In electroplating production practice, plating uniformity is an important indicator for testing the quality of the coating in PCB manufacturers. They are very strict of this.ALLPCB is a topspeed pcb manufacturer in China, specializing in high quality and cheap pcb prototype & production, pcb assembly and smt stencil services online.For production, the uniformity of copper plating on the board directly affects the fabrication and formation of subsequent fine lines, and the uniformity of copper plating in the holes plays an important role in the reliability of inter layer conduction.
With the increasing demand for high-density lines and small-aperture multi-layer boards, the requirements for uniformity of plating on the board surface and the holes are inevitably higher, and the improvement and improvement of plating uniformity have become an urgent problem to be solved. This paper summarizes the general ideas and methods to improve the uniformity of the coating on the surface and the hole, and illustrates it through application examples, in order to provide some reference and guiding significance for actual production.
When the through hole is plated, the edge and tip effect of the electric field itself make the power line at the hole dense, and the thickness of the copper plating is large. With the deepening of the hole, the current density is getting smaller and smaller, and the ohmic resistance of the plating solution is increased, the exchange of the plating solution in the hole is not smooth, and the copper plating thickness gradient from the orifice to the center of the hole is likely to occur. The coating in the hole is not uniform and the reliability is not up to standard. Especially when the aspect ratio is relatively large, the uneven thickness of copper plating in the hole is particularly obvious.
For the improvement of the uniformity of the coating in the hole, that is, to improve the deep plating ability of the hole, not only the plating itself, but also the drilling quality and the effect of sinking copper from the previous process, optimizing the drilling and copper immersion conditions, and ensuring the effect of sinking copper. Based on the improvement of plating uniformity within the hole.ALLPCB would test every board after electroplating production.In 24H lead time,testing is an vital process that ALLPCB attach importance to.
For the electroplating process, first select the copper plating additive with good deep plating capability, and the high acid low copper plating solution, which is the prerequisite for ensuring the microporous plating of the thick plate. Secondly, choose the lower current density (or different current). The combination of density and long-term operating conditions is also the most common practice in the industry. In addition, the selection of a suitable plating solution (such as jet flow) is also beneficial to the exchange of solutions in the pores and enhance the plating effect.