I'd actively press the manufacturer for data on why they classified the connector as MSL 5a. It costs money to ship parts in MBB's; hopefully, they didn't make that decision without some kind of data.
Alternately... this might be too simplistic of an approach, but you could expose a few connectors, and then run them through a reflow process once or twice.
A header like this is a very simple part. There's no wire-bonded die or thin leadframe involved. I'd suspect that any moisture delamination damage that would adversely affect the connector would be pretty apparent.
Assuming you can tolerate the risk, and in the absence of data from the manufacturer, if there isn't anything visibly or electrically wrong with the connector, I'd probably ignore the moisture warnings.
Again, that "assuming you can tolerate the risk" is a big caveat...
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Wednesday, May 13, 2009 3:23 PM
To: [log in to unmask]
Subject: Re: [TN] Nylon connectors - moisture sensitivity
This is a shrouded header, 2mm spacing on the pins. Basic. Nothing high frequency.
It is surface mount, it is designed for reflow. This one is specified that it can withstand one reflow of 260C for 10 seconds.
When this connector arrived, it was in MBB packaging.
When we asked about that, we were told, 'treat it as equivalent to 5a MSL'. This is the first time I have ever heard of a basic connector being MSL.
We received it on tape and reel.
However, we were told that if it is out of MBB for longer than 24 hours that we should bake at 120C for 4 hours.
We will have to take it out of T&R to do that, which means it would need to be repackaged.
I should clarify - when I talked about melting connectors I was talking in general terms, not this specific connector. I'm sure we've all melted a connector from time to time.
I was trying to understand what would happen, what kind of damage would we see, if it was moisture-laden and we reflowed it anyway?
Genny
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
Sent: May 13, 2009 1:22 PM
To: [log in to unmask]
Subject: Re: [TN] Nylon connectors - moisture sensitivity
Genny,
first of all, you should ask yourself :
- what is the system impedance (50 Ohm or MOhms)
- signal levels
- current levels
- DC?
- AC?
- data lines?
- wave form?
- S/N requirements?¨
- Insulation requirements (flashover risk)
- pin/sleeve basic metal?
- ditto plating?
- migration condtions?
- nylon reinforcement?
Then you can judge the situation and decide what level of risk.
In certain situations not even Teflon is satisfactory.
Inge
----- Original Message -----
From: "Genny Gibbard" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, May 13, 2009 8:43 PM
Subject: [TN] Nylon connectors - moisture sensitivity
We have been told that a surface mount nylon connector we use is
moisture sensitive, and should be treated as equivalent to level 5a.
This is the highest level we have ever seen on any component we have
used of any type. I didn't think that a connector could be moisture
sensitive. Not heat tolerant, yes - we have melted a few - but moisture
sensitive?
What kind of damage can happen to a nylon connector from too much
moisture absorption?
Thanks in advance for your responses.
Genny
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