Paul,

Your picture shows no wetting in PTH and along the lead except at the bottom
lead tip.  Such severe non-wetting could be due to - a) contamination on lead
and on the PTH inside and or b) outgassing through copper inside PTH. You may
have to run analysis on component lead for contamination and raw PCB to see if
plated copper has voids ( thin porous copper). If outgassing is the predominant
mechanism, then you will also see solder balls on the top side of PCB assembly.

If you can post a clean xsection picture of one of the joints in question, it
may provide some more clues. The  analysis to determine the exact cause
(mechanism)  will require more detailed information and inspection of the
failed assemblies. Please call directly if you need further help.


Paul Tomlinson wrote:

> Hi folks,
>
> I am just learning about these matters, and this is THE place where
> knowledge and experience abounds so please somebody help me with this.
>
> I have just had my first ever boards waved and the results are not
> encouraging.  What could be the cause of a volcano shaped void between the
> component leads being soldered and the main body of the solder?
>
> There is perfect continuity, the area at the tip and that around the board
> are well wetted, but mechanically the joints are very weak and prone to
> failure, the parts can actually be pulled out of the board without being
> damage.
>
> Could this be simply the result of a too low temperatured wave?  They used
> 465F.
>
>                        |       |
>                        |       |
>                        |       |
> --------------------- |       | -------------------
>                      | |       | |
>                      | |       | |
>                      | |       | |
> --------------------- |       | -------------------
>            *         * |       |  *         *
>           *         *V |       | V *         *
>            *       * O |       | O  *       *
>             *      * I |       | I  *      *
>               *    * D |       | D  *    *
>                 *   *  |       |   *   *
>                   *  * |       |  *  *
>                     * *|       | * *
>                      * |       | *
>                       *|       |*
>                        ---------
>
> This ASCII art is extremely crude so I have attached both JPG and BMP files
> of a much better drawing.
>
> Tia,
>
> Paul.
>
>   ------------------------------------------------------------------------
>                Name: lead.bmp
>    lead.bmp    Type: Bitmap Image (image/bmp)
>            Encoding: base64
>
>                Name: lead.jpg
>    lead.jpg    Type: JPEG Image (image/jpeg)
>            Encoding: base64
>
>   ------------------------------------------------------------------------
>
> END --------------------- [log in to unmask] END
>
>        Raising teenagers is like trying to nail Jell-O to a tree.

--
____________________________________
Regards,
Pratap Singh

Tel./Fax: 512-255-6820,
e-mail: [log in to unmask] or [log in to unmask]

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