Browse Prior Art Database

Multi-function Through Hole for High Performance Flip Chip Bonding

IP.com Disclosure Number: IPCOM000123586D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Shohji, I: AUTHOR [+4]

Abstract

Disclosed is a multi-purpose through hole structure in the printed circuit board for flip chip bonding. The through holes can offer a high performance flip chip bonding process with low cost.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 80% of the total text.

Multi-function Through Hole for High Performance Flip Chip Bonding

   Disclosed is a multi-purpose through hole structure in the
printed circuit board for flip chip bonding.  The through holes can
offer a high performance flip chip bonding process with low cost.

   The through hole structure is shown in Figure 1.  A few
through holes are existed symmetrically in the flip chip bonding
site.  The larger the hole number is, the more the effect is.  The
diameter of that hole is under 0.5mm.  The diameter should be enough
to avoid an encapsulant leaking.  The plating of through hole surface
is not needed, because the purpose of our through hole is not to
spread heat.  Any treatment for the through hole surface is not
required.

   The main function (purpose) of our through hole is as
follows:
  1.  Loophole for bubbles produced from flux on reflow
      soldering
  2.  To improve the solvent flow into the flip chip joint area
      on cleaning
  3.  Loophole for voids on encapsulant applying
  4.  To improve the encapsulant flow time

   This structure can achieve to apply an encapsulant with
low cycle time.  Generally, an encapsulant is applied from one side
of the flip chip, and the process is paused until the encapsulant
flows another side.  On the other hand, when through holes are
existed in flip chip bonding site, the voids and encapsulant are
pulled in that hole, finally the encapsulant flow time is improved.
Then, the applying encapsulant...