Older Micron TSOP packages advertise a feature, “off-center parting line.” What does this refer to? Is this a feature of the lead frame? I have heard that OCPL has some vague mechanical reliability or maybe packaging yield benefits. Can anyone discuss OCPL in more detail?


1 Answer 1


Seems to be a mechanical arrangement that allows packages to be stacked. From a patent.

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From paragraph [0027],

The top package 102 is mounted over the bottom package 110, such as a TSOP having an off-centered parting line (OCPL) as shown by the position of a bottom lead 112 off-set from center within a bottom pack age body 114. It is understood that the bottom lead 112 may be a portion of a lead frame (not shown).

Probably a more modern solution would be to stack dies inside the package, if necessary, to increase density.

  • \$\begingroup\$ What specifically is the "parting line" being referred to here? \$\endgroup\$
    – Hearth
    Sep 21 at 23:46
  • 1
    \$\begingroup\$ @Hearth Generally the parting line is on the leadframe plane, so I would assume 122 or 104 or 112-- well, I might as well just look at the reference. Ah here we go. Well, might as well just add the relevant section since I'm looking at it--. Yep, 112 it is. \$\endgroup\$ Sep 22 at 0:30
  • \$\begingroup\$ @TimWilliams Thanks. It's hard to imagine the part coming out of the mold if the parting line was not on the same plane as the leadframe. \$\endgroup\$ Sep 22 at 0:42

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