From: Neil <picdude3@narwani.org>
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Date: Tue, 4 Aug 2020 20:26:30 -0700
Subject: Re: [EE] "Sunlight" brand LEDs
Thread-Topic: [EE] "Sunlight" brand LEDs
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On 8/4/2020 7:22 PM, RussellMc wrote:
> 1. Possible source.
> May be about as reputable as any of the Asian sources
> https://lcsc.com/products

LOL yeah... that's where I found these.
PS: I did find the company's website ( sunlightled.cn ) and several=20
things broken, so could not find English datasheets, but I requested them.

> 2. There are too many variables known only to you or not known at all to
> offer anything like certain advice.
Expected.

> Depending on quantity involved, acceptability or possibility of redesign,
> time available, knowledge of failure environments my approach MIGHT inclu=
de
> these semi random thoughts:
>
> Any possible clues from environment? - temperature cycling or extremes,
> vibration, hours of use, voltages,  ...

Vehicle cockpit.  Hours can vary significantly.  Mostly trailer queens=20
(an hour an year?) to daily drivers (few hours a day every day), though=20
this may extend to commercial vehicles that'll do 8+ hours a day.


> Soldering temperature or profile affected? Could torture test bad units t=
o
> see if relevant.
Temps are generally the lowest that would work, and we still use leaded=20
solder, whereas these parts should be able to handle lead-free solder. =20
So I don't feel that's an issue.  I can tell you that we use red, blue,=20
orange and some green originals.  When Lite-On made the blues scarce, we=20
found that broker "stock" which had the (significant) issues.  Same=20
process, PCBs, environments, etc.


> Are old "bad" versions available for comparison testing?

Not sure if I have any stock of the bad ones on hand.


> 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).
Comparison with originals and other colors says that these are not factors.
I'll add that this is one of the original displays (running as a clock),=20
It was in my car for over a year at first, but since then on my desk (so=20
a much kinder environment) running continuously for > 10 years now...=20
http://orlandorobotbuilders.com/stuff/Con_Rod_Clock_01.jpg


> 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.
In the early days, I used to do the refrigerator and toaster oven test=20
quite a bit, until I was confident all was great.
I've done vibration testing only minimally, but on a dashboard it's not=20
a major factor.
Not sure what you mean by "high end currents"

> 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 i=
s
> relevant) that gives you 8 months per month.
>
> ANY segment failures are probably too many.
I agree, but trying to be realistic here.  If the product failed for=20
this reason, I've been eating the cost, even well out of warranty=20
period, as it's nothing the customer did.  I'll stomach a very small=20
number of these.  Outside of that, it's not just the cost, the there's a=20
quality-image issue here.

> Statistical rule of thumb is if you get no results in N samples then actu=
al
> figure is - hmm - mind says either < 1 in N/3 or < 1 in 3N. If that sound=
s
> of relevance it can be checked.
>
>
>    Russell
>

My usual method is to build a dozen or so protos and send them out to=20
people for testing in different environments.  Just hoping some feedback=20
from anyone who's used these might help me accelerate that a bit.

Cheers,
-Neil.

--=20
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