IEC 62321-2:2021 pdf free download – Determination of certain substances in electrotechnical products
4.3Complexity of electrotechnical products and related challenges
The complexity of electrotechnical products impacts the sampling and can have a bearing onthe practical execution of sampling and analysis. The following elements are identified asrelevant to sampling and testing:
a)Miniaturization: miniaturization is one of the key trends in the electrotechnical industry. It implies that more functionality is provided within a smaller volume.An increased number ofparts and diversity of materials are used per cm2 of printed circuit board (PCB) every year.Taking samples for measurement from these small amounts of material is difficult.Forexample, the size of surface mounted devices(SMDs) is too small for regular tools to furtherdisjoint or separate and the quantity of the remaining sample is often too small afterdisjointment to satisfy the requirements of adequate analysis.
b) Number of homogeneous materials: many parts have complex structures and are constructed of multiple layers of different materials. Typically a single electronic part hasbetween 10 and 20 materials，whereas many electrotechnical products or assembliescontain hundreds or thousands of parts. This means one electrotechnical product can havebetween 1 000 and 10 000 homogeneous materials.Often, homogeneous materials adheretoo tightly together for a clean separation in a practical manner.Experience shows that thecomposition often changes due to molecular diffusion between materials (e.g. thecomposition of a plating is affected by a base material containing lead). Similarly, present-day electrotechnical products are made of many parts.A typical TV or laptop computer, forexample, contains thousands of parts.Hence the design database for an OEM may includeseveral tens of thousands of parts. Iln Annex E this point is further illustrated in thedisassembly of a mobile phone.
c) Oxidation states of certain substances may not be stable over time.For example,the concentration of hexavalent chromium in corrosion protection layers can changesignificantly with time and storage conditions.
d) Visually undetectable substances: another complicating factor in sampling and testing is that often certain substances are not visible without supplemental action or opticalenhancement. A part containing a certain substance may look and perform in an identicalmanner to one that does not contain it. While there are sometimes visible indications of thepresence of certain substances (e.g. a yellow coating on steel products suggests thepresence of hexavalent chromium), visual detection is not practical.
e) Batch-to-batch variations: most product manufacturers use commodity parts that may come from multiple suppliers simultaneously，for example cables，resistors and capacitors.Commodity parts are mixed during production because technically they are fullyinterchangeable, as long as they fit the umbrella specification. However, in most cases theyare not chemically identical. Furthermore，experience shows that the materials can bechanged by commodity part suppliers (e.g. in times of shortage) which leads to a change inthe chemical composition of that part. Notification of these changes is not always providedif the part still meets its technical specification.
f) Depth of the supply chain: producing electronic parts often involves a complex supply chain.Relatively simple products，such as an external cable,can utilize supply chains at leastseven tiers deep. The supply chain for a more complex part such as an LCD screen, isconsiderably deeper.
These characteristics of the electrotechnical industry show that the management of certainsubstances,along with sampling and testing, is not straightforward.The size and number ofparts,and complexity of the supply chain make it challenging to fully grasp the locations ofcertain substances in an electrotechnical product.The prospect of impiementing homogeneousmaterial level sampling and testing at the upper tiers of the supply chain (towards finishedproducts) is not practical for complex products.
4.4Sampling procedure
The sampling strategy describes the process to be followed to determine the sample. This isthen followed by the actual preparation of the samples and is finalized with the testing. Whiledifferent approaches for sampling and testing are likely to apply to different electrotechnicalproducts, it is possible to describe a generic process that will be applicable in the majority ofcases.This is illustrated by the iterative process shown in Figure 1.