Zhaga gets smart - Section 3 - Reducing arbitrary variation: the COB Book
Posted on Thursday October 6 2016, by Zhaga
This article was published in the Proceedings of the 2016 LED Professional Symposium+Expo (September 2016).
Author: Dee Denteneer, Secretary General, Zhaga Consortium
In a previous LED Professional article , we reported on the specification describing LED modules that typically use COB technology. As is common in Zhaga, the specification focuses on the mechanical and electrical interfaces, and specifies values for parameters such as physical dimensions, electrical contact positions and light-emitting surface (LES) diameter.
To illustrate the Zhaga way of working, and its impact, we refer to Figure 2. When starting the COB specification, Zhaga made an inventory of the dimensions of the COB modules available from 13 major manufacturers. The right-hand panel of Figure 2 shows the x- and y-dimensions of these COB modules. The panel reveals a state of high entropy, with many similar form factors.
As discussed in Section 2 of this paper, small and arbitrary size variations are of limited value. Also, the form-factor proliferation incurs a lot of cost to the industry. Costs multiply for the COB module manufacturers, who have to maintain a portfolio of many slightly different form factors, but also for manufacturers of auxiliary components, such as holders and lens-plates, who need to supply components that match all COB form factors. And not least, this form-factor proliferation complicates life for the luminaire makers, both in terms of their second-supplier strategy and alos for inventory management.
Zhaga’s market analysis resulted in a set of 6 form factors (in blue in Figure 2) that appropriately cover the breadth of available form factors in the main market ranging from 12-28 mm. Full coverage of considerations is given in .
The right hand panel in Figure 2 repeats the analysis, and investigates the market place one year later, upon completion of the COB Book. It shows that the support for the form factors adopted by Zhaga has grown. Table 1 makes this more quantitative and specifically shows that, immediately after the Book’s completion, support for the “Zhagafied” form factors had increased significantly, while the support for non-Zhaga form factors remained stable.
From another perspective, the analysis also shows that there is considerable market support for one particular non-Zhaga form factor. More in-depth analysis revealed that a small, square COB array was needed in the market, yet was missing from the Zhaga specification. This has resulted in a follow-up activity to add this form factor to the Zhaga Book.
A number of telling conclusions can be drawn from this COB example. The Zhaga specification was based on a thorough market analysis, conducted by players from all segments in the value chain, with the aim of removing arbitrary variation. This approach is successful, and considerably increases the support for those form factors adopted by Zhaga. Finally, continuous market surveillance and iterations may be needed to maintain a high-quality specification.
Figure 2: Impact of Zhagafication on number of manufacturers supporting specific dimensions, before and after publication of the Zhaga COB Book, from a sample of 13 manufacturers. Blue = Zhaga form factors; black = non-Zhaga form factors; circle size = number of manufacturers.
Table 1: Impact of Zhagafication on number of manufacturers supporting specific dimensions, before and after COB Book, from a sample of 13 manufacturers.
 "Chip-on-Board LED Modules Standardized in Zhaga Book 12" by Martin Creusen, Charles Knibbeler, Manfred Scheubeck, Ingo Arnrich, and Nico van Stiphout, LED Professional Review, Sept/Oct 2015.