PCB Fabrication Cost Drivers | PCB Fabrication in India
• Impedance adders
- +/-10% tolerance is considered standard
- +/-7% tolerance adds ~20% (~10% in Asia)
- +/-5% tolerance adds ~30%
- These values are dependent upon original line widths, whether or not the tight toleranced lines are on plated layers,
- Paying for the tightened impedance tolerance may be of no benefit if the proposed stack up and the material set is not robust
- Etching tolerances are independent of line widths and using wider lines improved tolerances can be obtained
- A 0.1 mil line width difference on a 3 mil 50 Ohm line equals 6%
- A 0.1 mil line width difference on a 5 mil 50 Ohm line equals 9%
• Soldermask
- Glossy or matte solder mask – No cost adder
- Different solder mask colors – 0-5% depending on quantity/region
– Use caution with black or white solder mask (capability and yield issues)
- LDI solder mask adder – 10-20% depending on panel quantity/region
- The cost adder for different solder masks is due to having to break down the set-up for one color to use another
- Silk-screening is a batch process and is set up for each particular work order/part number
- For customers that use different solder mask colors to identify RoHS or lead-free products in their manufacturing process, consider using a different silkscreen color instead as a more cost-effective option
• Via plugging
- No cost adders for any via plugging or button printing of vias 18 mils (0.457mm) or less using solder mask in North America
- For Asia, cost adders are BP=3-5%, VP=7%, full SM fill=8-10%
- Plugging of vias >18 mil (drilled) requires design review
- Tenting of vias is unreliable, as it is hoped that the solder mask, a very thin viscous liquid, will span holes and not collapse
- Tented holes will break, and can entrap solution, leading to corrosion of copper and premature failure
- The best approaches, in order of fabricator preference, are as follows:
- Leave the vias completely open from both sides
- Leave vias open during finishing and apply a tent to one side (“button print”)
- Plug them completely and then tent over with a solder mask (“via plug”)
• Finishing adders
- OSP, silver, tin, ENIG, and leaded HASL are no-cost adders for North
- For ASIA, HASL & OSP no-cost adders, Immun. Ag 2-3%, Immun. Sn 5-10% & ENIG 10-19%.
- ENEPIG adds 5% per manufacturing panel (subcontract is higher)
- Lead-free HASL adds 5% per manufacturing panel (subcontract is higher)
- Hard gold is priced per in2 area and the current market cost of gold
- Selective finishes are priced as per design review
• Miscellaneous adders
- Scoring – No cost adder
- Milling – 5-10% (at +/-5 mil tolerance)
- Counterbores and countersinks (non-plated) – No cost adder
- Counterbores and countersinks (plated) – 5-10%
- Edge plating – 5-10% (plus additional costs associated with reduced #up on the manufacturing panel)
- Back drill – ~5% per drill size
- Castellations (half holes on edge) – 5-15% depending on size/density
- Cavities – Avoid if possible! (Cost dependent on design)
PCB Fabrication in India:- Cerra Systems is the leading PCB Manufacturing and PCB Fabricator company in India. The company provides services of professional high-quality multilayer Rigid PCB, Flexible PCB, Rigid-Flex PCB, Metal Core, and PTFE Teflon Printed Circuit Boards (PCB) for Avionics & defence (AS9100D, MIL-PRF, LCSO), Medical (ISO 13485), Automotive (IATF 16949) Instrumentation, and commercial applications.
For more details, visit us:- http://cerrasystems.com/hdi-pcb-microvias-india/
