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Algorithm to Detect Solder Bridge On Printed Circuit Board

IP.com Disclosure Number: IPCOM000119962D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Nakano, H: AUTHOR

Abstract

Disclosed is an algorithm to detect typical types of defects appearing between leads of a surface mount component attached to a printed circuit board. The areas between the leads are scanned along the leads to detect defects, such as solder bridge, bent lead and undesirable solder deposit (Fig. 1).

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Algorithm to Detect Solder Bridge On Printed Circuit Board

      Disclosed is an algorithm to detect typical types of
defects appearing between leads of a surface mount component attached
to a printed circuit board.  The areas between the leads are scanned
along the leads to detect defects, such as solder bridge, bent lead
and undesirable solder deposit (Fig. 1).

      In this method, the image of the leads is taken by a camera and
stored in the frame memory of an image processing system.  A
rectangular window is set to define the area of interest in the
image, as shown in Fig. 2.  Both side edges of the window must
overlap with adjacent leads or solder pads.  All pixels between the
leads, in this example between the solder pads, are scanned
vertically, as shown by arrows. Conductive portions, such as leads
and solder, will be higher in brightness than the surface of the
board.  A check is made for each of the vertical pixel lines as to
whether it includes one or more predetermined number of pixels of
higher brightness than a predetermined threshold.  The number of
vertical lines which do not meet the condition is counted.  If no
defect exists, then the count will show a maximum value.  If solder
bridge exists, then the count will be zero.  If an isolated solder
deposit or bent lead exists between the solder pads, the count will
be between zero and the maximum value.  Therefore, by setting a
proper detection threshold, defects can be effectively detected....