The substrate pretreatment problem
Some substrates may absorb moisture, and
some resins may be poorly cured when pressed into the substrate, so the
strength of the hole is poor due to insufficient strength of the resin itself,
and the drilling may be severe or the resin wall of the hole may be torn.
Therefore, it must be baked when the material is opened. In addition, some
laminates may also have poor curing conditions in the substrate of the pp
prepreg, which will directly affect the drilling and degumming activation of
the copper sink.
The drilling conditions are too poor, mainly as follows: the resin dust in the
hole is too large, the hole wall is rough, the pores are serious, the burrs in
the hole, the inner copper foil nail head, the length tearing the fiberglass
area, etc., will cause certain chemical copper. Quality hazard.
In addition to mechanically treating the surface contamination of the substrate
and removing burrs/surfaces of the holes, the brushed surface is also cleaned
and, in many cases, used to clean and remove dust from the holes. In
particular, it is more important to handle double panels without
decontamination.
Reasonable and proper removal of the slag process can greatly improve the hole
specific bond force and the reliability of the inner layer connection, but the
problem of poor coordination between the glue removal process and the related
bath liquid brings some accidental problems. Insufficient slag will cause
micropores in the pore walls, poor adhesion of the inner layer, detachment of
the pore walls, blowholes and other quality hazards; excessive glue removal may
also cause the glass fibers in the pores to protrude, the pores are rough, the
fiber cross-section points, and the copper penetrates into the wedge shape. The
inner layer of the pores ruptures between the inner layers of the black copper
causing the copper to be broken or discontinuous or the plating stress of the
coating to increase.
The reason for creating a hole without copper is simply:
1. Drill out the dust plug hole or hole.
2. Electroplating syrup (tin, nickel) has poor permeability.
3. Improper operation, the residence time is too long during the micro-etching
process.
4. After the copper is frozen or cleaned, the acid-base syrup in the hole is
not cleaned, and the parking time is too long, resulting in slow bite.
5. The pressure of the punching plate is too large, and the design punch is too
close to the conductive hole.
6. When the copper is frozen, there are bubbles in the syrup and the holes are
not covered by copper.
7. Wired ink in the hole, no protective layer is applied, and there is no
copper in the hole after etching.
