February, 2016
www.us-tech.com
Page 59 Improving Traditional Test Methods P
rocess inspections, including solder paste inspection (SPI), automated optical inspection
(AOI), and X-ray, are able to detect most assembly errors — but others may lurk under the surface. SPI detects if solder paste is missing on certain pads, AOI is capable of iden- tifying missing, misaligned, or wrong components; and yet the board may still have invisible problems. Detection of the remaining pos-
sible problems requires electrical testing of the PCB. This sort of test- ing is not to discover errors in board operation. That would require para- metric or specification testing. A sim- ple test, independent of the function- ality of the PCB, is sufficient to detect assembly errors. For testing large volumes of production, an in-circuit tester, man-
The inability of assembly and functional testing to cope with today’s PCBs leads to long rework and repair times, and expen- sive bone piles.
ufacturing defects analyzer, or flying probe tester is used. These systems rely on access to nodes on the PCB through pins or needles. For lower production volumes, testing with these machines is much more expen- sive due to the cost of the test sys- tem and any additional fixtures. For smaller volumes of production a functional circuit test is often used.
enables automated diagnostics. This helps to reduce the cost of test devel-
opment and can shorten repair times. Combining the company’s
solutions with traditional testing results in higher test coverage for all types of boards. JTAG Technologies, cooperates
closely with well-known ATE compa- nies to improve the quality of test equipment. The company has devel- oped special versions of its hardware and software with test vendors to allow for smooth integration of its
tools into the various test systems. Contact: JTAG Technologies,
JT 37 x 7 RMI (rack-mountable instrument).
Inc., 111 N West Street, Suite A, Easton, MD 21601 % 410-770-4415 fax: 410-770-4774 E-mail:
info@jtag.com Web:
www.jtag.com r
JT 37 x 7 DataBlaster card for digital test.
The use of surface-mount devi -
ces, in particular ball grid arrays, makes the test system’s job of getting physical access to the PCB compli- cated and challenging. As a result, the fault coverage of these tests, and the quality of the end product, is re - duced. At the same time, the com- plexity of digital devices is growing continually. For example, today’s system-
on-chip devices contain the logic that used to require one or more boards. This ever increasing complexity and miniaturization make functional tests difficult, and in-crease the cost of development. The inability of assembly and functional testing to cope with today’s PCBs leads to long rework and repair times, and expen- sive bone piles. In both cases, JTAG boundary-
scan is a valuable addition to the MFT (manufacture-for-test) realm. The company’s devices can help restore the fault coverage to in-cir- cuit, manufacturing defects, and fly- ing probe testers. In functional tests, JTAG tools can simplify access to, and control of, device pins, which
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