How to Spot Old Electronic Components

One of the biggest supply chain risks that we discuss in our design guides is the risk of counterfeit electronics. Fake parts are so insidious because you often don't know a part is faked until there is a catastrophic failure. No one likes to admit that they were duped by fake parts, so it is likely that these instances are severely underreported.

If you're planning to buy from overseas distributors or brokers, there are some simple things to watch out for that might signal your parts are faked, mishandled, or just old. Old parts could also be categorized as mishandled in that they may not have been stored properly, or an old part may have been misrepresented by the seller. It's up to you as the receiver of those parts kits to know when something is amiss.

Telltale Signs of Old Parts

We've mentioned this in other places in our designs: not all counterfeit parts are outright fakes. Sometimes they are just mishandled, recycled, mislabeled, or old. Sometimes the mishandling is not a deliberate attempt to do anything nefarious, sometimes the part seller is just unaware of best practices.

No matter what the case may be, there are some very simple signs that can help identify mishandled, reclaimed, old, or faked parts in a parts kit. Let's run through each of these possibilities.

Date Codes on Integrated Circuits

Integrated circuits do not technically have a shelf life; if they are packaged properly and not exposed to the environment, they can last a significant amount of time. For example, standard packaging materials and semiconductor dies can last for decades, and component leads can still remain solderable if stored for well over a decade. The key here is that the parts have to be packaged properly so that they are not exposed to corrosive, moisture, or dust.

Still, date codes might surprise you, especially if you're ordering from the secondhand market. You might receive a batch of components that, while technically packaged properly and fully functional, could simply have an old date code. Another possibility is that your batch has mixed date codes. The problem is not that the components necessarily expire, but there are some potential problems with this:

• The part number could have undergone a revision; you might have the old revision
• The die may be functional, but the leads may need to be re-tinned
• Internal non-volatile memory may have compromised data retention ability
• The packaging material might have failed storage, leading to an environmental risk

Recycled Parts

Some parts may be recycled from an old assembly, meaning the parts were pulled off of an old PCB and placed in apparently good packaging. These parts might also be identifiable from a date code, but of course not all parts will have a date code on them. If a part is pulled from an old assembly, there could be some potential problems with these parts:

• These parts might require re-tinning before they can be reliably soldered
• The parts could have remnant solder, which could be identified visually
• The parts may have failed before being removed from the assembly
• Components may have some remnant surface coating, such as a conformal coating
• For BGAs, the components may have been desoldered and re-balled
• Remnant solder or reballing/re-tinning might have used materials with lead

Recycled parts can sometimes be identified visually because they will exhibit signs of wear, such as remnant solder as mentioned above. There is also environmental risk due to incorrect storage as they were formerly included in a PCB assembly.

Corroded Parts

Sometimes, parts are not recycled and they are not old, but due to improper handling and storage the leads may become corroded. Signs of extreme corrosion will be clearly visible on the surface of component leeds. The root cause here is failed moisture barrier storage or incorrect storage such that extreme moisture or oxidizing substances enter the storage environment.

Corrosion can technically be removed from the exposed leads on an integrated circuit. However, this will also remove the outer layer of tinning or possibly damage the leads. When this is the case, the components may need to be re-tinned, something which requires special equipment and skill.

Unfortunately, because it is not so cost-effective to re-tin components without direct access to equipment and personnel, the components might need to be trashed.

Quick Ways to Spot Old Components

If you see something that looks suspicious, there are some simple test methods that do not require a lot of equipment or an advanced lab.

• Visually inspect for discoloration on component leads
• Visually inspect for the presence of date codes
• Use acetone or rubbing alcohol to check if inked markings on packaging dissolve
• Check for solder blobs on component leads
• Check for excessive reflective areas on component leads (indicates remnant solder)
• Visually inspect the packaging to see if the packaging was resealed

A failure in any of these areas could indicate that the components have been repackaged, recycled, or have simply been sitting for a long time. Some of these issues can be eliminated when buying from the secondhand market by simply requesting a picture of the packaging with the date code. Not all dealers or brokers keep track of date codes for their inventory, but if they are trying to be legitimate then they should honor a simpler request to see a picture of the date code.

The next time you need to look for some cost savings on electronic parts and remove obsoletes/EOLs from your BOM, head over to Octapart and use the advanced search and filtration features to create your component orders. You will also find suggested alternates on Octopart’s component pages and up-to-date distributor pricing data, parts inventory, and parts specifications.

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