Have you ever considered sourcing inexpensive components from China? The temptation is strong, we know that. And we've already gained some experience, a few of which I'd like to share.
Dangers of second-source components: 3 practical examples from medical technology
1) Pulse-resistant resistors
A customer wanted the high-quality, pulse-resistant, and precise resistors from Metallux replace it with a cheaper second-source variant from China.
The datasheet? A virtually identical copy of the original resistor.
The result of the pulse test? The cheaper option literally gave up the ghost; it simply burned out.
2) Second Source – intentional or not
Chinese manufacturers often replace original parts with cheaper second-source components, sometimes deliberately, sometimes without consultation. This can work, but it also carries significant risks.
A good example is JST connectors, which are widely used and therefore often counterfeited. The "compatible" alternatives often look deceptively similar to the originals, but tolerances are critical, especially with small connectors. Second-source products likely do not undergo the same comprehensive testing and verification as the original JST connectors.
We have already experienced that the combination of an original JST connector on the circuit board and a second-source connector on the battery leads to sporadic problems. Visually, the differences are barely noticeable – for example, only upon close inspection (with a microscope) of the manufacturer's logo. But sporadic failures in the field are particularly frustrating. Therefore, we consistently require our suppliers to use only original parts.
3) USB power adapter
USB power supplies are required for many electrical products. Besides their electrical functionality, they must possess all relevant certificates and test reports for CE conformity. And this is precisely where many suppliers fail: either the documents are completely missing, or only partial proof is provided – e.g., EMC conformity, but no basic safety certification.
We thoroughly test all the components we source.
During the evaluation of a USB power supply with complete CE documentation, we noticed the following:
Do you see the mistake?
He is highlighted in the following image:
An electrolytic capacitor is placed directly across the separation gap. This renders all air and creepage distances irrelevant – a clear design flaw.
The measurement of conducted interference was also above the limit:
We have informed the distributor and will continue to carefully evaluate the components we source.
Conclusion for manufacturers and developers in medical technology:
Not all experiences with Chinese suppliers are negative – we have been working successfully with some for years. And European suppliers have also delivered defective components in the past, particularly during periods of limited availability.
Therefore, the saying goes: prevention is better than cure.
And if you need support in evaluating components, just contact us. We're happy to help!
And if you need support in hardware development, then take a look here: Hardware development