| Objectives | Background | Approach |
To develop guidelines for the design and manufacture of
electronic systems for use in automotive underhood applications,
focusing on issues of materials compatibility and process
compatibility at high temperatures.
Significant cost, size, and weight savings can be achieved by replacing traditional centralized control systems with a more distributed architecture, where the sensors, processors, and actuators are all housed in a single, remotely placed, unit. The savings result from the elimination of cables, interconnects, and environmental controls. The elimination of these historically unreliable elements also has the potential to significantly increase the reliability of the electronic system. Distributed control systems also improve maintainability since these systems are integrated field replaceable units (FRU), thus eliminating the need to troubleshoot electrical problems in the field.
The challenge of distributed control is that it requires the electronics to be operated at the ambient temperature of the remote location. These temperatures exceed the traditional maximum allowable operating temperatures of 70°C to 85°C for commercial systems and 125°C for military systems. The classic example of this type of environment is that encountered by an automotive engine control system, where temperatures can range from -40°C when unpowered on a cold winter day to 165°C when powered on a hot summer day [Erskine, 1995]. Modules designed for such applications can require new materials and manufacturing technologies which must examined for compatibility with the other materials in the system and the manufacturing processes used to construct the module.
To satisfy current product development needs for shorter development and product lifecycles, along with faster times-to-market and times-to-profit, assurance of reliability cannot be based on test-analyze-fix methodologies. Instead, a whole new paradigm for design for reliability is needed, which is called application specific design for reliability. It is a methodology that assesses the reliability of systems and modules based on the fundamental mechanisms by which they fail. Using this approach, modules and systems can be qualified quickly at a minimum cost, with the amount of qualification testing reduced to that necessary to validate the reliability assessment, using parameters tailored to minimize the test time. This project will build on the studies done in C98.5-17 and C00-24 to demonstrate the use of this methodology to examine the materials compatibility and design issues involved in developing an organic-based engine control module for a high temperature underhood application.
In this project, we will demonstrate a methodology for conducting design-for-reliability of high temperature electronic systems that will address issues of component availability and testing, materials compatibility, process compatibility, and durability. This will complement the previous work in high temperature electronics that focused on the overstress temperature limits for individual materials and packaging elements. Critical areas to be investigated will include developing a database of currently available high temperature active and passive components, implementing materials selection criteria, documenting the current state of the art in high temperature solder development, and examining the effect of high temperature soldering on system design.