When choosing resistors for use in demanding applications there are many issues to consider.
However, sometimes design compromises are not an option and custom thick film resistors are the only solution. In this post, we consider the advantages and disadvantages of choosing a bespoke resistor specifically designed for a particular application.
Custom Thick Film Resistor Advantages
The sensible approach is to choose a standard ‘off the shelf’ resistor product wherever possible. However, in many applications selecting a standard resistor requires some design compromises.
Beyond the obvious resistor parameters of resistance, tolerance and power rating there are many other issues to consider. Transient and environmental conditions can have a major impact on resistor performance over time.
Choosing a standard resistor can be a false economy if the resistor performance degrades over time or the resistor fails. With careful selection of a custom resistor, there are no design compromises.
In some applications, a custom thick film resistor is the only option. Even with appropriate design compromises, a standard resistor product may not be available.
The major resistor manufacturers tend to focus on resistor products for standard, relatively high volume, applications. Applications with extreme environmental conditions, particular performance requirements, severe transient conditions or dimensional/form factor constraints may not be supported by volume manufacturers.
With a focus on volume and standard devices, the major resistor manufacturers also tend to obsolete devices that are no longer considered commercially viable. A custom resistor product designed as a form, fit and function replacement for the original device can be one solution. With custom resistor devices generally available in low to medium volume this approach may be used as a stop-gap approach until a system redesign is scheduled or a standard device becomes available
Disadvantages Of Choosing Custom Thick Film Resistors
Perceived high cost (compared to standard products) tends to be one reason custom solutions are avoided. Most system manufacturers prefer standard products as they tend to be on short lead times and can be sourced as and when required. Custom thick film resistors tend to be single sourced and this is considered a potential threat to long term system availability by some system manufacturers.
Cost for a custom solution will always tend to be higher than a standard part but this needs to be measured against the cost of system failure if too many design compromises are made. By working with a specialist custom resistor manufacturer the impact of some potential disadvantages of a custom resistor solution may be minimised. With appropriate planning lead times can be minimised and the single sourced problem may be addressed.