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TAB Placement Accuracy Enhancement Via Compensation for Component Skew

IP.com Disclosure Number: IPCOM000107379D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 107K

Publishing Venue

IBM

Related People

Corbin, JS: AUTHOR [+2]

Abstract

This article describes a rotational placement correction that improves lead-to-pad registration of TAB devices by compensating for the inherent skew in the device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

TAB Placement Accuracy Enhancement Via Compensation for Component Skew

       This article describes a rotational placement correction
that improves lead-to-pad registration of TAB devices by compensating
for the inherent skew in the device.

      A typical TAB package is shown in Figure 1 with the major axis
length Lmajor and minor axis length Lminor being defined as shown.
Ideally, the major and minor axes are normal to each other, but in
reality, the device will be skewed as a result of handling, the
excise and form process, etc.  Device skew represents the degree of
distortion from an ideal rectangle to a parallelogram and is
characterized by the skew angle THETAskew . TAB sites (also shown in
Figure 1), on the other hand, typically are much less skewed.

      The placement task involves positioning the TAB device such
that its centroid coincides with the site centroid, and performing a
final rotational correction such that the device is angularly aligned
with the site.  When a device is skewed, there is no rotational
correction that will align every lead with every pad. This article
describes an optimal rotational correction in the sense that the mean
peripheral lead-pad registration error is minimized.

      Existing TAB placement tools utilize multi-camera inspection
systems that inspect the TAB device before it is placed on the panel.
The inspection task includes the determination of the device skew.
Skew is measured by determining the orientation angles THETA1 and
THETA2 of the device major and minor axes with respect to the panel
coordinate frame.  The angle THETA1 represents the orientation of the
device major axis with respect to the board frame X-axis; the angle
THETA2 represents the orientation of the device minor axis with
respect to the board frame Y-axis.  B...