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DPC ceramic substrate: future power LED will use it

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  With the continuous increase of LED chip input power,the large amount of heat generated by large heat dissipation power puts forward newer and higher requirements for LED packaging materials.In the LED heat dissipation channel,the package substrate is a key link connecting the internal and external heat dissipation channels,and has the functions of heat dissipation channels,circuit connections and physical support for the chip.For high-power LED products,the package substrate is required to have high electrical insulation,high thermal conductivity,and thermal expansion coefficient matching the chip.

  Resin-based packaging substrate:The support cost is high and it is difficult to promote.

  EMC and SMC have high requirements for compression molding equipment.The price of a compression molding production line is about 10 million yuan,which is difficult to promote on a large scale.

  In recent years,chip-type LED stents have generally adopted high-temperature modified engineering plastic materials,using PPA(polyphthalamide)resin as raw materials.By adding modified fillers to enhance some of the physical and chemical properties of PPA raw materials,PPA materials are more suitable for injection molding and chip mounting LED brackets.PPA plastic has low thermal conductivity and heat dissipation is mainly through the metal lead frame,so it is only suitable for low-power LED packaging.

  With the industry's emphasis on LED heat dissipation,two new thermosetting plastic materials,epoxy molding compound(EMC)and sheet molding compound(SMC),have been introduced into the SMD LED bracket.EMC is a powdery molding compound made of high-performance phenolic resin as curing agent,high thermal conductivity silicon powder as filler,and various additives.SMC is mainly composed of about 30%unsaturated resin,about 40%glass fiber,inorganic filler and other additives.The thermal curing temperature of these two thermosetting molding compounds is about 150°C.After modification,the thermal conductivity can reach 4W/(m·k)~7W/(m·k),which is much higher than PPA plastic.However,the disadvantage is that it is difficult to balance fluidity and thermal conductivity,and the hardness is too high during curing and molding,which is prone to cracks and burrs.EMC and SMC have long curing time,relatively low molding efficiency,and high requirements for molding equipment,molds and other supporting equipment.The price of a matching production line is around 10 million yuan,which is difficult to promote on a large scale.


DPC ceramic substrate


  Metal core printed circuit board:The manufacturing process is complicated and the actual application is few.

  The processing and manufacturing process of the aluminum substrate is complicated and the cost is high.The thermal expansion coefficient of aluminum is very different from the thermal expansion coefficient of chip material,and it is rarely used in practical applications.

  With the development of light-emitting diode packaging towards lightness and low cost,on-chip packaging technology has gradually emerged.At present,metal core printed circuit boards are mostly used for COB packaging substrates,and such substrates are mostly used for high-power LED packaging,and the price is between medium and high prices.

  The current common high-power LED heat dissipation substrates in production have extremely low thermal conductivity of the insulating layer,and due to the existence of the insulating layer,they cannot withstand high-temperature soldering,which limits the optimization of the package structure and is not conducive to LED heat dissipation.

  How to improve the thermal conductivity of the epoxy resin insulation layer has become a research hotspot of aluminum substrates.At present,a modified epoxy resin or epoxy glass cloth bonding sheet doped with high thermal conductivity inorganic fillers(such as ceramic powder)is used to bond copper foil,insulators and aluminum plates by hot pressing.At present,a"full-adhesive aluminum substrate"has been developed in the world,and the thermal resistance of the full-adhesive aluminum substrate can reach 0.05K/W.In addition,a Taiwan company recently developed a type of diamond carbon material DLC and applied it Insulation layer for high-brightness LED packaging aluminum substrate.DLC has many excellent material properties,such as high thermal conductivity,thermal uniformity and high material strength.Therefore,replacing the epoxy insulating layer of the traditional metal-based printed circuit board(MCPCB)with DLC is expected to greatly improve the thermal conductivity of MCPCB,but its actual application effect has yet to be tested by the market.

  The aluminum substrate with better performance is to directly form an insulating layer on the aluminum plate,and then print the circuit.The biggest advantage of this method is strong bonding force and high thermal conductivity,which is 2.1w/(m·k).However,the processing and manufacturing processes of such aluminum substrates are complicated and costly.In addition,the thermal expansion coefficient of metal aluminum is very different from that of chip materials,and thermal cycling of the device tends to generate greater stress,which may eventually lead to failure,so it is rarely used in practical applications.
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