Under EU REACH, substance concentrations must be calculated for each each individual article, even in the case of complex objects composed of multiple component articles. (See What is an "Article" under REACH? and REACH Concentration Calculations for more information.)
Many complex objects include adhesives (such as glue or solder) used to join two or more individual articles. Because the adhesive itself is not an article, the concentration of a SVHC in the adhesive should be calculated by dividing the substance weight over the total weight of the complex object it belongs to.
For example, consider a glued chip on a bank card. The card (without chip or glue) weighs 4.5 g, the chip weighs 0.3 g, and the dried glue weighs 0.1 g. The glue is composed of 2% (w/w) "Substance X," which is on the SVHC Candidate List.
The weight of "Substance X" in the card is 0.002 grams (0.1 g x 2%).
The total weight of the complex object is 4.9 grams (4.5 g + 0.3 g + 0.1 g).
0.002 grams / 4.9 grams = 0.00041, or 0.041%. This is below the 0.1% threshold.
Diagram from the ECHA's Guidance on Requirements for Substances in Articles
Article is current as of 2020-02-21.