Pcbelectronics Thermal Management Derating Fundamentals

Master the most important concepts of cooling, thermal management and derating, with a focus on PCB development aspects.

Last updated 2022-01-10 | 4.3

- Design a PCB/electronic application using comprehensive approach to thermal management
- cooling and component derating for reliability.
- Know what heatsinks are
- their most important aspects and how to choose them for a proper thermal management and cooling.
- Undersand and choose heat sink mounting techniques and thermal interface materials.

What you'll learn

Design a PCB/electronic application using comprehensive approach to thermal management

cooling and component derating for reliability.

Know what heatsinks are

their most important aspects and how to choose them for a proper thermal management and cooling.

Undersand and choose heat sink mounting techniques and thermal interface materials.

Understand the use of fans in thermal management and cooling

their impact on heat sinks thermal resistance and parameters.

Master thermal aspects with respect to PCB routing and design (copper plane

vias and similar) and parameters influencing it.

Understand re-rating and de-rating of electronics components (derating power

voltage

currents

fan out

and so on).

Master the reliability aspects of thermal management

cooling and derating

especially with respect to electrical and thermal stress factors.

Analyse

calculate

and design the hardware thermal control of a PCB.

Cool components in PCB design using a proper approach.

Understand the most used cooling techniques and all the parameters influencing it.

* Requirements

* Knowledge of the basic electronic concepts
* like current
* voltage
* power and Ohm's law.
* Knowledge of common electronic components (transistors
* capacitors
* and other devices of widespread use) and basic PCB concepts.

Description

This course is about cooling, thermal management and derating in PCB design.

After introducing the basic definitions, it provides a clear and logical path to a complete design of thermal aspects.

- It starts with calculating the dissipated power for different types of components, and understanding whether the thermal equilibrium is optimal or we need a thermal management strategy.

- Then it introduces heat sinks, which is by far the most used cooling approach, talking about their features, mounting techniques, parameters and so on.

- Than it speaks about thermal interface materials, used to couple heat sinks to integrated circuits, their types and characteristics.

- It also speaks about the forced air cooling technique, introducing how to calculate a fan performance and its impact on the heat sink thermal resistance.

- Then it explains PCB related aspects for thermal management, of particular relevance when the used devices have exposed pads.

At the end of these group of lessons, you will be able to understand the need for thermal management and provide your design with a comprehensive strategy mastering all the related aspects and variables influencing it (like altitude, spreading resistance, etc. )

Then the course dedicate an entire section to a related and very important aspect: derating.

It explain the concept of re-rating and de-rating, its impact on electronic devices reliability and expected life (MTBF, Mean Time Between Failure, nowadays often used instead of MTTF, Mean Time To Failure), and it shows how the most used electronic components are derated and which parameters are reduced.

The course is enriched with exercises and real life examples, using real devices datasheets to show where parameters are gathered and how they are used.

At the end of the course you will have a broader understanding of the thermal/cooling management and derating aspects, and you will able to design a PCB that is able to manage the dissipated power (and related temperature rise), and properly choose components parameters based on the right derating considerations.

Therefore, you will be able to design a PCB that stands thermal and electrical stresses and that actually works and last in the real world environment.

Who this course is for:

Students interested in electronics, embedded systems and PCB design.
Students who want to understande the most important cooling techniques and basics.
Students who are interested in electronics reliability against thermal and electrinic stress.
Persons interested in derating and its impact in enhancing a device expected life.

Course content

13 sections • 55 lectures

INTRODUCTION 1 lectures

Introduction Preview 03:20

In this lesson we introduce the teacher, all the course sections and what you will be able to do at the end of the course.

BASIC CONCEPTS 10 lectures

Basic Concepts, Thermal Resistance and Power Dissipation Preview 03:31

In this lesson you will learn the basic concepts and definitions, among which, thermal resistance, junction temperature, the electrical analogy, ambient temperature, airflow and power dissipation.

Electrical Analogy

Power Dissipation Calculation Preview 05:59

In this section we will see how to calculate the dissipated power in simple components like transistors and resistors, and in more complex digital devices,
where we have to consider factors like the I/O switching power and ODT
power factor.

Power Dissipation

Example: SRAM Power Consumption Calculation Preview 05:43

In this lesson, we will apply what we have learned form the previous lesson to a SRAM digital chip Cypress CY7C1381D, whose dissipated power will be calculated as an example, using the device datasheet.

Dissipated Power Calculation

Temperature Specifications Preview 02:43

I this lesson we will see the most used temperature ranges, and we will have a quick glance at the JEDEC standard and its use, in order to be able to perform reliable comparison between thermal performance of different components.

Junction Temperature

Linear Regulators Peculiarities Preview 04:42

In this lesson we will see the peculiarities of one of the most used and more affected by the power dissipation performance devices, the linear regulators. We will see hot to calculate the dissipated power in the worst case scenario, using the data available in the datasheet.

As an example, we will see the Low Drop Out Linear Regulator Microchip TC1264.

Linear Regulators

HEAT SINKS 2 lectures

When to Use Heat Sinks Preview 06:29

In this lesson we will talk about heat sinks, how to calculate when hey are necessary, which performance is required and how to choose them for a specific device, once given the ambient temperature, the Junction to Case thermal resistance, the dissipated power and the maximum Junction Temperature allowed by the chip manufacturer.

We will provide a numerical Example, at the end of which an AAVID Heatsink will be chosen after having checked its datasheet.

Heat sinks

THERMAL INTERFACE MATERIALS (TIM) 3 lectures

Thermal Interface Materials Preview 06:05

In this lesson we will introduce thermal interface materials (TIM), which are the materials used between the heat sink and the device. We will explain the different types of TIM, with strengths and weaknesses, and we will provide an example of thermal resistance calculation with the Laird Technologies TPCM585 phase change TIM.

Notes to the Thermal Interface Material Lesson Preview 00:19

Thermal Interface Materials

HEAT SINKS MOUNTING TECHNIQUES & SPREADING THERMAL RESISTANCE 5 lectures

Heat Sinks Mounting Techniques Preview 03:42

In this lesson we will see the most used techniques to apply an heat sink onto a chip, with strength and weaknesses for each siltation. We will also provide some tips to avoid short circuits between heat sinks and nearby capacitors.

Note to the Heat Sinks Mounting Techniques Lesson Preview 00:17

Mounting Techniques

Spreading Thermal Resistance Preview 01:34

In this lesson you will learn what the Spreading Resistance is, under which circumstances it occurs and how we take into account of these aspects by augmenting the rated heat sink thermal resistance with a safety multiplication factor.

Spreading Thermal Resistance

FANS AND FORCED AIR IMPACT ON THERMAL MANAGEMENT 10 lectures

Fan Parameters Preview 04:29

In this section we will introduce the most important fan parameters (CFM, LFM) and how to calculate it. We will use as an example the Datasheet of the fan RS Pro DC Axial Fan.

We will also see a simple rule to derated the fan CFM with respect to the back-pressure.

Fans

Effects on Heat Sinks Preview 01:35

In this section we will explain how the use of a fan impact the thermal resistance of heat sinks. We will refer to the impact of the fan used in the previous lesson example, the RS Pro DC Axial Fan, on a heat sink with 9.5 °C/W thermal resistance.

Effects on Heat Sinks

Heat Sink Thermal Graphs Preview 01:55

In this lesson we will talk about the thermal resistance variation with airflow predicted by the manufacturers and reported under the form of graphs.

We will see the two most common graphs.

Thermal Graphs

Altitude Derating Preview 01:40

In this lesson, we will see how altitude impact a heat sink performance, with and without forced air flow/fans, showing a table with derating factors.

Altitude Derating

Tips Preview 01:43

In this lesson, we will give you some tips on fan and heat sinks positioning and some other advice.

Tips

PCB ASPECTS 6 lectures

PCB Thermal Aspects Preview 02:45

In this lesson we will talk about when and why the PCB design represent a critical factor in the thermal management.

PCB Thermal Aspects

PCB Thermal Resistance Calculation: Software, Graphs and Tables Preview 02:36

In this section we will explore how manufacturers provide information on a component PCB soldering and placement in order to provide a Thermal Resistance through the PCB of a specified value.

PCB Thermal Resistance Calculation

PCB Design Tips for Thermal Performance Preview 02:59

In this lesson, we will provide some tips on the PCB design and component placement in order to improve the thermal performance.

PCB Design Tips for Thermal Performance

Summary of the Thermal Management Procedure 1 lectures

Steps for Thermal Management Preview 00:44

RE-RATING AND DE-RATING 13 lectures

Stress Factors Preview 02:46

In this lesson we will talk about the most influent stress factors and what derating is. We provide an example on a resistor.

Stress Factors

Need for Derating, Mechanical and Chemical Failures, and Direct Derating Preview 01:47

In this lesson we talk about the difference between mechanical and chemical failure, and we introduce two example of direct stress factors derating, which can be applied to every stress factor but power dissipated. The latter indeed, requires one more step before derating, which is called re-rating and it is shown in the next lesson.

Need for Derating, Mechanical and Chemical Failures

Direct Derating

Derating Power Dissipation Preview 05:07

In this lesson we will talk about the power dissipation Re-Rating and De-Rating for electronic components.

We will see how manufacturers provide re-rating information for resistors and semiconductor devices, showing specific datasheets of component from Vishay and ON Semiconductor.

Furthermore, as an example, we will derate a 200W 2N6338 transistor using the graph method with the derating graph and mathematical method with the derating coefficient, both provided by the manufacturer in the device datasheet.

Derating Power Dissipation

Electrical Stress Preview 01:25

In this lesson, mostly theoretical, we will introduce a formula that describe the relation between failure rate and electrical stress, and we will show how a variation of 15% of the stress voltage, can double the failure rate.

Electrical Stress

Thermal Stress Preview 02:26

This lesson is quite theoretical, and shows a formula that relates the thermal variations to the failure rate. It shows how a variation a 10°C may double the expected life of a device.

Thermal Stress

Specific Component Derating Preview 07:37

In this lesson, we will provided the recommended derating factors for the most common electronic components, to be used when the component manufacturer does not provide information on this matter.