Printed Circuit Boards are the rigid structures that have geometrical patterns etched on their surface. These patterns are made of copper or conductive material and replace the use of electrical wiring in electronics. Printing the circuits is less expensive than fitting wires and soldering them.
On the other hand, multi-layer boards with wiring make systems highly complex. If a defect occurs in an inner layer of the multilayer board, then all the other layers above that layer need to remove to reach that layer. This generates the need of proper inspection before lamination.
Among the various types of inspection techniques, infrared inspection uses heat and requires the use of current. The purpose of inspection is to find defects in printed circuit boards which if not corrected timely could lead to electrical failure.
Defects in the PCBs can result variations in temperatures. Inadequate or improper soldering at joint can cause electrical resistance. As a result, the temperature of the PCB increases and can be detected with the help of infrared camera.
The idea behind printed circuit board inspection with known standards is based upon the fact that heat emitted in the part of the PCB that is inspected is predictable. This idea behind inspection can be affected by the elements and methods used for printed circuit board fabrication. The substrate contains numerous electrical components, such as semiconductors, that generate heat of varying temperatures.
The idea of image subtraction involves the use of software that forms a perfect thermal profile which can be compared to the actual inspection results or even subtracted from them. The outline can be loaded into the inspection camera or it can be used from computer system.
One main thing in various types of inspection is presence of current to facilitate necessary heat generation requirements. There are mainly two types of infrared inspections, active and passive.
In active infrared inspection of printed circuit board, the device is given energy as it would be serve the actual purpose and heat produced by different electrical units is measured. On the other hand, passive infrared inspection on printed circuit board involves the current directed on the tracks in the PCB to a heat sink.
Before conducting the printed circuit board infrared inspection, the professional inspectors properly examines the job and makes selection for the best inspection tools. During selection of equipment, the inspector considers various factors like color options, field of view, and limitation associated with the physical structure of the equipment. Each inspection techniques have its own set of issues and the selection of equipment plays major role. The selection of right equipment avoids re-testing.
The printed circuit board inspection enables defects to be detected before they become a major cause of failure.
No comments:
Post a Comment