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TEST PROGRAMMING, GENERAL

The following information applies to many or all of the individual tests described in this section of the manual.

Each test description line begins with TEST followed by a sequence number in the range 1-75. A space between TEST and the number is optional. TEST2 is ok, so is TEST 2, or TEST 2. Extra spaces are ignored. On the following pages we often refer to TESTn where n is the sequence number you will fill in.

You can write the tests in any convenient order. MAXX will sort them into order by sequence number.

Tests are by default performed in order of the sequence numbers but conditional or unconditional jumps may alter the sequence. You can leave some test numbers unused if you wish. In fact it may be helpful to do so since you can fill in new tests later between existing tests.

The next item to be entered is the test name, IR, VZ, VF for example.

Next, most tests will require one or two forcing conditions. Although there are some tests (SLAVE for example) that require none. When two forcing conditions are required, the order of entry may be important. Such information is always mentioned in the description of the individual test later in this manual.

MAXX will adjust the decimal point for you. For example, if you enter IR 1V, MAXX will adjust this to 1.000V. If the value you enter is not valid for the particular test, you will get an error message and the test will not be accepted.

If you do get an error message after you have entered a whole line of text describing a test, you can save a lot of typing by pressing the <F3> key. This will return the rejected line so that you can correct it.

Next you enter test limits and/or scale selection information. The minimum and maximum limits and scale selection number may be entered in any convenient order. You may enter up to three numbers here but only one is required. MAXX will choose the most sensitive readout scale that will contain the highest number that you enter. The following example should make this clearer.

You enter TEST1 VZ 10MA 25V >12V <15V

When you list the program, you will see

TEST1 VZ 10.00MA 25.00V >12.00V <15.00V

The 25V that you entered forces MAXX to use a higher scale. If you are data-logging, you may want to read parts even though they are above the high limit. If you don’t need readings on these parts you can leave out the 25V and you will get this:

TEST1 VZ 10.00MA >12.000V <15.000V

You don’t need to enter double-ended limits if you don’t need them. In fact you don’t need limits at all if you just want readings. But in this case you must enter a number to tell MAXX what is the largest reading you expect. (Such as the 25V above).

After the limits you can enter a number of optional parameters in any convenient order. The general purpose parameters are described here but you will find a few more in the descriptions of the tests that use them.

SOAK TIME

Soak time is the time in milliseconds that MAXX allows the part to sit at the forcing condition before taking a reading. In some cases additional time is allowed (not included in soak time) for the forcing condition to “ramp up”. For each test MAXX has a default soak time which we consider to be the minimum appropriate for that test. In most cases you will just use the default although you may occasionally want to increase it. To set the soak time add a T followed by a number of milliseconds.

For example: TESTn IR 10V <2NA T50

If you enter a number outside the valid range you will get an error message which will tell you what the valid range is. Incidently, this is a way to find out what the default is. The default value is the lowest valid number.

ORIENTATION

If you add F1 to a test, the orientation of the part being tested will be reversed BEFORE doing the current test. It will remain in this state unless reversed again by another F1. You can use this to test both sides of a bipolar part or to use the VF test to measure VZ at low voltages or perhaps for other reasons.

F is a general purpose function that depends on the following code number. For example F2 is another function related to IR tests. You may want to use both functions on the same test. If so add the two codes together and use F3.

JUMPS

You can program both conditional and unconditional JUMPS to control the program flow. These jumps can be expressed in absolute or relative terms. For example

TEST3 VZ 1MA >15V JF10 or TEST3 VZ 1MA >15V JF+7

Both examples will cause a jump to test 10 if test 3 fails.

You can also jump on pass “JP” or unconditional “JU”. Backward jumps such as JF-3 are ok too, but watch out for endless loops.

PSEUDO-TESTS

There are a number of tests that don’t actually measure anything. They may do math on the results of other tests, or add additional test limits, add delays, or a number of other things. All of these are listed later in this section along with the other tests.

EDIT EXISTING TESTS

You can call back an existing test for editing with the ET command.

ET3 brings back existing test 3 so that you can edit it. This is a very useful feature since it is much easier to edit an existing program than to write one from scratch.

Also, don’t forget <F3>. If you enter a line (a test or any other line) and then you want to change it, just press <F3>.

WRITE OR EDIT A PROGRAM

This section deals with standard test PROGRAMS written or edited using MAXX USER INTERFACE. There are some other special purpose types of programs, and standard PROGRAMS can be written off-line ASCII. These subjects are covered elsewhere in the manual.

A NEW PROGRAM

If you will write a completely new program from SCRatch, first enter the command SCR to erase the PROGRAM 0 buffer.

EDIT AN OLD LINE

LOAD an existing program, edit it and then save with a new filename. Since few programs are completely new, this usually saves a lot of time. It is very helpful to have a printed copy of the old program for reference.

SAVE TO DISK

RECORD <filename> will save your new or edited program as a standard FEC PROGRAM in the directory \MAXX\PROGRAMS. If you use an existing filename MAXX will ask your permission before over-writing the original.

PASSWORDS?

The use of PASSWORDS is optional but MAXX does support the use of PASSWORDS to allow users to JOIN edited programs to test stations or to save them to disk.

WHAT IS A PROGRAM?

A PROGRAM in MAXX is a collection of instructions to the tester for testing and sorting diodes into BINS. This program also inherently produces a set of READINGS.

The major parts of a PROGRAM are listed below:

WHAT IS A PSEUDO-TEST?

PSEUDO-TESTS, unlike regular test don't actually cause the hardware to measure anything. They may calculate their readings from data already at hand or in some cases may not produce any readings at all, but may control program flow or simply compare existing readings with new limits. Even though they don't measure anything, these tests are very useful and give MAXX some of its most powerful capabilities.

TEST FORMAT

Both TESTS and PSEUDO-TESTS are written in the same format.

Here is a typical test (a simple one):
TEST 1 VF 1A <1V

Every test starts with the word TEST and a number from 1 to the maximum number of tests allowed.

Next enter the name of the type of test from a list of available tests.

0 to 2 test conditions follow as required by the type of test. (For example 1A <1V as shown above).

Minimum and maximum test limits may be added for most tests but are not required, although in many cases you may have to enter an expected maximum reading so that MAXX can select an appropriate readout scale.

The above may seem a bit loose, but actually you must consult the list of available tests to see what parameters are required for each type of test. MAXX will complain if you don’t enter the appropriate data. Here is a more complex example:

TEST 3 DELVZ 1MA 10MA 10V <.1V T50 F1 JF10

DELVZ measures the difference in VZ between 2 currents. The 10V tells MAXX what maximum VZ is expected. T50 means the “SOAK TIME” will be 50mS. F1 means flip the orientation of the part before measuring it. JF10 means jump to TEST 10 if this test fails. Otherwise TEST 4 would be next.

Don’t worry, all of these details will be more fully covered later, most of them in the AVAILABLE TESTS section.

Here is a PSEUDO-TEST:

TEST 4 MP T50

MP means Must Pass. This test doesn’t do much except “pass” when it is encountered in the program flow. Options like the T50 to add a 50mS delay do work though. There are more good uses for this than you might imagine.

ABOUT THE LIST OF TESTS

Unused test are performed in test number order, but you can change the order with conditional or unconditional jumps. You can even perform one or more tests multiple times using the PSEUDO-TEST LOOP.

ORDER OF ENTRY OF TEST

It doesn’t matter at all in what order you enter the tests (or anything else in the program). Just get it all in and MAXX will sort it out.

WATCH OUT!

The above refers to the order of entry of the lines of the program, not to the order of items on a line.

BIN SORT LIST

BIN 1 is assumed to be the most desirable one. Therefore if a part can pass BIN 1 it won’t be considered for any other BIN. You can start an elimination process beginning at BIN 1.

Enter BIN 1 and a list of the test numbers that must pass to have a good BIN 1. You can also add a BIN TITLE of up to 16 characters. Also see the list of SYMBOLIC TEST NUMBERS for use with certain built-in tests.

When you program BIN 2 you can assume that some requirement of BIN 1 must have already failed (else why isn’t it in BIN 1?).

Consider the program fragment below:
BIN 10 REJECTS NOSHORTS NOOPENS
BIN 11 SHORTS NOOPENS

BIN 10 has no requirements other than no shorts or opens, so if it fails BIN 10, it must be one or the other.

So if BIN 11 has no opens, it must contain shorts.

MISCELLANEOUS SORTING CONSIDERATIONS

SHORTCUTS

If you enter a long line and MAXX rejects it because of a syntax or other error, you don’t need to retype the whole line. Just press the <F3> key and the line will be returned for editing.

You can edit an existing test by entering Etn where n is the number of the test. Keep in mind that you can edit the test number to get a new copy of the test while keeping the original.

MAXX will allow you to leave out spaces in many cases, and insignificant trailing zeroes in all cases. The output will be formatted neatly when it is listed in any event.

The following two lines will both work.

TEST 1 VZ 10.00MA >6.000V <7.000V
TEST 1 VZ 10MA >6V <7V

The following editing keys can be used when entering or editing a line in MAXX: Right and left arrows, Space and Backspace, End and Home, Del and Insert, Tab and Shift Tab, <Ctrl>Del.

TESTING CAPACITANCE WITH AN FEC200

When testing Capacitance, the FEC200 tester makes use of the fundamental relationship between charging current and rate of voltage change.

The formula is: Volts/Second = Amps/Farads

A practical example: If the rate of voltage is 1V/mS then a 1F Capacitor would charge at 5A. On this scale the resolution of the tester is 0.02pF.

The FEC200 can produce accurate linear ramps at various rates and can measure charging current accurately. The charging current is sampled just before the top of the ramp and the voltage at that point is programmable.

If the ramp rate goes to zero the charging current is an ideal Capacitor should immediately go to zero also. If the current is sampled soon after the ramp stops, any remaining charging current is a measure of Dielectric Adsorption. The Dielectric Adsorption of most dielectrics has a long time constant it is usually impractical to wait long enough for that effect to completely subside. A compromise must be made between accuracy of the leakage resistance test and reasonable testing rate. The FEC200 can be programmed for long test times if desired for correlation checks.

OTHER TESTS

Since the FEC200 is a general purpose tester with very powerful programming software it can be programmed to do other testing tasks such as checking the resistance of conductive stripes or the leakage or breakdown voltage between multiple Capacitors in a module.

OTHER FEATURES

The MAXX testing software and the STATS statistical software supplied with the tester can collect and report statistics on the components being tested. It can also produce reports of the changes in component’s characteristics before and after environmental tests or burn-ins. It can compare the changes with limits to reject parts whose changes are excessive.

ABOUT THE “F” OPTIONS IN MAXX

MAXX sets aside 8 bits in each stored TEST to control miscellaneous options. This section explains the current applications of these “F” options. It is possible that there will be additional controls added in the future.

You can add an “F” option anywhere on the test description line after the test limits. The syntax is Fn where n is a number from 1 to 255. 31 is the highest number that uses the current options.

If you wish to program two or more options on the same test, just add their option numbers together. For example to reverse the orientation of the diode (F1) and remove the IR limiting resistor (F2) just use F3.

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Last Updated September 12, 2007
Copyright 1997, 2006