Common Key Techniquesof HDI Printed Circuit Board Research And Application

Printed circuit board (PCB) is the foundation of all kinds of electronic products,itsmain function is to support electronic components and connect electrical signals. Withthe development of electronic technology, electronic products trend to be light、thin、short and small, High density interconnect (HDI) technology correspondingly emerged.As HDI boards towardmore density, some of key techniques in HDI required to beovercome. This paper mainly studied the common key techniques in the process of HDIboards, and the achievements were applied to industrial trial production of10layersecond-order HDI boards with variety of copper thickness. The mainly results weregiven as follows:1.The process of micro-blind via of HDI board. The process parameters of blindvia with100μm in diameter through CO2laser were optimized by simplex optimization.The experimental data showed that the optimum parameters were: pulse width13.8μs,laser energy14.8mJ, pulse shot2and mask2.2mm, and the resultingblind via wasgood enough for follow-up process with the roundness of99.32%and the ratio of upperto lower aperture of82.36%. The importance of factors from primary to secondary onroundness was as follow: pulse energy＞pulse width＞pulse shot＞Mask, and on theratio of upper to lower aperture was as follow: Mask pulse＞energy＞pulse width＞pulse shot. In generally, the optimized parameters were important references forindustrial production.2.The process of filling the micro-blind via. The insoluble material was selected asanode to study the relationship between current density and filling effect of themicro-blind via. The results showed that the blind hole filling rate was high and theplating time was very long while low current density wasapplied，which suggested thatthe production efficiency is not good.On the other hand, there was an empty hole intheblind via although the plating time was short while high current density was applied,which implied that quality of product is bad. To take advantages of both high and lowcurrent density on filling phase of micro-blind via, a combined process parameters wasput forward. Under the combined parameters(1.8A/dm215min+1.0A/dm230min+1.8A/dm215min), the filling rate of the micro-blind via was high (96.1%) and platingtime was short, which improve the production efficiency greatly.3.The process of ladder laminatesprinted circuit boards(LLPCBs).A simple and low cost process was put forward to produce LLPCBsin this paper.To prove thefeasibility of this idea, the effects of resist typeon quality of lines on HDI were studied,and the relations between line width and etching compensation of two laddercopper-clad laminates(15μm/30μm and15μm/45μm) were set up. Finally, the LLPCBswere successfully produced and an original intellectual property of HDI ladder circuitboard production technology was developed.4.Common key techniques used in trial production. The Common key techniqueswere applied to manufacture a10layer second-order HDI boards with variety of copperthicknessonindustrial production line of Bomin Electronics Company. Finally,the targetboards were got with percent of pass77.9%, which laid a foundation for industrialapplication.