Are Vf matched LEDs always more expensive then non Vf Matched LEDs?

[treez]

Hello,

Are Vf matched LEDs always more expensive then non Vf Matched LEDs?

i.e. concerning "families" of LEDs which are matched and families of LEDs which aren't Vf matched.

 

[D.A.(Tony)Stewart]

When produced from many wafers, the process controls produce a range of voltages as specified by the specs. The range of voltage is due to the range of ESR's because the threshold voltage is the same for chemical reasons but the thickness and bulk resistance (ESR) varies.

To request few bins or single bin will cost more and depends largely on your relationship with your supplier and most of all, high volume. i.e. >10K~25K per order.

Without going into details, the few bins, the lower the yield and the higher the cost.
Generally a production run from the same batch of wafers may give a 2 bin range out of 3 or more for most of the product for Vf parameter with 0.2V bins for most.


Generally low efficacy LEDs have wide variation in process controls and wider variations in ESR and Vr. While higher efficacy higher power LEDs are controlled to maximize yields for high efficacy which tends to lower the ESR variations in %, which translates into tighter controls of Vf., but these tend to have premium costs associated with this. Newer Epitaxial growth machines which make the wafers are sold most LED chip producers also reduces Vf variation in high brightness modules.. ( eg for TV backlight LEDS)

I often get parts from the factory matched < 1% when they come from the same wafer. This is normal for me, but rare if you get parts from distribution.

What are your requirements? for tolerance and volume?