CN102503382A - Al2O3 ceramic material for LED radiating substrate - Google Patents

Abstract

The invention discloses an Al2O3 ceramic material for an LED radiating substrate for overcoming the defects of over high sintering temperature, low thermal conductivity and excessive production cost of the current material. The ceramic material of the invention comprises the following ingredients in mass percent: 85-95% of Al2O3, 1-3% of CaO, 1-3% of MgO, 0.5-2% of BaO, 2-7% of SiO2 and 0.5-1% of ZrO. According to the invention, CaO-MgO-SiO2-BaO-ZrO2 glass is used as sintering accessory agent of Al2O3 ceramic, so that dense Al2O3 ceramic can be sintered at a low temperature of 1350-1500 DEG C, which greatly reduces the energy consumption and the production cost, and the rate of finished products is as high as 95%. The density of the prepared Al2O3 ceramic ranges from 3.45 to 3.75 g/cm3, the thermoconductivity ranges from 15 to 18 W/(m.K), and the volume resistivity thereof is larger than 1013 ohm.cm, so the Al2O3 ceramic can be used as LED radiating substrates.

Description

The LED heat-radiating substrate is used Al 2O 3Stupalith

Technical field

The present invention relates to the LED heat-radiating substrate with the field of materials technology, refer in particular to a kind of LED heat-radiating substrate and use Al ₂O ₃Stupalith.

Background technology

LED is the abbreviation of photodiode (Light Emitting Diode), is a kind of solid-state semiconducter device that can electric energy be converted into visible light, in field broad market prospect such as illumination and backlights.

In recent years; Raising along with perfect, the optical throughput and the light extraction efficiency of semiconductor material and packaging process; Power-type LED is applied in special lighting fields such as urban look, traffic sign, LCD backlight, automotive lighting, billboards, and strides forward to general lighting market.Yet along with improving constantly of led chip power input, big thermal value that big wasted power is brought and demanding light extraction efficiency have proposed renewal, higher requirement for the heat-radiating substrate material of LED.To the high-capacity LED product, its heat-radiating substrate material requirements has high electric insulation property, high stability, high thermal conductivity and and chip matched coefficient of thermal expansion (CTE), planarization and higher intensity.

The most frequently used traditionally LED of work heat-radiating substrate FR4 tellite (PCB) and metal-core printed circuit board (MCPCB) arranged.The thermal conductivity of pcb board about 0.36W/ (mK), thermal expansivity about 13～17ppm/K.Its advantage is that technology is ripe relatively, and with low cost, shortcoming is that thermal property is relatively poor, generally can only be applied to traditional low power LED.The MCPCB plate is that the metal (like aluminium, copper) that thermal conductivity coefficient is high is relatively put in the pcb board, comes the enhance heat effect with this.But the insulation layer thermal conductivity is extremely low in the MCPCB plate, so insulation layer becomes the heat radiation bottleneck of this structure substrate, influences the radiating effect of whole base plate, makes that whole thermal conductivity also only is 1～2.2 W/ (mK); Owing to the existence of insulation layer, make it can't bear high-temperature soldering, thereby influenced the enforcement of packaging process simultaneously, limited the optimization of encapsulating structure, therefore be unfavorable for the LED heat radiation.

High-purity Al ₂O ₃Thermal conductivity under the pottery room temperature is 29W/ (mK), and is approaching with the thermal conductivity of iron and steel, and has high insulating property, the linear expansivity close with components and parts, high plurality of advantages such as chemicalstability; In addition, compare Al with the preparation of MCPCB ₂O ₃It is a lot of easily that the preparation of ceramic substrate is also wanted.Therefore, adopt Al ₂O ₃Stupalith substitutes traditional P CB and the MCPCB plate is the development trend of whole industry, Al ₂O ₃Stupalith has wide application prospect in power-type LED heat-radiating substrate field.

Yet, because Al ₂O ₂Self cationic charge is many, and radius is little, and the characteristics that ionic linkage is strong cause its lattice energy bigger, and spread coefficient is lower, and sintering temperature is high.The sintering temperature of general pure alumina pottery is about 1800 degree, and high like this sintering temperature generally realizes than difficulty in industry, is unfavorable for energy efficient; And the work-ing life of kiln and kiln furnitures is short, and the production cycle is long, and production efficiency is low; Also can there be more defective on the ceramic structure, unfavorable to material mechanical performance.This makes Al ₂O ₃Application and the popularization of pottery in LED heat-radiating substrate field receives very big restriction.

At present both at home and abroad the scientific worker be raw material with the high-purity superfine alumina powder or adopt advanced sintering process, with TiO ₂, Cr ₂O ₃, Fe ₂O ₃, MnO ₂Deng the oxide compound that appraises at the current rate is that sintering aid obtains the aluminum oxide powder pottery that sintering temperature is low, crystal grain is tiny.But starting material and equipment cost are too high, and production capacity is low, make production cost still higher; And can not obtain the alumina-ceramic of white when making sintering aid, thereby its range of application and little with the oxide compound that appraises at the current rate.In addition, although domestic successful is developed the low temperature co-fired Al that sintering temperature is lower than 1000 ℃ ₂O ₃Stupalith is also realized industrialization; But in order to reduce sintering temperature; Added up to the bad glass ingredient of the heat conductivility of 30wt%～40wt%, made the thermal conductivity of this type stupalith have only 2～3W/ (mK), can not satisfy the heat radiation requirement of great power LED device.

Therefore, develop the Al that has high thermal conductivity and lower sintering temperature simultaneously ₂O ₃Stupalith will greatly promote its application and popularization in LED heat-radiating substrate field.

Summary of the invention

To the deficiency of prior art, the invention provides a kind of LED heat-radiating substrate and use Al ₂O ₃Stupalith overcomes existing Al ₂O ₃The defective that the stupalith sintering temperature is high, thermal conductivity is low and production cost is excessive.

The solution that the present invention adopts is:

A kind of LED heat-radiating substrate is used Al ₂O ₃Stupalith by mass percentage, comprises following component:

Al ₂O ₃ 85～95%

CaO 1～3%

MgO 1～3%

BaO 0.5～2%

SiO ₂ 2～7%

ZrO ₂ 0.5～1%。

Wherein, A1 ₂O ₃Content the sintering temperature and the thermal conductivity of this material had considerable influence, A1 ₂O ₃Content is higher, and then sintering temperature is higher, and thermal conductivity is bigger; Otherwise then sintering temperature is lower, and thermal conductivity is also little.

Yet, owing to this CaO, BaO, SiO ₂Ability and A1 in sintering process ₂O ₃Generate low-melting calcium barium glass, play the effect that reduces sintering temperature.Therefore, an amount of adding can significantly reduce the sintering temperature of porcelain body, increases the density of porcelain body.But because this type glass heat conductivility is not good, too high like add-on, the thermal conductivity of porcelain body be will obviously reduce, and pore and tiny crack in porcelain body, produced easily, reduce the density of porcelain body.In addition, through changing CaO, BaO, SiO in the glass ingredient ₂The content ratio, can adjust fusing point, thermal expansivity and the wellability of glassy phase, make it satisfy different content A1 ₂O ₃The processing requirement of pottery.

Simultaneously, because MgO ability and A1 ₂O ₃Generate magnesium-aluminium spinel, improved the crystal boundary bonding force, so the content of MgO is to A1 ₂O ₃The density influence of pottery is very big.An amount of interpolation of MgO can make porcelain body obtain thin brilliant microtexture, increases the density of pottery.This is because MgO and A1 ₂O ₃At high temperature solid state reaction can take place, on crystal boundary, form the spinel phase, hindered A1 ₂O ₃Growing up of crystal grain, at this moment MgO is A1 ₂O ₃Microstructure stablizer in the sintering process.And the excessive interpolation of MgO, make its very easily with A1 ₂O ₃Reaction forms second phase, and the effect of densification is obviously weakened.

And, an amount of ZrO ₂Add the viscosity that helps reducing fused glassy phase under the high temperature, help the uniform distribution of glassy phase, promoted sintering along ceramic grain-boundary.But work as ZrO ₂Adding when too much, the sintering temperature of pottery will increase.

The present invention adopts CaO-MgO-SiO ₂-BaO-ZrO ₂Be that low melting glass is as Al ₂O ₃The sintering aid of pottery has not only solved existing Al ₂O ₃The defective that the stupalith sintering temperature is too high can be reduced to 1350 ℃～1500 ℃ with sintering temperature, has obviously reduced energy consumption and production cost, and the finished product rate can reach 95% simultaneously; And make the application's Al ₂O ₃Stupalith keeps higher heat-conduction coefficient, has high thermal conductivity and lower sintering temperature simultaneously.Its sintering temperature is between 1350～1500 ℃, and thermal conductivity is between 15～18W/ (mK), and porcelain body density is between 3.45～3.75g/cm ³Between, volume specific resistance is greater than 10 ¹³Ω cm.This kind stupalith especially can be used as the heat-radiating substrate of great power LED device, has good market outlook and commercial value.

Embodiment

Percentages of ingredients among the following embodiment (%) unless otherwise indicated, means mass percent.

Embodiment 1:

By component: Al ₂O ₃: 95%, CaO:1%, MgO:1%, BaO:0.5%, SiO ₂: 2%, ZrO ₂: 0.5% carries out proportioning, through 1500 ℃ of temperature sintering, can make Al ₂O ₃Stupalith, its yield rate reaches 96%.Through test, obtained Al ₂O ₃The thermal conductivity of stupalith is 18W/ (mK), porcelain body density 3.75g/cm ³, volume specific resistance is greater than 10 ¹³Ω cm.

Embodiment 2:

By component: Al ₂O ₃: 90%, CaO:2%, MgO:1.5%, BaO:1.0%, SiO ₂: 4.8%, ZrO ₂: 0.7% carries out proportioning, through 1450 ℃ of temperature sintering, can make Al ₂O ₃Stupalith, its yield rate reaches 95%.Through test, obtained Al ₂O ₃The thermal conductivity of stupalith is 17W/ (mK), porcelain body density 3.70g/cm ³, volume specific resistance is greater than 10 ¹⁴Ω cm.

Embodiment 3:

By component: Al ₂O ₃: 89%, CaO:3%, MgO:0.8%, BaO:1.1%, SiO ₂: 5.5%, ZrO ₂: 0.6% carries out proportioning, through 1400 ℃ of temperature sintering, can make Al ₂O ₃Stupalith, its yield rate reaches 95.5%.Through test, obtained Al ₂O ₃The thermal conductivity of stupalith is 16W/ (mK), porcelain body density 3.60g/cm ³, volume specific resistance is greater than 10 ¹⁴Ω cm.

Embodiment 4:

By component: Al ₂O ₃: 85%, CaO:2%, MgO:3%, BaO:2%, SiO ₂: 7%, ZrO ₂: 1% carries out proportioning, through 1350 ℃ of temperature sintering, can make Al ₂O ₃Stupalith, its yield rate reaches 97%.Through test, obtained Al ₂O ₃The thermal conductivity of stupalith is 15W/ (mK), porcelain body density 3.45g/cm ³, volume specific resistance is greater than 10 ¹⁵Ω cm.

Claims (1)

1. a LED heat-radiating substrate is used Al ₂O ₃Stupalith is characterized in that: by mass percentage, comprise following component:

Al ₂O ₃ 85～95%

CaO 1～3%

MgO 1～3%

BaO 0.5～2%

SiO ₂ 2～7%

ZrO ₂ 0.5～1%。