Wee Mei:
There is another approach at applying adhesive to the
package instead of to the leads. Make a bead that runs on the board up
the corner of the package and over the top of the package, repeated four
times ( one on each corner).
As far as the heel fillet it has to be up half the curve of the
heel per J-Std-001 9.2.6.1. The customer may buy the strengthening of
the package to the board bond by adding the adhesive, specially if it
passes all tests.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wee Mei
Sent: Monday, February 06, 2006 6:24 PM
To: [log in to unmask]
Subject: Re: [TN] Gull wing side & toe fillet height
Hello,
Since the discussion is about gull wing package, I would like to ask one
question : "Is there a minimum requirement for heel fillet"? The reason
I asked is that we encounter soldermask inside the via-in-pad for solder
pads.
As a result, the heel of the gull wing package happen to rest over this
via-in-pad that has soldermask inside. Being a TQFP64 package and pad
width of 16mil with the via diameter as 12mil, there is hardly any room
to provide solderability to the back of the lead heel. If you can image,
there isn't or very little possibility of solder fillet that can be
formed at the heel.
For me I would consider this as failure. However, the board is urgently
require and would be ESS, can enhancing the soldered leads reliability
by applying adhesive over them help?
Looking forward to your reply,
Thanks,
Wee Mei
----- Original Message -----
From: "Rex Waygood" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, February 07, 2006 1:03 AM
Subject: Re: [TN] Gull wing side & toe fillet height
> IPC 610 Rev D ( 8.2.5.4???) Side Fillet is by length and evidence of
> wetting, no height.
> The reason you cannot find a toe requirement is that there is not one.
> Components often have a pre-plated cropped end so it isn't necessarily
> wettable. You are also allowed toe overhang of the pad.
> Rex
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of sumxp
> Sent: 06 February 2006 15:23
> To: [log in to unmask]
> Subject: Re: [TN] Gull wing side & toe fillet height
>
> Sorry,I am referring to side and toe fillet Height.
>
> Thanks
>
> sumxp
>
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