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PCB assembly function test after generally called FVT ( 功能验证测试

by:Rigao      2020-04-01
This function will test the machine appearance as the product size, shape, and may have change, functional test way also can depending on the urgency of time, the number of test board, and the cost and have different choices. All I know is probably can be divided into the following several most common ways of functional test. Circuit board machine solid plug function test: usually a whole products inside are made up by more than a piece of circuit board, the so-called solid plug is to assemble a machine need to use all of the circuit board, parts assembled actually, but don't need to put into the cabinet, because want to test the function of the circuit board, so convenient dismounting must make circuit boards. As for solid plug to what extent will depending on which function test that, ideally, of course, is to can test all the function, if not, also want to can test most of the functions, the focus should be to can catch major issues, such as plug can start, key function is normal, and have a normal screen, otherwise it's meaningless to test, simply all the engine test again. In addition, also need to prepare before start testing as a function of the normal circuit board to the standard model ( 标准样品) , assume that A set of boards have A, B, C three board, when to test A board, just take out your B and C standard sample when fixture, replace only A board to do the test, to take turns to complete three piece of board test. The biggest problem of this test method is easy to damage the standard template ( 标准样品) Because some coupling between the circuit board and circuit board or flat cable plug is unable to withstand too many times, so generally will use extended wiring, good is to extend wiring can be convenient to assemble, not let all the boards all crowded together, in addition to extend wiring is cheap and easy to change, by changing a broken, more cost-effective than with bad piece of circuit board. But some of the function of the components of the signal with special needs, can't use extended connection, such as a bar code scanner ( 条形码) And touch screen, etc. Need to spend a lot of time ( 劳动) Also is the shortcoming of this method of testing, so this method is usually only used as EVT ( 工程师验证测试) Stage, production quantity is less, or before the circuit board design is not yet finalized. Functional testing machine needle bed: this method is to use the circuit boards stay ahead ( layout) The test point ( 测试点) And then use the probe ( 针) To guide sign up to do a complete functional test. The test of time as long as put the board in the testing machine, and then took a probe head after mechanical action comes into contact with the measuring point of the board under test, so you can put the board under test simulation to link the appearance of the whole machine, the last on the machine operation test all function is ok. If the machine is a product of screen and buttons, it will take these components of the signal are derivation, with convenient for the board under the instruction and view the results; If the product has no screen and buttons, then through additional transport interface is connected to the computer to operate and view the results of the tests. When making the functional testing of the machine, usually need to have a have to determine the functional testing of the complete machine, fixture manufacturers association spin-off products parts installed to the test fixture, welding on the other side and then connect the probe with a head of flat cable way to connect to the individual boards, probe largely supplant the machine when the connections between each circuit board on the coupling and the flat cable, so as to achieve rapid up and down ( 装载/卸载) The purpose of the board under test, and use fixture and less damage to the standard model, often don't have to change the standard model. Wireless needle bed functional testing machine: the functional testing machine the original needle bed testing machine is improved, it connects originally the wire behind the test probe cancelled, instead use a customized piece of circuit board to replace, only one that is originally probe head contact with under test board, now becomes a probe on the two ends are in contact with the circuit board, just as a contact on the board under test, while the other end contact on the customization of the circuit board. This circuit board can be in accordance with the need to run the line, and then connect to other circuits of the engine, can also switch to other mode of connection between the circuit board design, achieve certainly combination of products, and similar to the Big board, it helps to solve some problems to the operation of the signal interference especially sensitive components, because the line running on the circuit board, so I can make some interference between the ground plane to isolate the line of large area; And maintenance is easy, because there is no too much complex flat cable, don't need one flat cable for down, or are worried about the welding wire is broken. Defect is high fees, because of the need to make customization of the board, so the wireless function test fixture cost will be higher than the general function of needle bed test fixture is about 40% ~ 70%, and only for mass production and stable products, because as long as there is no circuit board design changes shifted to the test point, must be renewed his visit to the system of the circuit board.
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