MDA, Manufacturing Defect Analyzer

The Manufacturing Defect Analyser or MDA is a tool that uses in-circuit test techniques to enable the detection of manufacturing defects within a printed circuit board.

Automatic Test Equipment, ATE Includes:
In-Circuit test, ICT ICT technology & techniques Flying probe Manufacturing defect analyzer, MDA ICT fixtures ICT design for test
See also: ATE basics PCB inspection techniques Functional test, FATE Developing test strategy

The Manufacturing Defect Analyser, MDA is a basic form of In-Circuit Tester.

As the name implies, the MDA is aimed at only providing a straightforward test of the board to reveal manufacturing defects.

As the majority of manufacturing defects are simple connectivity issues, the MDA is restricted to making measurements of continuity. This significantly reduces its cost making it more viable in many areas of test.

MDA basics

The concept for the MDA is based around the concept that the design of a board has been previously proven, and parts are reliable and very few defective components will be delivered. Therefore it should only be manufacturing defects that will impact the performance of a board or assembly. As most of the defects consist if solder splashes and poor or open joints, then the majority of failures will be detected by testing for a relatively simple spectrum of failure types.

While Manufacturing Defect Analysers are primarily focussed on the detection of the very basic faults, even the most basic testers these days will also detect missing components, although the exact functionality for any given MDA will only be revealed in the datasheet / specification. Often the tester will be able to detect the presence of resistors, capacitors and transistors. The detection of integrated circuits can also be achieved using the protection diodes to indicate whether the component is correctly placed.

The tester makes connection to the board under test using a bed of nails fixture, and this means that a different fixture is generally required for each board. It needs to make contact with specific points on the board, where often there may be a test point or land area for the probe.

Like other forms of In-Circuit Tester, an MDA will use the printed circuit board CAD data for the generation of the fixture design and the test programme. This often allows up to around 80% of the test programme to be generated automatically.

MDA Advantages / Disadvantages

Like any other technology the manufacturing defect analyser has its advantages and disadvantages. These need to be considered when choosing which type of tester and test technology should be used.

Advantages & disadvantages of a Manufacturing Defect Analyzer, MDA
Advantages	Disadvantages
Machine is much less costly than a full ICT Can detect open and short circuits which form the major number of defects Can detect some values dependent upon the MDA capability	Limited component diagnostics Still requires bed of nails fixture and its associated costs Component access can be an issue with current board density levels

An MDA machine is very much simpler than a full ICT. This makes it an attractive proposition for many situations, particularly within smaller companies where the capital expenditure investment of a full ICT machine may not be viable.

In many other situations a Manufacturing Defect Analyser may be a viable option is where the fault spectrum does not warrant a full In-Circuit test. This decision can only be made in the light of an analysis of existing fault spectra for a given manufacturing line.