A.N.,
Fabrizio is correct that the PCB finish influences the soldering. However, poor soldering can influence the operation of the LEDs. Since all of the LEDs work immediately after assembly and a few stop working sometime later, it sounds like you may have a few resistors that are not soldered well. I would suggested a detailed inspection of the resistors especially those associated with the LEDs that are not working to see if you have good solder joints.
Regards,
George
George M. Wenger, Andrew Corporation
Reliability / FMA Engineer
Base Station & Subsystems Group
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Fabrizio Ramari (framari)
Sent: Wednesday, September 29, 2004 5:47 AM
To: [log in to unmask]
Subject: Re: [TN] Reliability issue in 0402 soldering
The PCB finishing influence the soldering not the function .
Fabrizio
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Janoch Jirí, Ing.
Sent: Wednesday, September 29, 2004 11:34 AM
To: [log in to unmask]
Subject: Re: [TN] Reliability issue in 0402 soldering
Hi,
we use PCB ENIG surface for tiny components but I would say that PCB tin
surface does not influence on LED function.
J.Janoch, Des. Dpt.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Prasad AN
Sent: Wednesday, September 29, 2004 10:14 AM
To: [log in to unmask]
Subject: [TN] Reliability issue in 0402 soldering
Hi all
We are assembling around 750 # of 0402 size LEDs in small PCB of size
65mm X
65mm.
The problem we are having after reflow, when PCB is tested all the LEDs
are
glowing.
But after some time the problem starts with 3-4 LEDs not glowing.
The PCB surface is of Tin plating.
Let me know is the PCB surface is suitable for this type of board. If
not
what type of surface is recommended for PCB with only 0402 LEDs.
Thanks with Warm regards
A.N.Prasad
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