A preface.

No copper in the hole is a functional problem of PCB. With the development of science and technology, PCB precision (aspect ratio) is required to be higher and higher, which not only brings trouble to PCB manufacturers (contradiction between cost and quality), but also leaves serious quality hidden trouble to downstream customers! Do simple analysis at this point below, hope to have enlightenment and help to relevant colleague!

2. Fishbone diagram analysis

Simple analysis of PCB hole copper and improvement methods

Classification and characteristics of copper – free holes

1. No copper in the PTH hole: the electrical layer of the surface copper plate is uniform and normal. The electrical layer of the plate in the hole is evenly distributed from the orifice to the fracture, and the fracture is covered by the electrical layer after the drawing.

Simple analysis of PCB hole copper and improvement methods

2. Plate electric copper thin hole without copper:

(1) The whole plate copper thin hole without copper — surface copper and hole copper plate electrical layer is very thin, after the graphic electrical pretreatment of micro etching hole in the middle of most of the plate copper is corroded, after the graphic electrical layer is encased;

(2) there is no copper in the thin hole of the copper plate in the hole — the electric layer of the copper plate is uniform and normal, and the electric layer of the plate in the hole is decreasing from the hole to the fracture, and the fracture is generally in the middle of the hole, and the copper layer is left at the fracture

The right side has good homogeneity and symmetry, and the post-graph fracture is covered by graph layer.

Simple analysis of PCB hole copper and improvement methods

3. Repair damaged holes:

(1) copper repair bad hole — the table copper plate electrical layer is uniform and normal, the hole copper plate electrical layer has no tapering trend, the fracture is irregular, may appear in the hole mouth may also appear in the middle of the hole, in the hole wall often appear rough convex and other bad, diagram electric after the fracture is covered by the diagram electric layer.

(2) corrosion maintenance of the hole, the table copper plate electrical layer is uniform and normal, the hole copper plate electrical layer has no taping trend, the fracture is irregular, may appear in the orifice may also appear in the middle of the hole, in the hole wall often appear rough convex and other bad, the fracture diagram electrical layer did not wrap the plate electrical layer.

Simple analysis of PCB hole copper and improvement methods

4. No copper plug hole: after graphic etching, there are obvious substances stuck in the hole, most of the hole wall is eroded, the graphic electrical layer at the fracture is not covered by the plate electrical layer.

Simple analysis of PCB hole copper and improvement methods

5. Figure electrical hole without copper: the electrical layer at the fracture is not wrapped in the plate electrical layer — figure electrical layer and plate electrical layer thickness is uniform, the fracture is broken; The graphic electrical layer shows a tapering trend until it disappears, and the plate electrical layer continues to extend for a distance beyond the graphic electrical layer and then disconnects.

Simple analysis of PCB hole copper and improvement methods

Simple analysis of PCB hole copper and improvement methods

Iv. Improvement Direction:

1. Operation (upper and lower boards, parameter setting, maintenance, abnormal handling);

2. Equipment (crane, feeder, heating pen, vibration, air pump, filtration cycle);

3. Materials (plate, potion);

4. Methods (parameters, procedures, processes and quality control);

5. Environment (variation caused by dirty, messy and miscellaneous).

6. Measurement (liquid medicine test, copper visual inspection).