The normal lnner copper layers are drawn out or extruded by the drill to create a form like a nail head shape.
Small nail heading
Big nail heading
| Cause | Failure condition | Countermeasure |
|---|---|---|
| ST Type | Increased contact area with the hole wall expands copper edges. | UC type |
| Large margin width | Increased area of contact between the drill bit surface and hole wall raises drilling temperature. | Setting correct margin length. |
| Cause | Failure condition | Countermeasure |
|---|---|---|
| Repointed drill bit which has excessive diameter wearing at the drill tip. | Higher drilling temperature can cause the copper layers to expand. | Check wearing condition. Repointing must remove correct amount to return full diameter. |
| Cause | Failure condition | Countermeasure |
|---|---|---|
| Low chipload and hit count to high | Higher drilling temperature can cause nail heading of the copper inner layers. | Higher chipload |
| Cause | Failure condition | Countermeasure |
|---|---|---|
| Hinge number and thickness of PCB copper layers | Increased cutting resistance raises the drilling temperature, causing smear. | Decrease PCB stack heights and hit count to reduce drill bit damage. Use double drilling method. |
| Cause | Failure condition | Countermeasure |
|---|---|---|
| TIR (Total Indicated Runout) | Large dynamic deflection worsens accuracy, and causes breakage. | Control spindle run out (maintenance and repair). Recommended value <10 micron (<5 micron is better for <0.3mm drill bits) |
| Poor drill chucking (Dust in spindle chuck, spindle chuck wearing, scratching, marking for identification, etc.) | Increased dynamic deflection by poor chucking causes breakage. | Maintain collet chuck. |
| Uneven contact of bush with entry board | Uneven bush contact, a damaged bush or poor surface condition of the bush contact area causes breakage. | Check whether pressure foot is parallel with the machine table. Check bush contact using PV-Checker. (Recommendation: Over 80% surface touching bush) |
PRODUCT 01 PCB Drills / Routers / Ultra precision micro-hole drill
