Research On Key Technologies Of High Power Diode Laser Array Packaging

The high-power diode laser is a device of highly developing potential and research value in laser industry.It is widely used in many areas which are very important to national interest and people's livehood.As diode laser array(LDA)chip is the core assembly unit of high-power diode lasers,its packaging quality not only has great influence on the output characteristics,like power,wavelength,polarization property and beam quality,but also determines the reliability,especially the life time of diode lasers.Therefore,the packaging technology of LDA is the foundation of high-power diode lasers development and manufacturing.This dissertation aims to solve three key problems in LDA packaging,which are Smile effect,chip heat dissipation and chip bonding reliability by doing the research both on theory and experiment and has reached the following achievements:1.Put forward the Smile effect reduction technology by stress compensation method and keep Smile effect within 0.5?m stably.This technology is based on stress compensation theory.In order to reduce Smile effect,it provides the method that controll the bare bar curve before bonding to generate an external stress in the bar to compensate the packaging thermal stress.Curve direction and curve quantity reflect the bare bar's external stress.So the external stress can be quantified indirectly by measuring the bend of the bare bar.So that the steady relationship between external stress and Smile effect is built.It makes the steady Smile control and the increase of yield realize.Experiment results show that this Smile effect reduction technology has no influence on photoelectric characteristics of LDA device.2.Put forward the Smile effect measuring technology by stylet scanning technology.This technology use the curve of LDA chip's N side surface to represent the bend of LDA chip.By contacting and scanning the curve of N side surface with a precision stylet,the approximate result of Smile effect is obtained rapidly.For the measure Smile effect,the profile is accurate,and the error of value is within 1?m,besides,the actual value dose not exceed the measure value.The technology has merits of easy operating and short measurement time.It can be accomplished within 1 minute.What's more,there's no need to drive the LDA devices when test Smile effect and can be measured immediately after die bonding.Thus the technology can be integrated into mass packaging process of LDA to realize the real time online monitoring for Smile effect.Which ensures the stability of bonding process and improvement of packaging yield.3.Basing on laser 3D printing technology,design and develop a laser 3D printing microchannel cooler which is made from nickel based rare earth materials doping alloy.This reduces the Smile effect of LDA and improves the stability and lifetime of the device.By using the function of low coefficient of thermal expansion(CTE,11ppm/K)and high corrosion resistance of the novel alloy,the CTE mismatch level between cooler and LDA is reduced and the electrochemical corrosion of cooler is avoided.Laser 3D printing technology is employed to fabricate the monolithic cooler,which eliminates the danger of coolant leak.Through numerical simulation,the internal structure of microchannel cooler is optimized to make up the lacking of low thermal conductivity of the alloy.Finally a microchannel cooler with sufficient heat dissipation capability is obtained.The testing result indicates that the cooler can meet the heat dissipation requirement of LDA with no more than 120W/bar continuous output.Under the condition of 0.3L/min cooling water flow and 25? water temperature,the thermal resistance of the cooler reaches 0.4K/W for cooling the cw 80W/bar LDA.It is merely of 11.1% larger than the that of commercial oxygen-free copper microchannel cooler.The pressure drop is 0.5bar.The Smile effect is 0.8?m,which is a 46.7% decrease compared with commercial oxygen-free copper microchannel cooler.The power degradation of devices is less than 3% after a 1000 hours aging.4.By using control variate method,AuSn soldering parameters' effects on LDA characteristics are investigated.Effect rules that bonding temperature,temperature holding time and bonding pressure act on soldering layer quality,power,wavelength red shift and residual stress are obtained.Meanwhile,the AuSn soldering process profile is optimized.Under the condition of cooling temperature 25? and continuous working current 60 A,the conduction cooling Mini-bar laser adopting the soldering process profile has 58.7W output power,11.1nm wavelength red shift,less than 0.3?m Smile effect and void-free soldering layer.This Packaging result is in the leading position in existing reports.