Multilayer PCB circuit board rapid prototyping these difficulties you have encountered?

In the process of multilayer PCB circuit board rapid prototyping often encounter some more difficult problems, what are these difficulties? I believe that many partners have experienced, take a look at it!

Difficulty 1: inter-layer alignment

Due to the rapid development of electronic equipment, the demand for PCB has become more and more sophisticated, more and more electronic products need to use multi-layer PCB. based on the multilayer PCB circuit boards in a large number of layers, the user of PCB layer alignment requirements are becoming higher and higher.

Generally the alignment tolerance between PCB layers is controlled at 75 microns. However,2 oz copper thickness in mm due to the multilayer PCB circuit board unit size, graphics conversion workshop environment temperature and humidity, different core board inconsistency caused by the bit error overlap, the interlayer positioning method and other factors, resulting in multilayer PCB circuit board layer alignment control is more difficult.

Difficulty 2: internal circuit production

Multilayer PCB circuit boards use high TG, high-speed, high-frequency, thick copper, thin dielectric layer and other materials, the internal circuit production and graphic size control has put forward high requirements. For example, the integrity of impedance signal transmission increases the difficulty of internal circuit fabrication.

In the PCB circuit board rapid prototyping process, the width and line spacing is small, open and short-circuit increase, low pass rate; fine line signal layer, the inner layer of AOI leakage detection probability increases; thin inner core board, easy to wrinkle,plated through hole vs via poor exposure, etching machine when easy to curl; high-level plate is mostly a system board, the size of the unit size is larger, and the product end-of-life cost is higher.

Difficulty 3: compression manufacturing

In the PCB circuit board rapid prototyping process, many inner core boards and semi-cured boards are stacked, in the stamping production is prone to slippery boards, delamination, resin voids and bubble residue and other defects. In the design of the laminated structure, full consideration should be given to the material's heat resistance, pressure resistance, glue content and dielectric thickness, to develop an effective multi-layer circuit board material pressing program. Due to the large number of layers of PCB circuit boards, expansion and contraction control and size coefficient compensation can not maintain consistency, and the thin interlayer insulation layer can easily lead to interlayer reliability test failure.

Difficulty four: drilling production

In the PCB circuit board rapid prototyping process, a part of the board increases the difficulty of drilling roughness, drilling burrs and de-drilling dirt. Due to the number of layers, the cumulative total copper thickness and board thickness, drilling is easy to break the knife; dense BGA more than narrow hole wall spacing caused by CAF failure problems; due to the thickness of the board is easy to lead to the phenomenon of oblique drilling.

I believe many people have encountered these difficulties, but there are always more solutions than problems. As long as you grasp the core of the problem, you can quickly solve it.