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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

Using Resistor Networks In Matched Resistor Applications

Matched resistors are utilized in many applications including sensors for commercial, medical and military markets and pulse squaring elements. However, the most common applications is resistor divider circuits for amplifier applications. This article focusses on how to avoid amplifier output errors and discusses the merits of using resistor networks instead of discrete devices.

High Voltage Resistor Design Considerations

If a high voltage resistor is to perform to specification over an extended period of time there a number of design factors to consider. In this post we cover thick film resistor construction and the impact on performance of external thermal and mechanical issues.

Thick Film v Wirewound Power Resistors – A Comparison

There are many power resistor technologies available but the most common are Wirewound and Thick Film with other technologies reserved for specialist applications

Power Resistor Design Considerations

For any resistor technology, the four main design considerations are:

-Resistance value

-The resistor power handling capability

-The change in the resistance value over time

-The change in the resistance value with temperature

Passive Electronic Component Obsolescence Solutions

Resistors and other passive electronic components can often become difficult to source or obsolete at short notice causing delays to production schedules, upsetting important customers and wasting resources. Often, an attempt may be made to purchase residual stock from distribution or component brokers but this can lead to issues with quality or counterfeit components. As many manufacturers may be chasing the same solution the correct component can be both difficult and expensive to source.

The Main Causes Of Thick Film Resistor Failure

Thick film resistor failures are often caused by external environmental factors such as electrical and mechanical stresses and handling issues but seldom occur due to a failure of the resistive element itself. Failures are either classed as a degradation of performance or complete failure (usually as an open rather than a short circuit).

We consider several common causes of thick film resistor failure, many of which may not be immediately obvious to the circuit designer. Failure modes include:

·         Mechanical stress

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