Masao Segawa

Lead free die mount adhesive using silver nanoparticles applied to power discrete package

Lead-free materials are required to replace conventional lead-containing solder for environmental protection. The Pb-rich solder die mount material in a high-power transistor package is required to be replaced by a silver adhesive paste. The silver paste has disadvantages such as low thermal conductivity and high electrical resistivity, since conduction paths are achieved only by mechanical contacts between silver particles. Recently, a new conductive paste containing silver particles and silver nanoparticles with a particle size of 3–7 nm in diameter was developed. The paste shows very low electrical resistivity of 6×10−6 ohm.cm, since the silver nanoparticles can be fused at temperatures below 200°C. We have been studying the possibility of the paste as a die mount material for high-power transistor packages. It was confirmed that the paste had a very high thermal conductivity of 51 W/mK. We fabricated a high-power transistor package using this paste. As a result, the package showed lower thermal resist...

A micro miniaturized CCD color camera utilizing a newly developed CCD packaging technique

A small camera using a CCD (charge coupled device) image sensor has been widely used in various fields. The authors have developed the worlds smallest and highest picture quality CCD color camera to enlarge the camera market. This camera is 7.0 mm in diameter, 47 mm in length, and only 4 g in weight. The driving force to realize the camera was to develop the smallest CCD package. The new CCD package, TOG:TAB (tape automated bonding) on glass, is almost as small as a CCD bare chip with a 1/4-inch size. Furthermore, the TOG package realizes a simple production process and high reliability. >

Flip chip interconnection method applied to small camera module

Small cameras used as image storage devices have been rapidly applied to mobile information devices since the improvement of picture quality and the development of an easy picture processing method. The authors have developed a small camera module (3.6 cc, 30(W)/spl times/15(D)/spl times/8(H) mm/sup 3/; including lens unit) using two bare chip bonding methods. One is the CMOS image sensor packaging technique for fabrication on a flexible substrate by the ACP (anisotropic conductive paste) bonding method. The other is the flip chip bonding method which utilizes the advanced ACP method for a DSP (digital signal processor) chip. The new ACP enables a short resin curing time of less than six seconds. The ACP can also withstand the reflow soldering process, so that the bare chip IC and chip components can be mounted on the same substrate. By using these bare chip bonding techniques, the small camera module was realized. Regarding the ACP, its humidity absorption property was improved to obtain a high reliability. The filler content of the ACP was also controlled to obtain a high reliability. The flip chip bonding margin was confirmed to be applicable to mass production.

A CMOS image sensor module applied for a digital still camera utilizing the TAB on glass (TOG) bonding method

The worlds smallest (105/spl times/55/spl times/20 mm) and lightest (130 g) digital still camera has been developed, in which a 330 K pixel complementary metal-oxide-semiconductor (CMOS) image sensor chip is used as an image sensor. The authors have developed a new thinner and smaller image sensor module, called tape automated bonding (TAB) on glass (TOG) module, using the anisotropic conductive paste (ACP) interconnection method. The TOG production process was established by obtaining optimum bonding conditions for both optical glass bonding and CMOS chip bonding to the TAB tape. The bonding conditions including sufficient bonding margins, were mainly studied. The TOG module obtained good imaging properties, It also has a high reliability such as thermal cycle test (-40 to +110/spl deg/C/30 min, 2000 cycles) and the high temperature storage test (60/spl deg/C, 90% RH, 3000 h). The stable production process was confirmed by fabricating an automatic bonding machine.

A CMOS image sensor module applied for a digital still camera utilizing the TOG (TAB On Glass) bonding method

The worlds smallest (105/spl times/55/spl times/20 mm) and lightest (130 g) digital still camera has been developed, in which a 330 kpixel CMOS image sensor chip is used as an image sensor. The authors have developed a new thinner and smaller image sensor module, called TOG (TAB On Glass) module, using the ACP (Anisotropic Conductive Paste) interconnection method. The TOG production process was established by obtaining optimum bonding conditions for both optical glass bonding and CMOS chip bonding to the TAB tape. The bonding conditions, including sufficient bonding margins, were mainly studied. The TOG module obtained good imaging properties. It also has a high reliability such as thermal cycle test (-10 to +110/spl deg/C/30 min, 2000 cycles) and the high temperature storage test (60/spl deg/C, 90%RH, 3000 h). The stable production process was confirmed by developing an automatic bonding machine.