Array and System Integration Technology of Gold Electrode NTC Chip Thermistor
After 40 years of development, NTC thermal gold electrodes chip / silver electrode chip encapsulation technology and structure has experienced four stages, as shown in figure 4 shows.
1, pin type (Lamp) NTC thermal gold electrodes chip/silver electrode wafer packaging
Pin type packaging is commonly used 3-5 mm encapsulation structure. General for current smaller (20-30 mA), low power (less than 0.1 W) NTC thermal gold electrodes chip/silver electrode wafer packaging. Mainly used for the instrument shows or instruction, large scale integrated may also be as a display screen. Its weakness is that encapsulation thermal resistance is bigger (generally higher than 100 K/W), short life.
2, surface assembly (patch) type (SMT-NTC thermal gold electrodes chip / silver electrode chip) package
Surface mount technology (SMT) is a kind of can directly encapsulation good device stick, welded to designated location in the PCB surface a packaging technology. Specific and character, it is with specific tools or equipment will chip pin in advance on the coating adhesive and solder paste on the welding plate graphics, and then directly mounted to drill hole not install PCB surface, after wave soldering or flow again after welding, make the device and circuit established between reliable mechanic and electric connection. SMT technology has high reliability, good high frequency characteristics, easy to be realized automation etc, and is the most popular electronics industry of a packaging technology and process.
3, board and chip loading (COB) NTC thermal gold electrodes chip/silver electrode wafer packaging
COB is Chip On Board (Board Chip straight outfit) English abbreviations, is a kind of through the adhesive or solder will NTC thermal gold electrodes Chip/silver electrode Chip Chip to direct and stickup PCB, again through the wire bonding realize Chip and PCB electric interconnection between the packaging technology. PCB board can be low cost FR-4 materials (glass fiber reinforced epoxy resin), also can be high conductivity of metal matrix or ceramic matrix composites (such as aluminum plate or the copper ceramic substrates, etc.). And the lead bonding can be used under the high temperature of the hot ultrasound bonding (golden ball welding) under normal temperature and the ultrasonic bonding (aluminum PiDao welding). Mainly used in high power COB technology more chip array NTC thermal gold electrodes chip/silver electrode wafer packaging, compared with SMT, it not only greatly improved packaging power density, and reduce the encapsulation thermal resistance (usually 6 to 12 W/m.K).
4, system encapsulation type (SiP) NTC thermal gold electrodes chip/silver electrode wafer packaging
SiP (System in Package) is in last few years in order to adapt to the development of portable and System requirements of miniaturization, in System Chip System on Chip (SOC) developed on the basis of a new type of packaging integrated way. To SiP-NTC thermal gold electrodes chip/silver electrode for chip, can not only in a package assembling more semiconductor thermal chip, still can all sorts of different types of devices (such as power, control circuit, optical microstructures, sensors, etc) integrated together, the forming of a more complex, complete system. Compared with other package structure, SiP has good compatibility process (ceiling of the existing electronic packaging materials and process), high level of integration, low cost, can provide more new functions, easy to block test, short development cycle, etc. According to the technical types, SiP can be divided into four kinds: chip cascade type, module type, MCM type and three-dimensional (3 D) encapsulation type.
At present, high brightness temperature sensing NTC gold electrodes chip/silver electrode device to replace incandescent lamp chip and high-pressure mercury lamp, must improve the flux, or can use of the flux. And the increase of the flux can improve the level of integration, by increasing current density, use large size chip measures of implementing. And these will increase the thermal NTC gold electrodes chip/silver electrode chip power density, such as heat dissipation bad, it will lead to a NTC thermal gold electrodes chip/silver electrode chip chip "high temperature, which directly influence the NTC thermal gold electrodes chip/silver electrode chip device performance (such as semiconductor thermal efficiency, reduce output optical happen redshift, reduced life spans, etc.). More array (chip is the highlights the flux of a gain the most feasible scheme, but NTC thermal gold electrodes chip/silver electrode array (chip density is limited by the price, the available space, electrical connections, especially cooling, etc. Because of the high density of the semiconductor thermal chip integrated, cooling the temperature of the substrate is very high, must use effective heat sink structure and appropriate packaging process. Commonly used heat sink into passive and active heat dissipation structure. Passive cooling generally choose the high side the coefficient of fin, through the fins and the natural convection between air heat dissipation to the environment. The scheme of simple structure, high reliability, but due to natural convection heat transfer coefficient is low, only suitable for power density is lower, integration is not high. For high-power NTC thermal gold electrodes chip/silver electrode wafer packaging, it must be the active cooling, such as fin + fan, heat pipe, liquid forced convection, micro channel cooling, phase change the cooling, etc.
In system integration, Taiwan's new light electric company USES system packaging technology (SiP), and through the fin + heat pipe way highly efficient cooling module collocation, developed a 72 W, 80 W high brightness white light NTC thermal gold electrodes chip/silver electrode chips light source, as shown in figure 5 (a). Because encapsulation thermal resistance low (4.38 ℃ / W), when the environment temperature 25 ℃, NTC thermal gold electrodes chip/silver electrode chip and temperature control in the 60 ℃, thus ensuring the NTC thermal gold electrodes chip/silver electrode chip service life and good semiconductor thermal performance. And huazhong university of science and technology, used the COB encapsulation and micro spray cooling technology initiative, encapsulation out 220 W and 1500 W of super power NTC thermal gold electrodes chip/silver electrode chip.
