Document Type

Thesis

Date of Award

2003

Keywords

Metal oxide semiconductors, Complementary, Metal oxide semiconductors, Complementary Image processing -- Digital techniques, Metal oxide semiconductors, Complementary Image processing -- Digital techniques, Digital electronics, Digital imaging

Degree Name

Master of Science (MS)

Department

Systems Science and Industrial Engineering

First Advisor

k. Srihari

Second Advisor

Nagen Nagarur

Third Advisor

Robert Murcko

Abstract

The world of optoelectronics merges diverse fields, such as physics, optics, electronics, chemistry, and material science. It leads to more advanced and efficient applications by exploiting the properties of light, which is typically a more effective data and energy transfer medium than electron flow. A couple of well-known applications are the optical imagers and sensors used for cameras, scanners, and barcode readers. The two prominent image sensor types are Complimentary Metal Oxide Semiconductor (CMOS) image sensors and Charge Coupled Devices (CCDs). While CMOS sensors have traditionally performed well in new applications, such as Personal Computer (PC) cameras (where CCDs were deemed too expensive), the year 2002 has seen CMOS image sensors begin to make headway into the digital camera market, a stronghold of the CCDs. CMOS sensors, by the virtue of their lower price, lower power consumption and higher level of integration, have a significant advantage over CCDs in this market. In the past, the quality of CMOS imager’s video had been inferior to CCDs. However, with CCDs being more expensive, consuming greater amounts of power, and requiring complicated supporting circuitry, more research was applied to improve CMOS imaging.

The research focuses on a special type of optical image sensor commonly referred to as Linear Image Sensor (LIS). The LIS series is a family of high performance linear image sensors designed for a wide variety of applications. These devices excel as a superior CCD replacement for Edge Detection, Contact Imaging, Bar Code Reading, Encoding and Positioning and Text Detection. These packages, prior to their intended usage, must be qualified according to the industry standard reliability tests. Therefore, accelerated life testing was conducted on the LIS series package, to support a designed life of 10 years operating at 65°C. Prior to conducting any life test, the structural design and the material system of the package was evaluated by using Finite Element Analysis (FEA). The composite system utilizes different materials for the various components comprising the package. Once the package leaves the manufacturing floor, it is exposed to different environments. From storage, shipping, and assembly to the real time use, they undergo a wide variety of stresses including temperature and humidity. A good package must be properly designed to ensure material compatibility. The package must withstand all environmental conditions, and should perform its function for the required lifetime.

The LIS packages were subjected to a regime of standardized life tests according to JEDEC (Joint Electron Device Engineering Council) standards. Tests were conducted to evaluate the performance of the package for an equivalent ten-year usable life. The following standardized tests were conducted qualifying the package at moisture sensitivity level 3 (IPC/JEDEC J-STD-020A): temperature cycling (JESD22-A104-B), steady state temperature humidity bias life test (EIA/JESD22-A101-B), and temperature bias and operating life (JESD22-A-108-B). Except for the thermal cycle tests, all life test evaluations required the components to be operating during the exposure utilizing custom designed hardware (motherboard, daughter card, etc.). Because of the problems with the reflow solder process caused by an excessive gold thickness on the printed Circuit boards, the 85°C/85%RH and the High Temperature Operating Life(HTOL) test samples required 100% solder touch up. A failure occurred at the end of life, but could not be isolated to the package. However, this failure was included in the failure prediction of 62 FITS (Failure in Time) or 0.054% failures per year. The package is deemed t o be a robust design for the intended application.

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