TD-3V Laser Inspection System
Solder-Paste Printing Inspection

Slit-Laser based Paste Print Inspection

In recent years, there has been a rapid miniaturization of electronic devices and components as well as an increase in the use of fine-pitch technology. Soldering technology must now accommodate surface-mount device leads spaced closer together -- 0.25 mm today vs. 0.50 mm previously. As a result, there is a greater potential for problems such as misregistration, smearing, clogging, and bridging.

It is therefore vital that anyone who utilizes solder paste-printing technology be able to measure the paste-print height, width, and volume. This is important in determining whether or not the quality of their printing meets their required standards. The Malcom TD-3V allows users to accomplish these tasks in a non-contact manner by employing a slit-laser for automatic inspection and 3-D inspection modes.

For automatic past-print height and width inspection, the user starts by selecting a fiduciary mark (up to 4 per board) as a point of origin.  The user then teaches the system the points to measure (up to 100 points).  Default measurement parameters may be used, as well as user-defined parameters.  After measuring the paste-print height and width, the TD-3V indicates whether the printing meets the specified standards. The settings may then be saved for future identical boards. Inspection results can be saved as well.

2-D graph of solder-paste height and width

Numerical data table of solder-paste height and width

For 3-D paste-print volume inspection, the user selects the area to be inspected as well as a measurement increment (20, 40, 60, 80, or 100 Mu meters). After completing the inspection, the paste-print volume and a color profile of the selected area is displayed.

Here are pictures of the 3-D color profiles:

The main unit of the TD-3V is connected to a PC (control unit) through a standard RS-232C cable and a BNC cable. The BNC cable connects the CCD camera (on the X axis of the main unit) to  the PC, which is equipped with a video-capture board.  The pre-loaded Microsoft Windows-based software controls the XY axis movement, the LED lights, and the laser.  The system is exceptionally easy to use.

Measurement Principle

When a laser beam is applied diagonally to a three-dimensional object, it bends according to the irregularities of the object's surface. The height of the object is then acquired by measuring the deviations of the bending line from the straight laser line. Simply put, if one were to set the position of the laser beam to 0-45º, then apply the laser beam on a rectangular object, it would be seen in the following manner: When the beam is seen from directly above, there is an X deviation between the object and the circuit board. The following equation is acquired: Height = tanØX = tan45º * X = X Therefore, X is the height of the object.

Features and Benefits

• The TD-3V Automatic Paste Print Inspection System can measure printed solder paste height and widths at up to 100 user specified locations.
• Automated X/Y movement insures accurate board to board comparisons of the same locations. After inspection, data can be viewed or printed as a table, graph, or color profile.
• The system is also capable of performing automatic 3-D volume calculations of given locations.
• TD-3V provides Statistic Process Control Data, or SPC. In the SPC, the operator will see graphs, histogram, and data. All of this information comes from raw data collected in Auto Inspection Setting. The SPC is very clear and user friendly. The operator is able to track the measurement of the individual pad.

Specifications

* Specifications subject to change without notice.