Hole Wall Roughness
Hole Wall Roughness Testing Method
The irregularities generated on the hole wall by the drilling process are called "hole wall roughness".
- Hole wall roughness is measured after the plating.
- The hole wall is inspected after cross section and the depth of the concave portion is measured from the base line as shown in the figure below.
- When stack drilling has been used, all the PWB panels are measured.
- The maximum roughness points are measured around final hit hit counts.
 |
Cross-section
- The hole wall roughness values are higher in the 45 deg plane against the glass fiber. (A 90 deg. cross-section is gives smaller values)
- Hole wall roughness is measured on the full diameter point. (50% of the hole is ground back) It should be noted that the roughness varies according to the cross-sectioned point.
Reference
data (roughness_e.pdf, PAGE3, 350KB)
