From: RussellMc <apptechnz@gmail.com>
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Date: Tue, 4 Aug 2020 16:22:13 -0700
Subject: Re: [EE] "Sunlight" brand LEDs
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On Wed, 5 Aug 2020 at 02:16, Neil <picdude3@narwani.org> wrote:

> The failures I had with the counterfeits were random segments failing
> within weeks, months or more, and replacing a 12-pin through-hole
> display on a very tight PCB was a very difficult task, so the boards had
> to be replaced.
>

1. Possible source.
May be about as reputable as any of the Asian sources
https://lcsc.com/products

2. There are too many variables known only to you or not known at all to
offer anything like certain advice.
Depending on quantity involved, acceptability or possibility of redesign,
time available, knowledge of failure environments my approach MIGHT include
these semi random thoughts:

Any possible clues from environment? - temperature cycling or extremes,
vibration, hours of use, voltages,  ...

Soldering temperature or profile affected? Could torture test bad units to
see if relevant.

Are old "bad" versions available for comparison testing?

Are mechanical aspects a factor - twisting or differential cooling or
vibration or ... ?
(Not directly relevant, but as an example, small slices from PV panel
wafers have stress issues which many manufacturers seem unaware of).

Test rig?
High end currents?
On off cycling? Whole power supply square wave?
Hot cold cycling - maybe in and out of refrigerator every day or so while
running?
Vibration ? Doable "simply enough" if liable to be relevant.

I can envisage a module with N displays, mounted on a woofer to provide
vibration, cycled on and off grossly and powered on long enough wires to
allow it to be moved in and out of a refrigerator easily.
Mix of liteon (1 or 2), old bad units (few), Sunlight samples.
Not overly "controlled"- but at 3 hours/day usual operation (if on time is
relevant) that gives you 8 months per month.

ANY segment failures are probably too many.

Statistical rule of thumb is if you get no results in N samples then actual
figure is - hmm - mind says either < 1 in N/3 or < 1 in 3N. If that sounds
of relevance it can be checked.


  Russell



>
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