The Power of Generic Parts

Author: Saar Drimer / Published on: 21 September 2023

Creating a bill-of-materials (BOM) for electronics is sometimes an underappreciated art form. It’s a process critical to projects’ longevity and success, yet it doesn’t always get the credit it deserves. The primary challenge is reconciling the many criteria competing for a BOM line item, or ‘socket’: price, board space and technology, availability, sales-reps attention, evaluation kits and samples availability, experience, and many more. Making a definitive choice requires a great amount of skill to do well. Here we’ll only discuss the merits of defining generic parts, rather than specific manufacturer part numbers (MPNs), and then focus on what works best with Eurocircuits’ assembly process [1].

Defining a generic part is where designers specify the required parameters a part must have instead of an MPN. This is usually useful for passive components and common connectors where there are many different parts that satisfy the required properties. A generic resistor, for example, could be defined by its required parameters, “220Ω 0603 1% 0.125W”, meaning that any resistor that meets these specific requirements is acceptable, ignoring other ones such as temperature coefficient or specific manufacturer (although the assembler may take these into account for manufacturability).

The alternative to using ‘generics’ is defining MPNs. The ‘problem’ here is that the assembler might not have it in stock, so they’d need to order it. That takes time. It’s not so bad if the parts are readily available for order… but if they aren’t, there will be delays. Specifying a generic part allows our assembly house to choose from the components that they have in stock, or order them from their suppliers using their buying power to significantly reduce the likelihood of delays.

Finally, designs are more robust when alternate (an equal) or substitute (a less capable) parts are also defined. This helps assemblers identify a suitable ‘generic’ by having more information to work with (for example, if they cannot fully parse the list of required parameters) [2]. Listing alternate and substitute parts are helpful in general, not only for generics, when the ‘main’ MPN becomes unavailable and a few years down the road when a new board revision is made.

Generic components at Eurocircuits

The best way to use the power of generic components is to put the GPN – taken from resistors and capacitors or the parts search in the PCBA Visualizer – in the MPN column of the bill of materials that’s uploaded to the Visualizer. At the time of writing, when the price of a GPN component, at checkout, is less than or equal to €0.02 we offer it for free!

When an order is complete the order’s ‘passport’ – that can be downloaded from the user area – will include the actual MPN used as the generic. This way customers are able to use that MPN specifically in future order from Eurocircuits or from other assemblers.

We provide information about how to generate a BOM that’s compatible with the PCBA Visualizer here, and information about our preferred suppliers here.