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Problem on 0402 package

Former Member

Hello,

 

the company which mounts my boards complains about EAGLE 0402 package.

They say "the pads are too much large" and a lot of components are lost

during the soldering (reflow) due to the "tombstoning" effect.

 

I'm wondering if anyone ran through this problem, because I'm sure the

EAGLE library is ok.

 

Anyway, I don't know what tell them. In fact, they ask me a charge for

new components and manual soldering (it means it's my mistake).

 

Marco

 

Parents

  • Marco Trapanese <marcotrapaneseNOSPAM@gmail.com> wrote:

    I'm wondering if anyone ran through this problem, because I'm sure the

    EAGLE library is ok.

     

    I just recall the 0402 pads were too large for the comoactness U

    required, so I did my own. Could it be that they are meant for wave

    soldering? Google for tombstoning and you will find out why this happens

    on very light components. Pad size and position IS critical.

     

  • in reply to Former Member

    Morten Leikvoll schrieb:

     

    I just recall the 0402 pads were too large for the comoactness U

    required, so I did my own. Could it be that they are meant for wave

    soldering? Google for tombstoning and you will find out why this happens

    on very light components. Pad size and position IS critical.

     

    Yes. And I remember that in a german mailing list the IPC pad size

    suggestions have been discussed contrarily - obviously they tend to be

    too large in many cases for whatever reason, even when specified for

    reflow soldering.

     

    The probability of tombstoning rises significantly if the pads extent

    too much beyond the part - the melting paste pulls the part up. The pads

    should be more "under" the part's contact than "besides" it.

     

    Tilmann

     

  • in reply to Former Member

    Am 03.08.2010 08:24, schrieb Tilmann Reh:

    Morten Leikvoll schrieb:

     

    >> I just recall the 0402 pads were too large for the comoactness U

    >> required, so I did my own. Could it be that they are meant for wave

    >> soldering? Google for tombstoning and you will find out why this happens

    >> on very light components. Pad size and position IS critical.

     

    Yes. And I remember that in a german mailing list the IPC pad size

    suggestions have been discussed contrarily - obviously they tend to be

    too large in many cases for whatever reason, even when specified for

    reflow soldering.

    ........

     

    As far as I remember there was a change for the 0805 package in the

    past. The

    reason was that the original pad sizes did not allow to lay, I believe,

    a 0.3mm track

    between the two SMDs.

     

     

    --

    Mit freundlichen Gruessen / Best regards

    Richard Hammerl

    CadSoft Support -- hotline@cadsoft.de

    FAQ: http://www.cadsoft.de/faq.htm

     

     

Reply
  • in reply to Former Member

    Am 03.08.2010 08:24, schrieb Tilmann Reh:

    Morten Leikvoll schrieb:

     

    >> I just recall the 0402 pads were too large for the comoactness U

    >> required, so I did my own. Could it be that they are meant for wave

    >> soldering? Google for tombstoning and you will find out why this happens

    >> on very light components. Pad size and position IS critical.

     

    Yes. And I remember that in a german mailing list the IPC pad size

    suggestions have been discussed contrarily - obviously they tend to be

    too large in many cases for whatever reason, even when specified for

    reflow soldering.

    ........

     

    As far as I remember there was a change for the 0805 package in the

    past. The

    reason was that the original pad sizes did not allow to lay, I believe,

    a 0.3mm track

    between the two SMDs.

     

     

    --

    Mit freundlichen Gruessen / Best regards

    Richard Hammerl

    CadSoft Support -- hotline@cadsoft.de

    FAQ: http://www.cadsoft.de/faq.htm

     

     

Children
  • in reply to Richard_H

    Richard Hammerl schrieb:

     

    >> Yes. And I remember that in a german mailing list the IPC pad size

    >> suggestions have been discussed contrarily - obviously they tend to be

    >> too large in many cases for whatever reason, even when specified for

    >> reflow soldering.

    ........

     

    As far as I remember there was a change for the 0805 package in the

    past. The

    reason was that the original pad sizes did not allow to lay, I believe,

    a 0.3mm track

    between the two SMDs.

     

    I think that was a change to the EAGLE libraries, but not to the IPC

    standard (which still doesn't allow that track under a 0805 package, IIRC).

     

    Tilmann