Design And Realization Of Materials And Interconnection For Printed Circuit Board With High Heat Dissipation

High-quality printed circuit board(PCB) is an essential supporter for the high-power device to realize signal processing and transmission in high speed. The development of materials with high heat dissipation and the design of high-density interconnection are significantly interested for the manufacture of high-reliable PCB. However, traditional PCB materials and technologies are challenged since materials with high heat dissipation should simultaneously have agreement with good thermal stability, high thermal conductivity and low price whilst high-density interconnection should meet the requirement of uniform thickness and multiple-order interconnection between interlaminations. Thus, the researches on the design of novel materials and interconnecting structures play a significant role in enhancing the level of PCB technologies both for scientific significance and practical value.(1) The fiber-glass-epoxy-resin(FR4) laminate, the polypheylene-ether(PPE) laminate and the hydrocarbon-polymer(HC) laminate were investigated on thermal conductive property, thermal stability and thermal expansion property. The results indicated that HC laminate exhibited the best performance with thermal conductivity of 0.797 Wm-1K-1, thermal decomposition temperature of 350 °C and the coefficient of thermal expansion(CTE) of 72.7×10-6/°C. However, the cost of HC laminate was so high that it could not be widly used to manufacture low-price PCB. Meanwhile, the failure of solder bubbles for through-hole interconnection was analysised. The result revealed that under the environment of high temperature for lead-free soldering, the molten solder could be blowed out of the through hole by the permeating moisture inside irregular hole wall. Low-price dielectric materials should be developed and reliable interconnection should be designed for manufacturing high-quality PCB.(2) AlN particles were minished in size and absorbed by oligomeric silsesquioxane after ball milling. AlN particles with different concentrations were added into the polymeric matrix of polyarylene ether nitrile(PEN) to form composite systems. The dispersity of AlN particles in PEN matrix was evaluated while thermal conductivity, thermal stability, CTE, dielectric properties, electrical resistivity and mechanical performance were measured to investigate the effects of AlN particles in different fractions on the performance of composites. It was found that AlN particles with the absorption of oligomeric silsesquioxane at their surface could enhance the particle dispersity in PEN matrix. Surface modification for AlN particles could improve thermal conductivity of composites by the way of reducing thermal resistance between phase interfaces. Thermal conductivity of the composites exhibited an increasing trend as the concentration of AlN particles raised. Thermal conductivity of 42.3 vol%AlN/PEN reached up to 0.779 Wm-1K-1. The improved Russell’s model could effectively predict a trend for thermal conductivity of the composite systems. The thermal stability of the composites increased with the increment of AlN content and all composites exhibited final decomposition temperature of above 440 °C. When AlN content was too high, AlN particles in PEN matrix could generate sediment and agglomeration with increasing temperature, resulting in negative CTE reduction of AlN/PEN composite. An increase of the dielectric constant and the dielectric loss were observed in AlN/PEN composite with the increase in the fraction of AlN particles. A weak dependence on dielectric loss and dielectric loss was found in the composites when immediately increasing the frequency. Electrical resistivity of AlN/PEN composites decreased as the concentration of AlN particles increased but they still met the requirement of high electrical resistivity due to insulative PEN. 42.3 vol% AlN/PEN had electrical resistivity of up to 1.39 GΩ.cm. All AlN/PEN composites were in good agreement with break strength of above 22.6 N.(3) Basic copper carbonate was produced from the hydrothermal reaction of CuSO4·5H2O and NaHCO3 with polyethylene glycol as an additive. Copper oxide(CuO) was obtained through thermal decomposition of solid-state basic copper carbonate. CuO particles with high purity exhibited nearly spherical appearance with aggregated porous flakes and had a wide size distribution ranging from 100 nm to 100 μm. After ultrasonic treatment, CuO particles in ethyl alcohol(CuO-EA) showed completely discrete flakes whil those in diethyl ether(CuO-DE) generated the compacted flake agglomerates. Size distribution, sedimentation rate, ultraviolet-visible(UV-vis) absorption, X-ray diffraction(XRD) patterns, X-ray photoelectron spectroscopy(XPS), Raman spectra and dissolution rate were investigated to evaluate the effects of morphological variation for CuO particles. As a result, CuO-EA particles induced more remarkable influence on above characterization: CuO-EA showed the size distribution ranging from 60 nm to 10 μm and lower sedimentation rate; two absorption peaks at 220 nm and 390 nm were found in UV-vis absorption spectra for CuO-EA; XRD diffraction peaks for CuO-EA slightly shifted to high angle; CuO-EA particles led to higher XPS peak intensity and an increase of binding energy; CuO-EA particles induced higher Raman intensity; CuO-EA particles with high dissolution rate of about 7 s were used to keep stable concentration of cupric ions in order to generate fine copper deposits in a plating system with insoluble anode.(4) Electrochemical behaviors of the base electrolyte containing different additives were investigated by galvanostatic potential transient measurements(GM), cyclic voltammetry tests(CV) and potentiostatic measurements. Copper deposits on sputtering copper seed from physical vapor deposition(PVD) were examined by a scanning electron microscope and X-ray diffraction spectra. Cross sections of copper pillars and fine line patterns were observed by metallographic microscope. GM result revealed ethylene oxide-propylene oxide co-polymer(EO/PO) performed a further inhibition on copper deposition in the presence of 60 mg/L chloride ions as the increment of EO/PO concentration and the maximal inhibition on copper deposition was found when EO/PO concentration reached 20 mg/L. GM, CV and potentiostatic results indicated that copper deposition was accelerated by synergetic effects of additives in the base electrolyte containing 60 mg/L chloride ions, 20 mg/L EO/PO and 0.7 mg/L bis-(sodium sulfopropyl)-disul?de. Compared to rolled copper sheet, PVD copper layer with even deposit surface was recommended to form the uniformity of copper deposition through increasing the growing density of copper particles. Cathodic oscillatory was employed to form uniform distribution of copper deposits in thickness. Copper grain growth was preferentially(1 1 1) textured. Bottom-up copper pillars and fine line patterns with plating uniformity were fabricated when combining the electrolyte with above formula, PVD copper layer and cathodic oscillatory.(5) Two novel PCB interconnecting structures, including resin-filled stacked interconnection and additive stacked interconnection, were designed and realized Resin-filled stacked interconnection exhibited a smooth and compacted result of resin fill and an accurate counterpoint while additive stacked interconnection generated fine and uniform copper lines, homogeneous copper pillars in thickness and good flatness for an entire board. Thus, these two interconnecting structures could enhance the high-density level of PCB manufacture.