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Subject:
From:
"Gumpert, Ben" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gumpert, Ben
Date:
Wed, 8 Nov 2017 19:30:04 +0000
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J-STD-075 speaks to process restrictions for both SMT and PTH parts, and directs the use of J-STD-020 and J-STD-033 for moisture sensitivity classification and handling of both.

But I can't remember ever seeing this standard used.

Ben

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D
Sent: Wednesday, November 8, 2017 12:06 PM
To: [log in to unmask]
Subject: EXTERNAL: Re: [TN] Moisture-Sensitive PTH LEDs

I have not seen exactly this issue, but have seen other PTH components that were actually SMDs embedded within a through-hole package, very similar to your situation, but not LEDs.
I not only reviewed J-STD-033, but also J-STD-020 which is the methods used for moisture sensitivity classification.
J-STD-020, like J-STD-033, starts off saying that the methods used are for classification of SMT devices. No mention is made of PTH devices.
I do not know of any industry standard that addresses either the classification or handling of non-SMT Moisture Sensitive parts, but I do believe it should be addressed.
If any such IPC or JEDEC standards DO exist for PTH parts, then references should be made within both J-STD-020 and J-STD-033 directing the user towards them.
For some components such as DIP ICs that are also commonly formed in gull-wing configuration for SMT use, for example, the component manufacturer should comply and label them accordingly if in fact they are MSDs from a reflow standpoint, even if they are not "technically" required to do so. Ditto with components that are actually flip-chip LEDs encapsulated inside of a lens on a PTH platform.
But no matter what, PTH or SMT, if the parts are moisture sensitive, they should be classified and labeled as such to meet the intent of the standards.

Because parts from one manufacturer may be MSDs of a Level 3 and from a different manufacturer Level 5a, and from yet another manufacturer not MSDs at all, there is no way any MRP system can keep track of them if they are not labeled as MSDs by the manufacturer. As a result, for many companies the only means of notification that any package contains Moisture Sensitive parts is if there is an MSD label on the outside of the Moisture Barrier Bag and packaged to meet the dryness requirement. This is common sense, and any reputable component manufacturer would have an implied responsibility to follow that best practice no matter what the package type or assembly process possibly used, wave, selective, manual, or reflow. 

If they require dry handling and bake-out to survive the assembly process, they should be labeled accordingly.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ron Feyereisen
Sent: Wednesday, November 08, 2017 9:06 AM
To: [log in to unmask]
Subject: [TN] Moisture-Sensitive PTH LEDs

Hi Technetters,

Just wondering if anyone has come across this issue-

We're being asked to Wave process assemblies that use small 3mm through-hole LEDs. We started to see a high failure rate during product testing of these LEDs and the root cause investigation found that, after verifying that the profile was per recommended, the LEDs are stated on the datasheet as being moisture-sensitive and require baking after 72 hrs being out of the original bulk poly bag packaging. (not a moisture barrier bag)

The manufacturer's original packaging is insufficient to protect against moisture absorption since it's not a MBB, does not state the LEDs are moisture-sensitive and do not contain desiccant nor a humidity indicator card. Since J-STD-033 only refers to surface mount devices, what other industry controls are in place to identify moisture-sensitive through-hole devices such as these? The 72 hour requirement should be handled as MSL 4 but the manufacturer is saying that it only applies to SMDs for the marking and packaging. We do not want to have to bake these LEDs each time we run the assy, as well as mitigating defects.

Any suggestions for recourse on this issue? It'll be much appreciated!

Thanks,
Ron

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