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Semiconductor Laser and Ceramic Substrate

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  What is a semiconductor laser?

  Semiconductor laser,also known as semiconductor laser diode(LD),refers to a kind of laser with semiconductor material as working material.The process of laser generation is very special.The commonly used materials are gallium arsenide(GaAs),cadmium sulfide(CDS),indium phosphide(INP),zinc sulfide(ZnS),etc.Ceramic substrate.There are three kinds of excitation modes:electric injection,electron beam excitation and optical pump.According to the structure classification,semiconductor laser devices can be divided into homojunction,single heterojunction,double heterojunction and so on.The three elements of semiconductor laser are gain equal to or greater than loss,resonator and laser radiation.

  Semiconductor laser has the advantages of small size,long life,easy integration,high photoelectric conversion power, is widely used in laser communication,laser display,laser drilling,laser cutting,laser welding,laser indication,laser printing,laser marking,laser indication,laser medical treatment,etc.

  Structure of semiconductor laser

  The simplest semiconductor laser consists of thin active layer,p-type and n-type confinement layer.The active layer is between p-type and n-type.The PN heterojunction is biased forward by ohmic contact,and the current is injected into a large area covering the whole laser chip.

  Taking GaAs laser as an example,the heat dissipation and point contact parts have certain requirements for the selection of materials.The ceramic substrate of ceramic circuit board has good thermal and electrical properties,and is an excellent material for power LED packaging,laser and UV.It is especially suitable for the packaging structure of multi chip packaging(MCM)and substrate direct bonding chip(COB).Together,it can also be used as other high power Power semiconductor module's heat dissipation circuit base plate,high current switch,relay,antenna,filter,solar energy inverter,etc.At present,the basic choice of GaAs laser is ceramic circuit board,and aluminum oxide and aluminum nitride ceramic circuit board are the most commonly used ceramic circuit board.

  Semiconductor laser packaging process

  The packaging process of semiconductor laser can be roughly divided into the following processes:cleaning,evaporation,eutectic patch,sintering,gold wire,ball welding,welding lead,visual inspection,pre-aging test,aging,post-aging test,capping,packaging and warehousing.

  1.The cleaning function mainly includes the cleaning of heat sink,pipe seat,ceramic chip and chip box,including the daily cleaning of some instruments,such as:all fiberglass ventilation cabinet,ultra pure water machine,oven,ultrasonic cleaning machine,etc.

  2.Evaporation is mainly used for heat sink evaporation of solder and ceramic plate evaporation of metal electrode.Soft solder requires small welding stress,mainly referring to heat sink materials with different thermal expansion coefficient and chip;hard solder requires large welding stress,good fatigue resistance and thermal conductivity,mainly referring to heat sink materials with different thermal expansion coefficient and chip.Heat sink requires high thermal conductivity,not easy to pollute,easy to process,easy to weld,thermal expansion coefficient and chip matching.

  3.The main function of eutectic patch or sintering is to realize the chip and socket or heat sink eutectic patch through the preformed solder strip,and the chip,to socket,solder strip,etc.are touched.

  4.The main function of gold wire ball welding is to connect LD chip,PD chip and ceramic metal or tube socket.

  5.The welding lead is mainly used to connect the C-mount socket lead.The process materials to be touched include electric soldering iron,copper lead,solder wire,flux,C-mount,etc.

  6.The main function of visual inspection is to carry out precise observation and measurement on the patch,bonding,sealing cap,etc.through the body microscope and metallographic microscope,so as to complete the analysis of the appearance abnormality of the defective products.

  7.Reliability test and analysis of the laser at different temperatures after being sealed by DC stabilized voltage power supply,chiller and aging table to meet the requirements of aging test.

  8.Ceramic substrate.After sealing and testing,if the requirements are met,the sealing machine can be used to seal the to pipe of different models.

Ceramic substrate

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