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High Surge Capability Thick Film Resistor Design

When surge or pulse conditions occur in electronic equipment resistors are often used to suppress the pulse and prevent damage to sensitive electronic components. Traditionally wire wound resistors were the technology of choice but today thick film surge resistor technology provides a cheaper, non-inductive, solution with a significantly smaller footprint.

Key Power Resistor Application Considerations

When choosing a power resistor for any application it is important to consider more than the resistance value, power rating and tolerance. There any many factors that can affect the performance of the resistor, and the system as a whole, including thermal and mechanical issues and operational life.

Thermal Issues In Power Resistor Applications

Thermal performance has a direct impact on both mechanical issues and operational life and should, therefore, be the first issue to consider.

Snubber Resistors In Power Electronic Applications

Snubber resistors are used in a variety of power electronic applications as circuit protection elements.

Thick Film Heater Elements In Medical Applications

Thick film heater element are used in a wide variety of applications including incubation of cultures, to heat fluids before injection, DNA analysis and diagnostic equipment. These applications require controllable heat to be delivered to a specific area, often over an extended period of time, with a uniform steady state.

Power Resistor Derating For High Temperature

In complex electronic systems, the issue of power resistor derating for high temperature can often be overlooked. The system designer may have many design issues to consider. Passive components, such as power resistors, are often the last to be evaluated, if at all.

Advantages of A Resistor Network vs Discrete Devices

In many electronic systems discrete resistor devices are more than adequate but when reliability and performance are of prime concern and space is limited a resistor network can be a better choice. Resistor networks offer a number of advantages including: 
• Space Saving.
• Reduced resistor drift due to temperature and power variations.
• Lower cost.
• Improved System reliability.
Each of these issues is considered in more detail below.

High Voltage Resistor Applications

High voltage resistors are used in a wide range of applications including Power supplies, ESD protection, Electron Microscope, Air Ionising equipment, RADAR equipment and ATE. Example circuits include high voltage bleeder, voltage balancing, voltage regulation and voltage dividers. In this post, we discuss the key issues affecting the choice of a resistor in each circuit.

Thick Film Power Resistor Mounting Considerations

Inappropriate thick film power resistor mounting can severely compromise the resistor performance. In this post, we cover the key points to consider

Position on System Board

As current passes through a resistor it generates heat that in turn induces stresses in the power resistor device as a result of differential thermal expansions of the resistor materials. This heat must be dissipated or the resistor performance and/or its lifetime will be compromised.

Power resistor ESD sensitivity

The most common cause of power resistor ESD damage is a direct transfer of an electric charge from either a human body or a charged material to the power resistor device. ESD damage may be divided into three main categories

1.       Parametric failure

The ESD event alters the resistance of the power resistor device causing it to shift outside its specified tolerance

2.       Catastrophic Damage

The Difference Between Pulse Power and Pulse Voltage Resistors

Pulse resistors are employed as simple surge protection elements in many electrical circuits. A key design decision is the choice between pulse voltage resistors and those capable of withstanding a high current as the design of one is the exact opposite of the other. For pulse current handling the width of the resistive element is maximised but for high voltage pulses, it is designed to be long and narrow.

Pulse Handling Resistor Design

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