December 11, 2014…The Zhaga Consortium, which develops specifications for interchangeable LED light sources, is now working on a new Book that will include Chip-on-Board (COB) LED arrays. COB arrays are in widespread use, but different manufacturers offer a wide range of alternative sizes. The consortium notes that this creates problems for luminaire makers and other stakeholders such as COB holder suppliers and limits their options of using alternative products from different suppliers.
“We consulted many luminaire makers, and received broad support for our plans to standardize this type of LED light source,” said Musa Unmehopa, secretary general of the Zhaga Consortium.“These companies asked us to standardize properties such as the mechanical dimensions of the module, the position of electrodes, and the diameter of the light-emitting surface.”
Zhaga says its standardization removes arbitrary variations in a small number of parameters, to allow interchangeability of LED light sources. The consortium contends that for customers, standardization simplifies the comparison and selection of products. The consortium says that it allows COB-array makers to focus on offering value-added differentiation to customers, such as luminous efficacy, quality of light, or thermal properties.
“For Zhaga Books to be successful, they need to reflect the wishes of the market,” said Unmehopa. “We welcome any input from COB makers or other companies, who are invited to join Zhaga and contribute to the ongoing discussions.”
The new Zhaga Book will define rectangular and square LED modules with a circular light-emitting surface (LES) and a separate LED driver. The Book will define a family of modules with different dimensions. In the majority of cases, modules that are compliant with the new Book will employ COB technology* for the light-emitting section. However, the Zhaga specification will not prevent the use of alternative technology approaches.
After extensive discussion the consortium decided to specify a family of six rectangular or square modules, with the following PCB dimensions: 12 x 15 mm, 16 x 19 mm, 19 x 19 mm, 20 x 24 mm, 24 x 24 mm, and 28 x 28 mm.
The circular LES sizes defined in the new Book will correspond to the LES categories specified in several current Zhaga Books that cover spotlight modules (Books 3, 5, 10 and 11). COB LED arrays are used both with and without holders, depending on the luminaire type and application. The consortium expects that the new Zhaga Book will also include specifications for these holders.
In common with other Zhaga specifications, the new Book will only restrict the parameters necessary to enable interchangeability. In addition to PCB dimensions and thickness, such parameters are likely to include the location of the LES centre point; the position and size of the electrode positions; and the location of the thermal measurement point.
Screw holes will be optional, since many COB arrays are mounted directly using a thermal interface material. However, if screw holes are used, then their position and size should conform to the Zhaga specification.
Zhaga plans to discuss whether other features should be part of the specification such as a current-setting resistor to the board, for example, or the adding a temperature sensor to prevent over-temperature operation.