RoHS and REACH teach us that substances and chemicals used in electronics are not to be thrown away, and can be toxic to nature. So, we create laws and standards that restrict us from using metals from restricted mines and smelters, and substances that can infect nature when disposed of.
At the end of life of any electronic product we have rules on how to separate the most toxic elements, home appliance electronics are taken back by the shops and manufacturers, we dismantle and recycle. And so the process goes on.
We reject good products
My question in this discussion is: Why do the Electronic industry reject good products, when it’s not always needed?
Every year fully functional PCBs are scrapped, due to cosmetic “failures” not approved, is this right, or do we need to make an even more precise set of rules on how to handle this. Not only to avoid unnecessary claims but also save the environment? Can a more conscious approach and education on what to be considered as failures – help make the industry “greener”?
Form fit and function – not functioning?
The defects I address in this column can be small scratches, solder mask discoloration, minor copper residues, inclusions and other defects. All minor, and either accepted by IPC A-600 and IPC-610, or not mentioned. So, why are such issues not in the standard?
If you look at IPC A600 it focuses on issues that affect form fit and function.
A rule that is repeated in almost every chapter is acceptability, unless it reduces the spacing, hole diameter, or linewidth below the limits specified in the procurement documentation.
Meaning the designer should give restrictions for minimum insulation-distances allowed on the finished PCB.
My experience is that very few designers provide this information, which means we shall follow default rules according to the IPC standards. But, that also brings us to the all the open questions IPC calls AABUS that IPC requires to be discussed between user and supplier (worth a column itself!). In addition to these documented issues, we have the cosmetic gray zone.
Solder Mask related cosmetic defects
Most of the cosmetic defects we observe today are related to solder mask. Such issues could be discoloration caused by a thickness variation, small scratches that come from handling in the PCB factory, but also in transportation and at the customer side during unpacking, inspection or even in the assembly process. It could be solder mask defects over dielectric areas, inclusions of small particles that meet IPC A-600, but are rejected by the inspector.
What is the risk of using a product with cosmetic defects?
Defining risk is never easy. Some industries are clear on risk, such as Medical, Automotive and Defence. Still we have a term in the Medical standards that calls for judgement: ALARP, which stands for “as low as reasonably practicable”, or ALARA (“as low as reasonably achievable”), a term often used in the regulation and management of safety-critical and safety-involved systems.
The ALARP principle is that the residual risk shall be reduced as far as reasonably practicable. If the medical sector accepts this, we should be able to use this method for most of our PCBs for those grey zone areas where the standard leaves to customers and suppliers to find solutions themselves.
As mentioned, IPC uses the term AABUS, As Agreed Between User and Supplier. If you read the IPC standard you will find this term used all over, and frankly speaking, causing much frustration.
Because we all want clear rules to avoid conflicts between the customer and supplier. However, things are not always that simple. Some cases need to be discussed to be able to come up with good solutions.
Often the challenge can arise when the customer is not the decision maker. The product owner has strict requirements, and to be on the safe side the Electronic Supplier that assembles the PCBs, prefers to be even a bit stricter than his customer, to be on the safe side.
Some might be reluctant to ask for approval of defects not directly mentioned in his customer quality requirements. That’s when the acceptability grey zone develops to a challenge between the two.
At the end of day the customer often wins these discussions, and we end up throwing away good products that could have been used.
Can we continue wasting good products?
In a world where a clean nature is getting more and more rare, we must look at every way to avoid pollution. Even if we are able to remove a lot of the toxic substances, we will never be able to remove all of them sufficiently.
Electronics with their bromides, heavy metals and other substances harmful to nature will from time to time leak out.
Of course the challenge with throwing away fully functional electronics, can be seen as a minor issue, when tons of plastic and electronics are thrown away by the consumers every day. Still – all efforts count. And, we have no good reason to waste good products!
A shout out for a greener world!
If all of us accept the risk level such as the medical secor’s ALARP, we should be able to reduce this unnecessary pollution by accepting minor cosmetic defects, accepting rework of minor solder mask defects such as scratches, pin holes and exposing copper.
None of this increases the risk for failure in assembly, or in the final application.
I am not talking about defects that can affect soldering or product function. We will never jeopardize product quality!
Cooperation and improvements
To improve today’s situation, we need to juggle two thoughts at the same time. Accept cosmetic defects (that are within IPC standards), but at the same time talk together and find good solutions. We need to work with continuous improvements, use automatic screening tools and accept rework before the boards are shipped.
As an advisor between customers and PCB suppliers I am working with improvements every week. My target is to reduce such cosmetic errors to a minimum, but still I have to accept the fact that PCB production might involve cosmetic issues. In my opinion, the best way to avoid this is a 100% automatic production and better cleanrom conditions.
The ultimate scenario would be a production without the “green oil” (my chinese friends word for solder mask) that causes so many issues – but we are still years away from that. However, it’s all about the baby steps – baby steps towards better decisions, more knowledge around the level of acceptance of cosmetic failures, better guidelines and eventually less scrapping of perfect PCBs.
After all, a small step towards a greener industry – is better than no step!
This column was first published in the PCB Norsemen March 2020 edition of the 007 PCB Magazine.