Basic Guide To Resistor Selection

Step 4 - Supplier / Manufacturer

By this stage, the resistor’s electrical characteristics, mechanical format, and underlying technology have been clearly defined, marking the technical work done. Unfortunately, this is not the end of the selection process, as resistors that exist only as line items on a schematic are not useful unless they can be sourced reliably, consistently, and at an acceptable cost. Supplier and manufacturer choice is thus not an administrative detail, but a core part of engineering risk management.

Budgets, Constraints, and Procurement

Every project operates under constraints, and that is a universal fact. Budget limits, approved vendor lists, regional availability, and lead times all affect what parts can realistically be used. In many organisations (especially larger ones), engineers do not have full control over procurement decisions, where purchasing teams may substitute parts, consolidate suppliers, or chase lower prices without fully understanding the technical impact on the final design. This disconnect is where problems tend to start, especially with components that appear simple and interchangeable, such as resistors.

Quality and Reliability

The primary reason supplier choice matters is quality and reliability, as reputable resistor manufacturers invest heavily in process control, material consistency, and testing. Their datasheets are accurate, their tolerances mean what they claim, and their long-term drift and failure rates are well characterised. When a design specifies a resistor from a known manufacturer, it is rarely done meaninglessly. Swapping it for an unknown equivalent may look correct on paper, but can have a serious impact on the final design, even if the nominal value and package look identical.

Counterfeits

Counterfeit components remain a persistent problem in the electronics supply chain, and resistors are no exception (the COVID pandemic amplified these issues massively due to supply chain shortages and disruptions). However, it's important to understand what the term counterfeit actually means. Counterfeit parts are not just those that are fake pretending to be an official part; even old official parts incorrectly stored and sold, or those pulled and recycled from old devices are all considered counterfeits.

Thus, counterfeit resistors can be relabelled parts, rejects sold as compliant components, or entirely different technologies packaged to look convincing. Such parts can pass basic inspection and even initial testing, only to fail under stress, temperature cycling, or extended operation. The consequences of using counterfeit parts ranges from small nuisance failures to full-on product recalls, regulatory issues, and legal exposure. Because of this, trying to save a a fraction of a cent per resistor makes little economic sense.

Distributor

Choosing the manufacturer alone is not enough; even the distributor matters just as much (possibly even more). Authorised distributors have formal relationships with manufacturers and are bound by storage, handling, traceability, and documentation requirements. They can provide certificates of conformity, clear lot tracking, and predictable supply. Proving such infrastructure comes at a cost, which is why authorised parts are rarely the cheapest option (but exists for good reasons).

Grey Market

Unauthorised (grey-market) distributors occupy a more ambiguous space. Some will operate professionally, deliver genuine components, often at competitive prices or with better availability during shortages, and can even exceed standards of those followed by authorised distributors. Others, however, may source parts through opaque supply chains with unknown storage conditions, multiple re-sales, and limited traceability. These components may have been exposed to excessive humidity, temperature extremes, or mechanical stress before arriving at the customer. Making matters worse, at any point in the supply chain, genuine parts can be substituted with counterfeits, intentionally or otherwise.

This doesn't mean that grey-market sourcing is always wrong, but it does come with a higher risk compared to authorised distributors. Such parts require incoming inspection, electrical verification, and an acceptance that traceability may be incomplete. For low-risk, non-critical designs, that trade-off may be acceptable. For safety-critical, regulated, or high-reliability products, it universally unacceptable.

It should also be stated that there have been times (albeit rare) where even authorised distributors have been found to distribute counterfeits. These parts typically enter their supply chains in edge cases such as excess stock by back.

The practical recommendation for manufacturer / distributor selection straightforward. First, specify resistors from well-known manufacturers with a track record of quality and stable production. Second, source them from authorised distributors whenever possible. Thirdly, where substitutions are unavoidable, ensure they are technically equivalent and properly reviewed rather than silently swapped at purchase time.

Resistors may be simple components, but the supply chain behind them is not. Ignoring that reality is a reliable way to turn a finished design into a recurring problem.