Electronic Design

Solder Pad Adjustment Eases LED Second Sourcing

Not all LEDs are the same. But despite blatant differences—dimensions, performance levels, solder pads, and processing options—a lot of LEDs can be substituted in and out of most designs if they physically fit the board or housing. This not only saves time and money via simpler design procedures, it also can ensure product longevity when required.

Osram Opto Semiconductors has responded with a concept for uniform solder pads based on its Oslon LED family. These pads promise to make it much easier to use LEDs from different manufacturers on the same board design, a practice known as second sourcing.

According to the company, second sourcing is standard operating procedure for LED components. In an ideal world, Osram says, it should be possible to swap second-sourced components into current production without added costs. Yet components from different manufacturers differ in both size and solder-pad shape, resulting in the need for separate soldering boards for each maker’s LEDs.

Using Osram’s concept for ceramic LED components, the company claims only one adjustment to the board layout is necessary. This adjustment makes the board’s solder-pad design adaptable for LED components from at least two different manufacturers. It is also viable for grooming metal core, FR4, and ceramic boards. The company says that only a small adjustment to the process is needed.

In basic terms, the combined board design evolves from the design of one of the two different LEDs. Individual solder surfaces are separated and dedicated to being either electrically connected or electrically disconnected. Once the appropriate spacings between the solder surfaces are set, the second LED is rotated 90° so it can be attached to the board design.

The anode and cathode of the two LEDs share the same electrically contacted points. In turn, dividing the solder surfaces allows the two different LEDs to automatically align on the edges of the solder pads during reflow soldering (see the figure).

Osram’s adapted solder pad design enables two different LED types to operate effectively on one board.

The luminous area for the two diverse LEDs retains the same lateral board position. If both LEDs exhibit similar emission behaviors, there’s no need to use different secondary lenses and/or reflectors. The characteristics of the LEDs and the end application aren’t changed in any significant manner.

Osram’s concept and adjustment makes it significantly easier to use LEDs from different makers since there is no need to modify the board. Also, there are no dual-storage issues or related costs. Sometimes the simplest approaches yield the best results.

Osram Opto Semiconductors

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