practical guide to the packaging of electronics thermal and mechanical design and analysis

[...]... pressure between the PCB and the guide, the lower the thermal resistance Typical values range from 20°F in/watt for the U or G guides to 10 °F in/watt for the Z type guides to 4 °F in/watt to wedge clamps 2-D OR 3-D HEAT CONDUCTION It is possible to form a network of thermal resistance elements to cover an area (2-D) or a volume (3-D) and then write the equations to balance the heat in and out of the system... thick and the enclosure wall thickness is 0.10 inches The top surface of the enclosure (on the smaller PCB side) is mounted to a surface that is virtually a thermal isolator The voltage and current supplied to this system is 16 volts at 20 amperes and it operates at 80% efficiency The top PCB is smaller than the other two and dissipates V? of heat generated by the other two boards Furthermore, the top... calculating the component critical temperatures Mechanical analysis is concerned with the housing of the electronics (from component housing to PCB to enclosure and finally to the rack) as well as the ability of this housing to maintain its integrity under various loading conditions such as shock and vibration Thermomechanical management is concerned with the impact of thermal loads on the mechanical. .. ELECTRONICS PACKAGING DESIGN Let us assume that you have the responsibility of developing a new electronics system Let us also assume that your budget allows you to bring a team of experts together Where do you begin? Who do you hire? It does make sense to hire a team of electronics engineers to design the PCB's and people to lay out the boards and maybe even those who will eventually manufacture them... loads on the mechanical behavior of the system In this work, we will set the foundation for thermal and mechanical analyses of electronics packaging/ enclosure design Reliability While in my view thermal, mechanical, thermomechanical and EMI analyses are subsets of Reliability analysis, most engineers consider reliability calculations to cover areas such as mean time to failure (MTTF) or mean time between... set of equations, these equations are not simple to solve nor can they be readily used to evaluate system performance or be used to set design criterion Generally, it takes sophisticated computer hardware and software to solve these equations The significance of these equations may be numerated as follows 1 They produce exact solutions of any thermal/ flow problems 2 These equations could be reduced to. .. through the PBC into the Heat Sink As it was pointed out, it is customary to specify the copper thickness in terms of its weight Each ounce of copper denotes a thickness of 0.0014 inches Therefore, 2 oz copper provides a thickness of 0.0028 in As for proper via area calculation, one only has to be mindful that the via has a hole in the middle and the area for conduction is the area of the donut shape The. .. need to develop to answer this question? This guide is developed precisely to answer this question Our objectives are: • To develop a fundamental grasp of engineering issues involved in electronics packaging • To develop the ability to define guidelines for system's design - when the design criteria and components are not fully known • To identify reliability issues and concerns • To develop the ability... applications, an Integrated Circuit (1C) or a hybrid must be designed specifically for particular tasks Detailed discussion on this topic is beyond the scope of this book Packaging/ Enclosure Design There are four topics that I categorize under packaging and enclosure design and analysis These are electromagnetic, thermal, mechanical, and thermomechanical analyses We will not cover electromagnetics here,... majority seems to have an overheating problem There is a fan to cool the system, but it is not enough, you decide to add another one but to no avail Well, your patience runs out and you decide to hire the thermal engineer after all His initial reaction is that thermal considerations have not been built into the PCB design but after a few weeks he manages to find a solution, however, it is expensive and cumbersome . w0 h0" alt=""