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Study Of The Capillary Pressure Of Flip-Chip Underfill With Hexagonal Solder Bump Arrangement

Posted on:2019-07-06Degree:MasterType:Thesis
Country:ChinaCandidate:J J FangFull Text:PDF
GTID:2348330548961488Subject:Mechanical Manufacturing and Automation
Abstract/Summary:PDF Full Text Request
Flip-chip technology is widely used in semiconductor industry,underfill process driven by capillary force can protect chips from thermal-mechanical fatigue and increase service life.Underfill is significantly affected by the capillary pressure,which is related to the gap 1between the chip and substrate,the diameter of solder bumps,pitch and solder bump arrangements.Compared to quadrilateral,hexagonal arrangement has higher I/O capacity and has more resistance to loads.Therefore,the study of capillary pressure of underfill in hexagonal arrangement has important engineering value.Based on the existing calculating method of the average capillary pressure in quadrilateral arrangement,the calculated model of the average capillary pressure in hexagonal arrangement was further studied.The main work and results are as following:(1)According to the structure characteristics of hexagonal arrangement,using the principle of force balance and the conservation of mass,the underfill process was analyzed by stages,the filling area and the contact line jump value were analyzed,the mathematical model for calculating the average capillary pressure in both large and small pitch situation were obtained.The effects of solder bump arrangement and flow direction on average capillary pressure were studied.(2)According to visualization requirement,flip-chip samples in hexagonal arrangement were designed and made.Substrates and chips were made of transparent SiO2,solder bumps were made of silicon.SiO2 and silicon were fabricated by SOG technology,then silicon were etched into solder bumps by photolithography technology.Removable substrate was adopted to be used repeatedly.(3)Auto dispensing machine,stereo microscope and high speed camera were used to build the experiment platform.Several underfill experiments were carried out,the results were compared to calculated results,the accuracy of the model was verified,the analytic model of the underfilling flow in flip-chip packaging process was improved.
Keywords/Search Tags:Flip chip, Underfill, Hexagon, Capillary pressure, Solder bump arrangement
PDF Full Text Request
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