Integrated Printed Circuit Board Buried Ultra-thin Core Board Embedded Capacitance And Resistance Slurry Technology And The Technology Was Studied

In recent years, the technology of electronics products in communication,automobile and consumer field is developing rapidly. The printed circuit board alsoneeds to continuously upgrade its performance in order to meet the developing ofelectronics products with low power consumption, multi-function, high performanceand miniature size. Capacitor and resistor embedded into the printed circuit boards cangreatly enhance integration and decrease in size of electronic products. It also canimprove the signal transmission performance and the reliability of the electrical function.In this paper, we aimed at developing the technology and producing methods ofembedded capacitor printed circuit board by etching ultra-thin core material andembedded resistor printed circuit board by laminating conductive carbon paste resistorinto inner layers. The studies in reliability of the embedded capacitor, embedded resistorand the printed circuit board products were also carried out. And the main contents areas follows.In the study of embedded capacitor technology, the ultra-thin core was processedby the double-sided etching and one step lamination method to make embeddedcapacitor structure. On the basis of setting reasonable parameters of every process, atype of leading board with two wings was designed and used to solve the problem aboutthe ultra-thin core jam-up or fractured and the dielectric layer braked in DES process.The inner layer pattern design of the ultra-thin core was improved in the insulation slot,no copper and melt area to solve the problem about the dielectric layer shrinking inlamination process. And the sections of hole were observed by metallographicmicroscope and scanning electron microscope to ensure that the drilling and platingprocess were reliable.In the study of embedded resistor technology, orthogonal design experiment wasadopted to optimize the parameters for screen printing process. The optimizedparameters were as follow.Scraper angle:75±5°; the printing pressure:0.6±0.1MPa; scraper speed:1.5m/min. When the scraper speed reduced to1.0m/min, the coefficient of variation of thepaste carbon resistors’ square resistance was decreased to0.79%. The precision of theresistance value was improved. It was found that the distribution of circuit patterns willaffect the carbon paste resistance. On the one hand, the relationship between the resistorpattern size and resistance was determined by means of the fitted regression equation.On the other hand, under the influence of the patterns effects, the square resistancewould increase7.7%in average by means of the probability distribution analysis. Basedon the results, the size of graphic was compensated on the film. The accuracy of theresistance value was improved. Meanwhile, the relationships between curing degree andcuring temperature or curing degree and curing time of the carbon paste were alsostudied. The suitable parameters which were the curing temperature of170℃andcuring time of240min were selected in order to ensure the reliable application of thecarbon paste resistor in laminating process.In the reliability study of embedded capacitor and embedded resistor products, thewater absorption test, the humidity test, the high potential test, the reflow test and thethermal cycle test were carried out. Not only the embedded capacitors had high resistantto voltage and moisture, but also the printed circuit board products showed good heatresistance performance. After336hours of humidity test or6times of reflow test or300cycles of thermal cycle test, capacitance of embedded capacitor changes were less than5%. It showed that the product has great reliability even applied under extremely badconditions. The embedded resistor layers were able to withstand3times of reflow testwithout delaminating, cracking and other defects. After240hours of humidity test, thesquare resistance increased no more than5%. And after100cycles of thermal cycle test,the square resistance changed less than1%. The embedded resistor had high reliability.Based on the above study, the reliable printed circuit board products withembedded capacitor and embedded resistor were obtained in practical applications.