Main Features: When the length of panel plating is symmetrical, the pattern plating covers the panel plating, and the corner of the pattern plating doesn’t obviously become thinner and has a curved shape while no wicking is found, it can be judged as PTH air bubbles voids.
Cause analysis:
A.Abnormality in vibrating motor (insufficient vibration).
B.Abnormality in the basket (serious breaks in the basket), or no fix between the son basket and mother basket
C.Abnormality in the rack (there’s no hook behind the rack to combine with the basket, which causes a bigger amplitude of fluctuations during the vibrating process, invisibly reducing the amplitude of the vibration in the board and thus failing to remove air bubbles).
D.Lay up during the PTH production process (the boards are rather thin and not used along with the specialized thin board frame, so lay up occurs due to fluctuation, vibration and air agitation, which further impacts the penetration ability and the bubble breaking ability of the solution ).
E.Insufficient fluctuation or under inflation.
F.High aspect ratio that leads to poor throwing power.
Improvement measures:
A.One should check if the vibrating motor operates normally before the production, and regularly perform fluctuation tests on it. The general fluctuation is controlled at 0.2 mm–0.4 mm. (Note: For boards with a high aspect ratio, to ensure its good throwing power, the fluctuation has to be controlled at the upper limit. But at this time, whether the basket can take it must be taken into account).
B.One should check the basket for the production to avoid the hitch point of the rack from breaking and further failing to achieve the “vibration” effect. It is suggested that 2–3 baskets be additionally prepared as backups.
C.Boards with a thickness of ≤ 0.8 mm should be used with the specialized thin board frame; if there’s no specialized thin board frame, ordinary racks can be used by being inserting boards alternately, leaving a free space in between. However, during the production process, the activity of the electroless copper plating tank must be taken into account, and whether the area of the production board is enough
D.Install ultrasound device for the activating and conditioning.
E.Check if the fluctuation device, inflation device, vibration and pneumatic are normal.
F.For boards with a high aspect ratio (boards too thick with small hole diameters), one can use racks for PTH by inserting them alternately (i.e., leaving a free space in between). However, whether the loading capacity is enough and whether the activity of the electroless copper plating tank is sufficient should be considered.
G.Install pneumatic devices in the three tanks: conditioning tank, activating tank and electroless copper plating tank.
H.Consider if horizontal electroplating can be adopted.
