TECHNET Archives

November 2017

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Stadem, Richard D" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D
Date:
Wed, 8 Nov 2017 18:34:35 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (1 lines)
Excellent post, absolutely spot on!

On the back page of J-STD-033 is the form for suggesting improvements to the Standards. Fill it out and send it in.

IPC, are you listening?

dean





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Ron Feyereisen

Sent: Wednesday, November 08, 2017 12:02 PM

To: [log in to unmask]

Subject: Re: [TN] Moisture-Sensitive PTH LEDs



We wish to avoid having to bake brand new LEDs since the labor and time involved to do so is not covered in the quote for the job- yet. Plus, the manufacturer should ensure that their LEDs are free of moisture at the time of receipt. We will then ensure that our own handling of the LEDs follows industry standards such as J-STD-033. Also, the suggested bake time, per the datasheet, is 30 hrs!



I'm surprised to see that J-STD-033 hasn't been updated to include through-hole components since now days it's becoming common that even some through-hole components are very moisture-sensitive. In years past when parts were larger, it wasn't much of an issue, hence the SMD-only J-STD-033 standard. This manufacturer refusing to label and MBB pack their MSL 4-like sensitive LEDs only because they are not SMDs is not helping anyone. Without saying who they are, they are a popular LED manufacturer- so beware!



Thanks to everyone for their helpful comments!



Ron





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry Dzaugis

Sent: Wednesday, November 08, 2017 11:17 AM

To: [log in to unmask]

Subject: Re: [TN] Moisture-Sensitive PTH LEDs



Good luck getting the manufacture to label and package correctly.



In the mean time, add bake out to the receiving inspection instructions and seal in a MBB properly labeled.

You will be able to use them with the same SMD procedures currently in place.

Easier to square it away at receipt rather than when pulling from stock.







On Wed, Nov 8, 2017 at 12:05 PM, Stadem, Richard D <[log in to unmask]

> wrote:



> 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

>


ATOM RSS1 RSS2