Research On The Manufacturing Process Of Directing Plating Ceramic Substrate With Self-alignment Structure

With the development of LED technology, the requirement of high power LED is more and more higher. The substrate is the primary heat dissipation path, which undertakes the most of heat dissipation task. The heat dissipation substrate materials include plastic, metal and ceramic. The ceramic material is becoming the important development direction of LED due to its high thermal conductivity, thermal matching with chip materials and stable chemical properties. This paper summarizing LED packaging substrate, optimizing the Directing Plating Ceramic(DPC) process, which uses the Al2O3 ceramic for substrate material.This paper focuses on the DPC manufacturing process, optimizing the parameters of some processes, testing and evaluating the results, proposing a novel substrate with selfalignment structure.The main contents are as follows:(1)Accomplishing the manufacturing process of DPC substrate. First, the rinse is necessary, then depositing Ti/Cu thin film by sputter, the following step is UV lithography and developing, afterwards thickening the copper layer by electroplating, after that depositing a layer of Au thin film, the last process is removing the redundant mental layer and the dry film by wet etching.(2)The influence of sputtering parameters on the surface morphology of titanium thin film and the bonding strength between the titanium thin film and the substrate was studied. When the substrate temperature is 350?, the sputtering power density is 5.42w/cm2, the air pressure in the sputtering cavity is 0.6Pa, the structure of titanium thin film is dense and homogeneous. The maximum bonding strength between the titanium thin film and the substrate is 15 MPa.(3)The influence of electroplating parameters on the copper layer was studied. When the speed of reciprocating motion of cathode is 24 times per minute, the flow of the circulation of the electroplate liquid is slow, the current density is 2ASD, the plated copper layer is smooth and compact. The result of cross cut test for bonding strength is qualified, and the copper layer isn't warped after thermal shock test, the result of the square resistance test is 0.089(?-cm/?). It turns out that the plated copper shows good electrical and mechanical performances.(4)Proposing a novel DPC heat substrate with self-alignment structure. Chip can align to the pad due to the surface tension of solder, which increases efficiency of mounting chips. When the area ratio between pad and chip is from 0.82 to 1.18, the area ratio between solder and chip is from0.8-1.2,the initial position error is below 500?m, the horizontal alignment error is below 15?m, and the angular deflection is below 0.5°.