Why a capability sheet matters before you request a quote
When a board pushes the edge of layer count, line width, or RF material, the brochure line “high precision PCB” tells you nothing. What you need is a capability sheet: a concrete list of what the factory can hold, lot after lot, without a custom engineering exception on every order.
This page lays out OPCBA’s standard production range across layers, traces, drilling, materials, and surface finishes. The numbers below are typical values from our production lines. Your final tolerances depend on stack-up, copper weight, and material, so confirm the exact limits with our engineering team before you release a design.
Layer count and board types
We build rigid boards from 1 to 70 layers, including high-layer-count backplanes, HDI, rigid-flex, and RF hybrids. Thick-copper boards run from 3 oz to 12 oz finished copper. Finished board thickness spans 0.13 mm to 60 mm, with thin substrates down to 0.05 mm for non-blind-buried builds.
For HDI, we support 1+N+1, 2+N+2, and 3+N+3 builds, including any-layer interconnect. Laser drilling reaches 0.10 mm, and mechanical drilling holds 0.10 mm at up to 0.60 mm board thickness. Blind and buried vias are built through stacked lamination cycles (up to three presses on one side).
Minimum trace and space
Outer-layer trace and space reach 3 mil (about 0.075 mm) on 18 um base copper, scaling with copper weight. Inner-layer geometry runs tighter because there is no etch-back from plating: 3 mil lines are achievable on 18 um base copper after compensation.
The table below shows how minimum width and space move with base copper. Use it as an early check on whether your design fits standard production or needs a controlled-impedance review.
| Base copper | Min outer line / space (mil) | Min inner line / space (mil) |
|---|---|---|
| 12-18 um | 3.0 / 3.0 | 3.0 / 3.0 |
| 35 um | 4.5 / 3.5 | 3.0 / 3.5 |
| 70 um | 6.0 / 5.0 | 4.0 / 4.0 |
| 105-140 um | 8.0-9.0 / 6.0-7.0 | 5.0-7.0 / 5.0-7.0 |
Materials we work with
Standard FR-4 covers most designs. For RF and high-speed work we process Rogers (RO4000, RO3000, RT5000 series), Taconic (TLX, TLY, RF, TLC series), Arlon (Diclad, Cuclad, Isoclad, AD, CLTE), and Wangling PTFE (F4B, F4BM, F4BK). For high-Tg and halogen-free builds we use Isola (370HR, FR408HR, I-Speed, 185HR) and Shengyi grades. Material mixing such as Rogers, Taconic, or Arlon laminated with FR-4 is supported for hybrid stacks.
Material choice drives impedance, loss, and thermal behavior. If your stack-up is not settled, send the target specs and our team will propose a buildable laminate plan rather than forcing your design onto a single sheet.
Surface finishes
We offer the common finishes for both standard and fine-pitch assembly: ENIG, OSP, immersion tin, immersion silver, hard gold, and lead-free HASL. Selective finishes are available, including ENIG plus OSP, ENIG plus gold finger, and immersion silver or tin plus gold finger. ENIG nickel thickness sits at 3-5 um with gold 0.025-0.10 um; hard gold reaches 0.15-1.3 um.
Impedance control
Controlled impedance is built into the stack-up, not corrected after etching. We hold +/-5 ohm for targets under 50 ohm and +/-10 percent for targets at or above 50 ohm, with tighter +/-5 percent available on review. Tolerances apply to coplanar, microstrip, and stripline structures across FR-4 and RF laminates.
Bring the target impedance, the reference layer, and the dielectric stack. We return a verified plan with trace geometry before panel release.
Thick copper, rigid-flex, and thermal builds
Thick copper from 3 oz to 12 oz supports power and thermal boards. Rigid-flex builds run 2 to 10 layers, with minimum line and space of 0.5 mm / 0.5 mm, minimum drilled hole 0.1 mm, and 288 C thermal shock (10 seconds, three cycles). These builds suit foldable interconnects in aerospace, medical, and industrial hardware.
All boards meet 94V-0 flammability. Process controls hold ion contamination at or below 1 ug/cm2 and copper peel strength at 7.8 N/cm, which matters for long-term reliability in humid or cyclic environments.
Testing and acceptance
Every board passes through in-process inspection at each stage, plus final electrical test. We use flying-probe and universal grid testers, and our lab runs impedance, copper thickness, metallography, and ion-contamination checks. Acceptance follows IPC-A-600 and IPC-6018 for RF boards; military-grade builds can be quoted to GJB326A on request.
Test limits worth noting: through-hole copper averages 25 um (minimum 20 um single point), blind and buried vias average 20 um (minimum 18 um), and insulation resistance reaches 100 MΩ at 250 V.
How to use this sheet
Treat the numbers above as the standard envelope, not a promise for every stack-up. If your design sits near a limit, or mixes thick copper, HDI, and RF material, send the files early. Our engineering team confirms what is buildable and where a small change buys yield and cost.
Start with a process review request or browse finished solution examples to see how these capabilities map onto real boards.
