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ICT (In circuit testing):

ICT (In circuit testing) A part of BTS manufacturing ……

OLD MANUFACTURING TECHNIQUE:

OLD MANUFACTURING TECHNIQUE 1. COMPONENT INSERSION 2. SOLDERING 3.VISUAL INSPECTION 4. FINAL ASSEMBLY 5. FUNCTIONAL TESTING 6. SYSTEM TESTING

NEW TECHNIQUE:

NEW TECHNIQUE 1. INSERSION OF COMPONENTS 2. SOLDERING 3. VISUAL INSPECTION 4. IN CIRCUIT TESTING 5. FINAL ASSEMBLY 6. FUNCTIONAL TESTING 7. SYSTEM TESTING

Slide 4:

Inside BTS

Cards used in BTS:

Cards used in BTS BTS……………

What a ICT is …..:

What a ICT is ….. In-circuit test (ICT) is test technique , where an electrical probe tests a populated printed circuit board (PCB), checking for shorts, opens, resistance, capacitance, and other basic devices which will show whether the assembly was correctly fabricated.

Basics of ICT….:

Basics of ICT…. In-circuit test equipment consists of two main parts. The first is the tester itself This consists of a matrix of drivers and sensors that are used to set up and perform the measurements. Second part of the tester - the fixture. Acts as an interface between the board and the in circuit tester.

CARDS USED IN TESTER :

CARDS USED IN TESTER SMALL CARDS PINBOARDS CONTROLLER BOARDS

ICT fixtures and connections…. :

ICT fixtures and connections…. In order to carry out the test it is necessary to gain access to each node on the board. The most common way of achieving this is to generate a "bed of nails" fixture. The board is held in place accurately by the fixture and pulled onto spring loaded pins that make contact with connections on the board.

Guarding :

Guarding The key to the success of in-circuit testing is a technique known as guarding. It is very easy to measure the value of a component when it is not in a circuit. Here the nodes around the component under test are earthed and in this way any leakage paths are removed and more accurate measurements made.

Fault coverage :

Fault coverage With access to all the nodes on the board, manufacturers generally quote that it is possible to find around 98% of faults using in circuit test. Low value capacitors are a particular problem as the spurious capacitance of the test system itself means that low values of capacitance cannot be measured accurately if at all. A similar problem exists for inductors but at least it is possible if a component is in place by the fact that it exhibits a low resistance.

Test sequence :

Test sequence Discharging electrolytic capacitors. Shorts testing Analog tests Opens Express Powered analog Powered digital JTAG Boundary scan tests Flash and other device programming

BOUNDARY SCAN:

BOUNDARY SCAN It is the method for testing interconnects It is defined by IEEE-1149.1 STANDARD It mainly provides 5 abbreviations TCK TMS TDI TD0 TRST

Limitations of ICT:

Limitations of ICT The quality of the test depends on quality of test probes (pins). The quality of electrical contacts can not be tested . If no test access has been provided by the PCB designer then some tests will not be possible.

ADVANCEMENT IN ICT:

ADVANCEMENT IN ICT FIXTURELESS testers AOI (automatic optical inspection)