Analysis on the Causes of No Copper in PTH

Different resin systems and material substrates, different resin systems, will lead to the effect of copper and copper when the activation of the difference between the significant difference. Especially some of the CEM composite substrate and high-frequency silver substrate specificity, in the chemical treatment of copper, the need to take some more special approach to deal with, if the normal chemical Shen copper sometimes difficult to achieve good results.

Substrate Pretreatment

Some of the substrate may absorb moisture and itself in the pressure into the substrate part of the resin curing bad, so that the drilling may be due to the strength of the resin itself is not enough to cause poor quality drilling, drilling or hole wall resin tearing serious, So it is necessary to carry out the necessary baking when opening material. In addition, some laminates after laminating may also appear pp semi-cured film substrate area of ​​the hardening of the tree branches, will directly affect the drilling and deodorization activated copper and so on.

Drilling conditions are poor, mainly as follows: the hole resin dust, hole wall rough, empty mouth glitches serious, hole glitches, inner copper foil nail head, glass fiber area tear section length uneven, etc., will cause chemical copper A certain quality hidden dangers.

Brush plate in addition to mechanical methods to deal with the surface of the substrate pollution and clear the hole burr / Phi front, the surface cleaning, in many cases, but also play a cleaning to remove dust in the hole role. In particular, it is even more important to treat double panels without removing the slag.

Another point to explain, we do not think that in addition to the glue residue can go out of the hole glue residue and dust, in fact, many cases, in addition to the residue process on the dust treatment effect is very limited, because the dust in the bath will form a small glue Group, so that the bath is difficult to deal with, the micelles adsorbed on the hole wall may form the hole within the tumor, there may be in the subsequent processing process from the hole wall shedding, which may also cause holes within the hole without copper, so more Layer and double-sided board, the necessary mechanical brush plate and high pressure cleaning is also necessary, especially facing the industry trends, small hole plate and high aspect ratio board more and more common conditions. And even sometimes ultrasonic cleaning to remove dust in the hole has become a trend.

Reasonable and appropriate addition to the residue process, can greatly increase the hole than the binding force and the reliability of the inner connection, but in addition to the glue process and the lack of coordination between the tank problems will bring some occasional problems. In addition to plastic residue, it may cause the hole in the glass fiber protruding, the hole rough, glass fiber cut-off point, the penetration of copper, the hole in the hole, the hole in the hole, , The separation of the inner layer of wedge-shaped hole between the inner layer of black copper caused by copper fracture or discontinuity or coating wrinkle coating stress increases and so on. In addition to a few pieces of glue between the coordination of control problems is also a very important reason.

Bulging / swollen enough, may cause the addition of rubber residue; bulky / swollen transition out of the more in addition to have been fluffy resin, then out of the sun when the copper will be activated bad copper is not on, even if the sink copper also There may be resin in the post-process subsidence, hole wall detachment and other defects; in addition to the tank in terms of the new slot and the high processing activity may also be some low degree of coupling of single-function resin bifunctional resin and some three-function resin Plastic phenomenon, leading to the hole wall glass fiber protruding, glass fiber is more difficult to activate and chemical copper bonding force between the resin and worse, copper after plating due to the extremely uneven substrate deposition, chemical copper stress will be doubled, Can be clearly seen after the copper wall of copper chemical wall of a piece of film from the hole wall off, resulting in follow-up hole without copper.

Hole no copper open circuit, the PCB industry is not unfamiliar, but how to control? Many colleagues have asked many times. Sliced ​​to do a lot, the problem can not be completely improved, always repeated, today is the process of production, and tomorrow that is the process of production. In fact, control is not difficult, but some people can not adhere to the supervision and prevention only, always headache, foot pain.

The following is my personal hole on the hole without copper open view and control methods. The reason for producing holes without copper is nothing more than:

  1. Drilling dust holes or holes.
  2. Shen copper when the syrup has bubbles, the hole did not sink on the copper.
  3. There is a line of ink in the hole, not on the protective layer, after etching hole without copper.
  4. After the copper or plate after the hole in the acid and alkali syrup is not clean, the parking time is too long, resulting in slow attack.
  5. Improper operation, stay in the micro-erosion process is too long.
  6. Punch board pressure is too large, (design punching too close from the conductive hole) neatly open the middle.
  7. Electroplating syrup (tin, nickel) poor penetration.

For the seven major holes in the cause of copper-free reasons to improve:

  1. To easily produce dust holes (such as 0.3mm below the hole with 0.3mm) to increase the high pressure washing and deaerating process.
  2. To improve the potency and shock effect.
  3. to change the printing screen and the film.
  4. Extend the washing time and specify how many hours to complete the graphics transfer.
  5. Set the timer. 6. Increase the explosion-proof hole. Reduce the board force.
  6. Regularly do the penetration test.


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