good idea to get an indicating price at designing stage from your PCB factory, ideally if the offer is high, then your PCB hardware engineers can modify the design accordingly in order to fit into the budget (I.E revise PCB stack up, reduce some special technology, etc?)
However, as a PCB factory in China, we need to let our customer know, what are the factors that may result in price change--after Gerber is finally released to us.
1. Line width/line space
For most of China PCB factory, standard price matrix based on 4/4mil line space and line width. If in Gerber, we found the minimum line width and space is smaller than 4/4mil, which is 0.1016mm, the PCB price will go up accordingly.
Note the 4/4mil standard is based on 1/1oz copper finish, if thicker copper finish required, then the minimum line space and width will be increased. And if the track clearance is less than 3mil, it is over capability for most of PCB factories!
2. Drill size
The standard drill to quote is minimum 0.3mm, which means for drill dia. smaller than 0.3mm, price will increase. This is because for tiny drill, the drill speed and efficiency will reduce, while corresponding copper plating shall be harder than normal condition.
3. Drill quantity per m2
Standard drill quantity range is less than 80k/m2. If the board array is very dense, over our standard, the price shall going up.
4. Array design
While we got the Gerber file, we will check the distance from edge to circuit/drill, then we will design the array, including decide whether to use side band, stamp hole or V-cut.
The final panel size shall impact a little on the price level.
5. Test dot quantity
For order using a test fixture, we have a minimum charge of around CNY600.00, and for indicating price we will quote as minimum charge.
By checking real Gerber, if the test dot is above 1300 dots, we will charge extra cost on fixture making.
Above is the general factors that will result in price change in every PCB coming in, and there are some other factors result in different price, some even differ from original much!
1. Surface gold area
If the surface finishing required is ENIG, then we have a limitation that the gold area shall be less than 20% (combine TOP and BOT side). Unfortunately if the engineer think their board need to have gold area over 20%, we must increase the price.
2. Peelable mask area/carbon ink area
Similar to surface gold area rule, any design of peelable mask or carbon ink over a certain area percentage, will result in higher number in quotation sheet.
3. stack up design
For multilayer PCB, the actual stack up shall have a large impact in quotation.
Wow, I am sure, at this point, you would not like to continue to know more! Now you already have an idea why, as a serious China PCB factory we don't prefer quoting without actual design! (actually for PCB over 6 layers, no factories will give quote without Gerber, because it is far in accurate.）