High Power RF Amplifiers Module Assembly - Issues to Consider, Design, Materials and Process
RF transistors can be found in several present day electronics including mobile radio and telecommunication applications,TV & radio broadcast,avionics,radar and defense communications as well as industrial,scientific,medical(ISM)and broadcast applications.The increasing demands for data anywhere/anytime(mobile internet)requires increased deployment of wireless communication infrastructure.This has pushed upwards across the supply chain(suppliers and customers alike).At the core are RF power amplifiers(PA)with a very costly design,hence important to get it right as rework may not be possible.The assembly of RF power transistors in PA modules is the back-bone of these applications.Such modules are usually generating high power(> 100 watts)with different package outlines and lead configuration.The high power demands excellent thermal management,else product performance and lifetime(reliability)are compromised.As a consequence,the transistors are often packaged in “chunky SOT outlines,with a ceramic/plastic body and a metal flange.Packaging such RF power modules(or PA)has historically been achieved with bolt down de vices,where only the leads of the components were soldered(more akin to manual assembly operations).A thermal compound was used underneath the transistor.High volume assembly is a basic capability(with automation a necessity)to meet industry demand.There are a variety of issues to consider module assembly since there are strong interplay between design,materials and process in order to achieve the desired performance(electrical,thermal,mechanical,and reliability).Due to thermal management requirement,the transistors are normally soldered directly onto the pallet(laminate bonded onto a heat sink)with the leads and SMDs on to the laminate on the pallet.Base on the SOT outline(i.e.gull wing),a cavity or pedestal is required in the pallet with a cut-out in the laminate.Each PA module will be different in i.e.size,weight,materials,number of transistors,board construction with no two modules the same.With such spectra of possibilities in the module design and permutations on assembly processes,the paper outlines and addresses the key issues to consider and approach to achieve robust PA modules assembly.It includes but not limited to substrates,solders,heat sinks,plating,board design and reflow soldering(assembly process flow).Key to achieving the robust assembly process is an iterative approach with feedback at each step in the process including a modeled reflow profiling.In addition,a novel use of Rth(thermal impedance)in combination to acoustic microscopy/x-rays to assess the quality of the soldered interface is presented.The solder volume is key to accommodate manufacturing tolerances and solder joint reliability.Additionally,the issues presented constitute a “toll-box for PA module assembly,including microwave pallet modules with matched input/output impedance.
Packaging RF power amplifier microwave pallets soldering pallets
Tennyson Nguty An Xiao Henk Thoonen
NXP Semiconductors Gerstweg 2,6534 AE Nijmegen,The Netherlands
国际会议
The 15th International Conference on Electronic Packaging Technology (ICEPT 2014) ) (第十五届电子封装技术国际会议)
成都
英文
1375-1380
2014-08-12（万方平台首次上网日期，不代表论文的发表时间）