Short answer: Heavy copper (over 2 oz / 70 um) raises cutting force and heat at the wall, so lower the feed entering and exiting, increase peck depth, and keep the stack thin. A 6 oz board runs about 0.8 mm/rev feed and at least 140k RPM spindle with three or fewer panels; bit life climbs from about 850 holes (tungsten) to 2,100 (TiAlN) to 4,600 (diamond-coated) per 0.3 mm hole.
Number: Heavy copper >2 oz / 70 um raises cutting force and heat; lower feed in/out, increase peck; 6 oz feed is about 0.8 mm/rev (3 oz 1.2), spindle >=140k RPM (3 oz 120k), stack <=3 (3 oz 5). Bit life per 0.3 mm hole is about 850 (tungsten), 2,100 (TiAlN), 4,600 (diamond-coated), with burr 22/8/3 um. Formulas: RPM = (SFM x 1000)/(pi x D), Feed = chip_load x RPM x flutes (CSDN thick-copper, aimpcb, b2bwiki, fany-eda).
Boundary: These are example starting points from third-party process references, not YUESHAN commitments; the laminate and drill makers' guides govern the actual recipe. The entry/backup board stabilizes the thick stack but does not set RPM/feed.
Once copper gets heavy — past 2 oz — drilling stops behaving like standard FR4. The extra metal loads the bit, heats the wall and fights the exit.
Adjust the program for heavy copper
| Parameter | 6 oz | 3 oz (reference) |
|---|---|---|
| Feed | ~0.8 mm/rev | ~1.2 mm/rev |
| Spindle | >=140k RPM | ~120k RPM |
| Stack | <=3 panels | ~5 panels |
Lower the feed entering and exiting the copper, and increase peck depth to clear chips and heat.
The formulas
- RPM = (SFM x 1000) / (pi x D)
- Feed = chip_load x RPM x flutes
Bit-life ladder
| Coating | Holes per 0.3 mm | Burr |
|---|---|---|
| Tungsten (std) | ~850 | 22 um |
| TiAlN | ~2,100 | 8 um |
| Diamond-coated | ~4,600 | 3 um |
These are example ranges from third-party process references (CSDN, aimpcb, b2bwiki), not a YUESHAN quote — confirm against your laminate and drill maker. A flat, rigid backup supports the thick stack; see the high-speed spindle page.
