Study On The MSAP Fabrication Technology And Signal Integrity Of High-speed Printed Circuit

The application fields including 5G communication and Internet of Things require high-speed and high-integrity signal transmission,which poses new challenges to the existing Printed Circuit Board(PCB)manufacturing technology,and promotes the development of communication PCB toward low roughness,high-density interconnection and low insertion loss.At present,through the development of PCB manufacturing materials,improvement of manufacturing process and structure design to improve the high-frequency and high-speed performance of PCB is a hot research topic in the industry.Based on the technology of modified semi-additive process(mSAP),this paper studies the factors affecting the signal integrity of high frequency and high-speed PCB,such as the material,manufacturing process,and surface finishing of copper surface,and obtains the law of the interaction between the insertion loss and these mentioned factors.And applying it to production practice,and achieves better benefits.It includes the following contents:Four layers of high-frequency and high-speed PCB was fabricated with 3?m copper foil,M6 G high-speed material and 1035(RC70%)prepreg as structural materials.Aiming at the important factors affecting the signal integrity of high-frequency and high-speed PCB,such as surface roughness and etching factor,the high-frequency and high-speed PCB fabrication technology based on research materials and mSAP fabrication technology was explored.Self-made test PCB signal transmission loss was tested by vector network analyzer,in order to study the relationship between the key material and process of PCB manufacturing and its high frequency and high-speed signal transmission integrity.The results show that the etching factor of the mSAP technology can reach 3.43,and the signal interpolation loss of the test board is reduced by 33.071 dB/m at 20 GHz frequency compared with the products of the existing technology(subtraction method).It can be concluded that high-frequency and high-speed PCB based on mSAP technology has great advantages,and the performance and fabrication process of structural materials are the key factors.Based on the "skin effect" control of high frequency and high-speed line signal transmission,the copper surface modification technology for making high frequency and high-speed PCB special copper foil by mSAP fabrication technology and the relationship between the technological parameters of the technology and the transmission signal integrity of the self-made test board were studied.The surface characteristics and signal transmission losses of different copper surface modified circuits were tested by using 3D laser microscope and vector network analyzer.The results show that the signal insertion loss is the lowest after surface modification of electroless silver at the frequency of 20 GHz:-50.59 dB/m.Existing PCB theory shows that the PCB stack design has a direct impact on the signal integrity.Two kinds of high-frequency and high-speed PCB stacking structures are designed.The corresponding test boards were fabricated by the optimum technology of mSAP.The loss of signal transmission in electronic circuit and dielectric properties of substrate materials were tested and extracted by vector network analyzer and ADS software.The relationship between the stacking modes of high-speed materials,semicured sheets,the combination modes of dielectric parameters of materials and their integrity of the transmission signal.The results show that the change of dielectric constant(Dk)and dielectric loss factor(Df)of the substrate material is related to the type of fiberglass cloth and the glue content,and the signal insertion loss decreases with the decrease of Dk and Df values.