Automated inspection is a technology based on the same principles as automated optical inspection

Automated optical inspection

Automated optical inspection is an automated visual inspection of a wide range of products, such as printed circuit boards , LCDs, transistors, automotive parts, lids and labels on product packages or agricultural products...

 (AOI). It uses as its source, instead of visible light, to automatically inspect features, which are typically hidden from view.

The increasing usage of ICs (integrated circuit

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

) with packages such as BGAs (ball grid array

Ball grid array

A ball grid array is a type of surface-mount packaging used for integrated circuits.- Description :The BGA is descended from the pin grid array , which is a package with one face covered with pins in a grid pattern. These pins conduct electrical signals from the integrated circuit to the printed...

) where the connections are underneath the chip and not visible, means that ordinary optical inspection is impossible. Because the connections are underneath the chip package there is a greater need to ensure that the manufacturing process is able to accommodate these chips correctly. Additionally the chips that use BGA packages tend to be the larger ones with many connections. Therefore it is essential that all the connections are made correctly.

AXI is often paired with the testing provided by boundary scan

Boundary scan

Boundary scan is a method for testing interconnects on printed circuit boards or sub-blocks inside an integrated circuit. Boundary scan is also widely used as a debugging method to watch integrated circuit pin states, measure voltage, or analyze sub-blocks inside an integrated circuit.The Joint...

 test, in-circuit test

In-circuit test

In-circuit test is an example of white box testing where an electrical probe tests a populated printed circuit board , checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assembly was correctly fabricated...

, and functional test.

Process

As BGA connections are not visible the only alternative is to use a low level inspection. AXI is able to find faults such as opens, shorts, insufficient solder, excessive solder, missing electrical parts, and mis-aligned components. Defects are detected and repaired with in short debug time.

These inspection systems are more costly than ordinary optical systems, but they are able to check all the connections, even those underneath the chip package.

Related technologies

The following are related technologies and are also used in electronic production to test for the correct operation of electronics printed circuit boards.

• In-circuit test
  In-circuit test
  In-circuit test is an example of white box testing where an electrical probe tests a populated printed circuit board , checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assembly was correctly fabricated...
  
   (ICT)
• Joint Test Action Group (JTAG)
• Automated optical inspection
  Automated optical inspection
  Automated optical inspection is an automated visual inspection of a wide range of products, such as printed circuit boards , LCDs, transistors, automotive parts, lids and labels on product packages or agricultural products...
  
   (AOI)
• Functional testing (see acceptance testing)