Model 2212 System protectively sealed. These are standard process steps in hybrid
IC manufacturing. Crystal Mounting, the previously tested and qualified crystal
needs to be mounted to the assembly. Testing and compensation The steps described here are for the PRA Model 2212 System
configured for TCXO production. The Test Cards will hold the
oscillator, making the needed contacts to the PROM writing/
control circuits as well as the oscillators, Vcontrol, Supply,
Ground and output contact. The steps to use this system are: • Load Pallet/Test Card with the TCXO assemblies.
Depending on packaging the number units would be 256 per
test card (5x7 and 9x14 SMD parts will number 256) • Go to a PC on a LAN with the Model 2212 system and tell
the computer the target frequency and specification for the
oscillators loaded in the Test Card. Each Test Card has a
unique serial number. Place the Pallet/Test Card assembly in
a queue waiting for testing time in the chamber. • When space is available in the chamber load up to three Test
Cards. The systems does permit mixed frequencies and
temperature ranges. (NOTE: Mixing temperature ranges can
lengthen the testing time, yet still being more efficient than
making multiple separate tests.) • Press the Start Button on the chamber front after closing the
chamber door and the testing begins automatically. The prior
entered information about each Test Card is found over the
LAN and the assigned tests are started. • During testing, the PC’s monitor shows the status of run, no
operator interventions is needed. • At the completion of the run the measured data is analyzed
and the Test Card may be removed from the chamber, this
makes the chamber immediately available to start another
group of devices. • Go to a PC on the LAN and display or print the location of
the good devices for each Test Card/Pallet. The testing time for 768 parts for a -20oC to 70oC
compensation will be typically 3.5 hours or less than 17
seconds per oscillator. This is the total time for compensation,
programming and final testing. (Based on cryogenic gas
cooling, compressor cooling will add about 1 hour to the
process). What occurs during temperature testing (the Test
Card/Pallet assemblies remain in the chamber during these
steps)? 1) Precompensation testing over the temperature range- At each temperature the IC for each TCXO is exercised for the
ICs function on the crystal. The PROM circuits are "soft"
programmed and the TCXO’s performance is logged. Each
TCXO circuit and the crystal are analyzed together. 2) Compensation- The parameters from step 1) are analyzed and the best programming conditions are determined for the
PROM. (Remember all these conditions have already been
logged, so when programming is done we can be very confident
that the TCXO will perform the best compensation possible.) 3) Chamber returns to about room temperature for proper PROM programming while the compensation computations
are completed. 4) Programming- Each TCXO that will meet specification has its PROM permanently programmed. 5) The Test Card /Pallet are testedover temperature to verify proper operation. The actual precompensation, compensation, programming
and final test, all are essentially one process step in the
manufacturing area. Marking and shipping, the good units are now ready to be
marked and shipped. Failed oscillators may be passed through the Testing and
Compensation step one additional time. This would assure that
the first failure was not due to contact or fixturing issues. After
the second failure, the assembly may be salvaged but there are
not steps to recover the unit. PRA compensation technique
exhausted all the possible compensation options and additional
testing will not improve the compensation. NOTE: PRA Inc. reserves the right to make changes to the product contained in this data sheet in order to improve the design or performance
and to supply the best possible product. PRA Inc. reserves the right to make these changes without notice. Revised 9/1/02
Digitally Programmed Analog TCXOs This configuration can be one or two chambers per computer.
The minimum configuration per chamber is 1 each Counter
and 1 each DMM. The fastest configuration per chamber (this
is the times PRA supplied examples for) is 3 each Counters and
3 each DMMs per chamber. Manufacturing Steps to Make Digitally Programmed Analog Compensated TCXOs There are four companies now making circuits that permit making TCXOs that require no component adjusting during the compensation steps. These circuits use analog internal
switches that are set by a PROM to output the proper
compensation voltage to the varactor that controls the crystal
frequency. This is the classic Indirect Compensated TCXO
circuit with the proper component values set by a PROM. The four companies have very similar solutions for the TCXO
circuit, the key difference is the PROM used by each is
significantly different.
•AKM, Japan The PROM is eePROM technology, moderate voltage and low programming current are required.
• Panasonic, Japan
The PROM is fusible link technology, low voltage and high
programming currents are required.
• Kawatetsu, Japan
The PROM is ePROM technology, high voltage and low
programming currents are required.
•MAS, Finland
The PROM is ePROM technology, high voltage and low
programming currents are required. Because of the dissimilarity of the programming
requirements, PRA supplies different test fixturing for each
IC manufacturers type of TCXO solution. The requirement of a TCXO requires very stable and spurious
free crystals. These newer integrated circuits do not lessen the
need for these conditions. The new integrated circuits do
permit wider angle spreads to be successfully compensated. Crystal Production: Only separately sealed crystals have proven to have good
enough aging to be used as TCXOs. Crystal sawing, lapping and polishing require quality control of the angle spread and the blank preparation must lead to spurious free crystals. Crystal platingmust be of the highest quality. TCXO require
excellent crystal aging characteristics. The platers and
vacuum systems must be carefully chosen and operated with good process control to be sure the crystals have these required
characteristics.
• Consistent motional parameters • Good angle control • Spurious free • Excellent aging Crystal Sealing, must be clean process that does not add to the
crystals aging process. Crystal Aging.
The crystals must be baked for a long enough period to be sure all the infantile aging is eliminated. Crystal should be checked on a PRA Model 2360
Aging System. At least on a lot sample basis and for the better
TCXOs, 100% of the crystals should be aged in this type of
system. Crystal Testing - Room Temperature
All crystals must be tested for motional parameters,
resistance and drive level dependency. This should be done
after the aging period. Crystal Testing - Usable Temperature Range
All of the crystals need to be tested over the temperature range to insure each unit is spurious free and to confirm the crystal
angle. Ideally the crystal will be tested at small temperature
steps, 1oC or less to be sure of no spurious responses. The PRA Model 2511 system provides a solution and provides
low cost per unit tested. This systems tests 1024 crystals per
run. The PRA Model 2212 with crystal test boards can test 1152
crystals per run. The system permits screening crystals for
angle and perturbations. The system can test 1152 every 0.5oC
from -40oC to +85oC in approximately 2 hours. Crystals that have met all of these testing steps are now
suitable for use in a TCXO. Oscillator Production: Successful TCXO production with high yields of
compensation mandates that the crystals must have excellent
aging. If the crystal change during these process steps, the
manufacturing yields will be poor and the end use rejects will
be high. Packaging, the IC, typically 2 or 3 capacitors, possibly a
varactor need to be assembled into the TCXO package. This
is typically a ceramic package with screened pattern to
accommodate these components. The IC needs to be die
attached to the package, then wire bonded and then
System Documentation and Options Temperature Chamber The system uses the PRA Model 66322 Multiplexer,
Power Supply and Temperature Chamber. The 66322 provides
the controlled temperature environment and well as the power
to the DUTs. This well integrated temperature chamber
enhances the speed of testing as all parts are optimized for the
testing to crystals and oscillators. PRA Inc. can supply a mechanical cooling
compressor assembly. PRA Inc. in cooperation with G. S.
Tech of Korea can supply a cascade compressor setup (this has PRA Inc. reserves the right to make changes at anytime to this specification without notice. PRA Inc. will supply the following information. Most of this information will be supplied on CD-ROM. For
example the manuals will be supplied in Adobe Acrobat® PDF
file form.
•All software source code. The code will be documented
liberally with comments.
•The description of the development environment used to
compile the software.
•All compiled operating programs. This information package is intended to be a
complete set of information needed to maintain the current
systems. The system documentation remains the property of
PRA Inc. and may not be distributed or sold by the system
owner to anyone without the permission of PRA Inc. The
system owner is free to use and copy this information for their
own internal use as needed. This information will be updated as additional
changes to the systems are made. When changes are made
PRA will supply an update via CD-ROM or via e-mail. Maintenance Test System This is an optional feature to assist in maintaining temperature test systems operating in a production area. The
maintenance system permits rapid validation of proper system
operations and assists in troubleshooting the test system. This is a PC and associated test equipment that
permits checking of the 2212 system for proper operation. There is a special test board that plugs into the chamber. All
test signals are monitored, voltages are checked, measure
nodes of the 2212 system have signals present to check
operation. The system will be mounted on a wheeled cart so the
system can be easily wheeled up to the chamber to service. The system owner can optionally supply their own
PC, DMM and wheeled test stand. Pre Test System This is an optional room temperature system that is essentially one test slot of the Model 66322 chamber. This is
used to check the parts prior to loading them in the chamber.
This system can perform all the same functions as the
complete system can except it can not set temperature. Load Station Simple PC that optionally can read the test board
serial numbers (electronic RS232 interface to the test boards).
Permits defining the needed information for a test board to be
tested in the system. Minimizes the time the system is idle
with operator input. Also, means the test system operators are not
required to perform any operation at the test system PC. already been accomplished on numerous PRA Model 66222
chambers). The cooling speeds are typically 5 to 6 times
slower than cryogenic cooling. Compressor cooling for
maximum load of OCXOs may not be practical, contact PRA
about this unique condition. The Model 66222 was derived from the very
successful Model 66222 chamber that has been in production
for over 3 years prior to the design of the Model 66322 Many
parts are interchangeable between the 66222 and the 66322. ASIC Test Board with support pallet. One of many options to hold DUTs.
Carrier pallet for array of ASIC TCXOs. The
array will be separated into individual TCXOs
later in the process. The carrier pallet will nest the individual TCXOs also. Test board for ASIC TCXOs. Contains the
needed multiplexers and buffer ICs to measure the customer specified nodes.
The test boards are slid in tracks into the chamber. These test
boards or cards have a microprocessor on each card, this
performs multiplexing and other measurement control. These
processors assist in special functions such as programming the
PROM controlled TCXOs. •Test Board size 304mm x 457mm (12" x 18") that can contain
the Devices Under Test (DUTs). •OCXO DUTs The test boards can hold up to 60 OCXO The total supply current per test board is 180 Amps • Simple oscillators The test board can hold
up to 384 5x7mm
oscillators • PROM programmed
TCXOs The test board can hold
256 AKM, Kawatetsu
or MAS oscillators.
Each type of IC does
require a specific test
board, because of
different programming
needs a common board
is not feasible. •Precompensation
TCXO DUTs The test boards can contain as many DUTs
that can be powered by the power supply and fit on the test board. The
addressing for a DUT is
a 20 bit address
(selection of 1 of
1,048,576). Measurements of internal oscillator nodes can be made. •Crystal Oscillator DUTs (VCXOs also) The control voltage function can be measured •Leaded DUTsplug into sockets on the test board. •SMT DUTscan be mounted in sockets or placed in pockets with pogo pin contacts and a single cover board to hold the
SMT parts in place. •DUT selectionis performed by a simple processor on each test board •The selection processor is accessed via a serial signal from the Measurement PC. •System provides various power sources to the test board to
power the DUTs and any measurement logic on the Test Card, all supplies are floating isolated supplies. •The test board has a single output coaxial connector that connects to any external instrumentation, for example an
oscilloscope. The bandwidth is greater than 2 GHz. •Connector: DIN 41612 3 x 32 in chamber center for general
testing. This would all that is needed for TCXO testing. •Connector: DIN 41612 3 x 32 in chamber left for
miscellaneous testing. This is will be used for the precision
Vcontrol (Vtune) needed for OCXO testing. •Connector: DIN 41612, located on the chamber right side,
will have an direct RF output and power for 60 OCXOs. Multiplexers and Carrier Plates Test board for OCXOs. Contains 60 DUTs and permits testing the electronics frequency adjust function
•Temperature or aging run begins
- measurements are made, immediate measurement data
being stored locally.
- at the conclusion of any measurement sequence the block of
data is transferred to the system server.
- status updates of the chamber to the system server are done
about once per minute if all is proceeding normally and
immediately when any not normal operation occurs. •Temperature or aging run ends
- final test data is written to the server.
- server status files are updated
- display on the oven indicates the run is done System Measurement software •user defines a temperature sequence that the chamber will
follow. There can be nearly unlimited points (limited to hard
disk drive file restrictions).
•Each DUT has a test specification that tells what
measurements to make, the temperature range and limit
(Pass/Fail) information. •Multiple types of DUTs can be mixed together in a test run.
The DUT is only read at temperatures that are within that
DUTs own temperature range. •The specification also sets the counter resolution, supply
voltages and any needed wait times. •All test data is stored in ASCII text files. •The types of measurements are determined by the Test Card
capabilities and the measurement equipment on the system. Typical measurements are:
-Frequency
-Current of the DUT
-VCO measurement of pull and sensitivity
-Uncompensated TCXO parameters such as voltage to put the
oscillator on frequency, sensitivity of the setting in ppm/V,
thermistors can be made.
-Voltages at user specified nodes
-If a digital oscilloscope is present and the test board has the
multiplex capabilities, waveform parameters such as rise
time, fall time, duty cycle, logic levels, pulse width, Peak to
Peal levels, RMS levels can be made. •Each DUT is stored in that DUTs own test file. Voltage Monitor Function: Voltages are output to the back panel where the system DMM
is used to monitor all chamber voltage functions. All power
supplies, DUT and control are monitored. Chamber Multiplexing, DUT data and Frequency
Measurements: All control and DUT selection signals are sent to the chamber
via the RS232 or RS485 connection. The worst case time for
a complex command send would be 5mS or less, this is deemed
a minimal time compared to the measurement and settling
time for very precise measurements. DUT Selection: DUT selection is performed by simple processors mounted on
the test boards. Position information is sent serially to the
chamber multiplexer, then buffered and then via the back
plane to the test board. Counter: The counter is a GPIB interfaced HP53132. The counter
requires a precision 10MHz external standard, the accuracy
of the counter is completely determined by the external
standard and the waveform quality from the oscillator to the
counters input. The multiplexer is capable of waveform
integrity to 0.0001ppm (0.1ppb). DUT Signal to the Counter: The signal to the counter is by a coaxial cable and is
terminated in 50ohm. The highest frequency from a test board
is 125MHz. For higher frequency appropriate prescaling will
be done on the test board. The signal will be prescaled to always be less than 50MHz. The DUTs will be nested in a pallet that mates to the
multiplexer and makes contact to the oscillators with pogo
pins. The assembly will plug into the center MUX control in
the chamber’s back. Measuring Oscillator Waveforms Any of the system configurations can have a digital scope added. This would permit measuring Tr, Tf, Vhigh, Vlow,
Duty Cycle, V PP, Vrms, overshoot, undershoot, pulse widths,
and with some restrictions jitter. The signals will be
electronically multiplexed. The current state of the art
permits a 750 to 900MHz electronic multiplexer for a
reasonable cost and sufficiently small so that an acceptable
number of units can be tested. Waveform capability can be
added to any of the systems and can be added at a later date
as a system upgrade. PRA suggests three scopes for this application:
-Tektronix TDS3052, 500MHz BW, low cost and no jitter
capability.
-Tektronix TDS724, 500MHz BW, improved accuracy and
jitter capability.
-Tektronix TDS784, 1GHz BW, improved accuracy and jitter
capability. Other Tektronix scopes may be used. There are special
techniques available for higher bandwidth needs.
System Features The PRA Model 2212 Oscillator Temperature Test System is
designed to measure various types of crystal oscillators. The chamber holds three each test boards. The test
board fixtures and holds the parts to be tested. The test boards
are intended to evolve for the various kinds of oscillators and
products to be measured. The intention is the test boards
provide the flexibility needed to permit longevity of this
testing system configuration. -A group of chambers is controlled from a single master
controller. The system is operated on an Ethernet LAN using
the MicroSoft™ Network. (This LAN can be part of the
company network, if the protocols are compatible and the user
deems the traffic is at an acceptable level.) The network cards
supplied will be 10/100baseT dual frequency compliant. The master controller position has the needed
hardware and fixturing that will accept a test
board and operate the test board at room
ambient. The full function master controller:
•User sets up measurement procedures.
•User connects the test board, indicates to the
PC the board is loaded. The PC then reads the
serial number and looks up the characteristics
of the test board (multiplexing, DUT position
names, typical supply limits, etc.)
•Test card is set up
-serial number of the card is read
-serial number of the DUTs are entered by the
user
-each oscillator position has the frequency read
and validated
-each oscillators test procedure will be user set
-test information and parameters are stored on
the test system’s network server.
•The user can monitor the status of any chamber
in the system at any time.
•The measurement data (completed or partial)
can be accessed at any time.
•All completed measurements will be
transferred to the master controller.
•Operating system Windows NT 2000 Professional •Programmed in MicroSoftTMC, MicroSoftTM
Visual BASIC for Windows and DOS. The master controller - reduced function: In the case were only one Model 66322 chamber is
used, the PC on the chamber or any PC on a network could be
used as a master controller. This controller would not be able
to pretest the DUT test cards. Chamber controlling computer: •Controls the chamber via a COM port
•Controls each test card via a COM port
•Interfaces the system’s master controller via the MicroSoft™
Network LAN connection.
•Stores the most recent test data on the hard disk.
•Operating system, Windows NT 2000 Pro
•Programmed in MicroSoft™ C, MicroSoft™ Visual BASIC
for Windows. Typical sequence to operate a chamber (System has simplified this step to minimize the skills needed by
production operators.
• Test cards are put into the test chamber
• The door is closed and checked by the controller
• The operator presses the "Start" button on the front panel of the chamber. The next steps occur automatically.
• The chamber controlling computer checks the test board
serial number and then checks the master controller and
determines if the test board has been set up to be tested.
• The parts in the test board are checked to make sure the same
measurements occur that were read at the system control position.
Model 2212
Oscillator and Crystal
High Speed Fully Integrated
Temperature Test System Features: • Smart test cards to perform
ASIC TCXO compensation and
programming. • Option testing of high current OCXOs • DUT measurements to 1 GHz: Supply current
Frequency
Pullability • Permits fast crystal screening
for perturbations and angle • Electronic multiplexer of the
DUT signals. • Optional waveform
measurements to over 1 GHz • Holds DUTs in a rectangular
array pallet ideally holding
SMD units • Leaded parts are plugged
into sockets • CO2, LN2 or compressor
cooled • Special air flow control to each pallet for excellent
uniformity System shown on optional racks with one chamber having OCXO power supplies
