Test container inst. 113



Rev. |ECO |Description |Checked |Approval |Date | |01 |50-021 |Initial Release |M. Smith | | | |

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Procedure for Picture

Focal Plane Assembly

50-06001.01

Revision 01

7/14/05

[pic]

1/3/2003 ADP

Assemble Focal Plane Array

Materials:

• Bench ionizer

• Wrist strap

• 100% Nitrile, powder free Anti-Static gloves

• Sheldahl Aluminaized Kapton tape, P/N G401000

• X-Acto knife with #11 blade

• Hysol EA 9394 adhesive

• GE RTV 566

• Ablestik ECF-550 adhesive sheet

• Dow Corning Silane Z-6032

• Panduit cable ties, PLTIM-M76

• Amp connector P/N 311P409-1P-B-12

• Heatsink/TEC assembly B458993

• Detector assembly D458992

• Standoff C458995-3

• Connector bracket B458995-2

• Minco RTD P/N S651PDX24A

• Torlon washer B458995-5

• Amp jackpost assembly P/N M24308/26-1

• Blank alumina substrate P/N 458990

• Standoff Collars P/N 458995-7, 458995-8, 458995-9

CAUTION:

A WRIST STRAP MUST BE WORN WHENEVER A DETECTOR IS BEING HANDLED OR IS MATED TO A PART BEING HANDLED. THE WORK SHOULD BE PERFORMED IN FRONT OF A BENCH IONIZER WHENEVER POSSIBLE.

PREPARE HEATSINK AND TEC

______ _____ Record the serial number of the TEC and the heatsink assembly:

TEC Serial Number: __________

Heatsink Serial Number: _________

Detector S/N: ___________

______ _____ Form the leads exiting the TEC at the point that they enter the wire guide slot. Use a pair of rounded nose pliers to hold the wire lead exiting the TEC so that the solder joint to the TEC is not unduly stressed during this lead forming operation.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Secure the TEC wires in place with a small dab of epoxy where the black wire first touches the heatsink and a small dab worked down into the slot where the wires enter the slot. Be sure that the staking material will not interfere with the collar that will be mounted in this area soon.

______ _____ Allow to cure for a minimum of 18 hours at room temperature.

______ _____ Mask off the TEC to prevent contamination during the addition of tapped holes.

______ _____ Add the nine 4-40 tapped holes (if not already installed) for the collar mounting.

______ _____ Tap the nine 4-40 holes required for the collar mounting.

______ _____ Remove masking materials.

PREPARE THERMAL STANDOFFS

______ _____ Measure the height of the top surface of the TEC relative to the heatsink surface that will receive the thermal standoffs. The thermal standoffs should be trimmed to be 0.006” shorter than the TEC/Heatsink height.

TEC height above heatsink = _________

0.006”

Calculated length of standoffs = ________

______ _____ Have three of the standoffs (C458995-3) machined to the appropriate length. The machining must be done either dry or using alcohol or water. No machining oils are allowed. The length tolerance is +/- 0.001”.

______ _____ Verify that there are no burrs on the top face of the standoff.

______ _____ Measure the length of each standoff using a height gage, electronic gage head, and surface plate. Rework or replace any piece that is not within the specified +/-0.001” tolerance. An easy and accurate way to do this is to install the standoffs onto the alumina substrate, place it upside down on a surface plate, and measure from the alumina to the standoff flange. Limit standoff screw torque to 36 in-oz.

Standoff #1 length = ________

Standoff #2 length = ________

Standoff #3 length = ________

______ _____ Wipe down the standoffs with a 2-propoanl moistened clean room cloth.

______ _____ Use the vapor degreaser in room I-209 with a minimum of 2 cycles through the vapor.

______ _____ Ultrasonic clean for 5 minutes in a 2-propanol bath.

______ _____ Very lightly dress the flange end of the standoff on 600 grit sandpaper supported on a surface plate.

______ _____ Wipe down the flange end of the standoff with a 2-propoanl moistened clean room cloth.

______ _____ Use the vapor degreaser in room I-209 with a minimum of 2 cycles through the vapor.

______ _____ Ultrasonic clean for 5 minutes in a 2-propanol bath.

______ _____ Dry the standoffs for 1 hour at 100°C in the class 100 drying oven.

INSTALL HEATSINK’S RTD, WIRE TEC, and RTD

______ _____ Clean the area where the RTD is to be installed by wiping with cotton swabs moistened with alcohol. Abrade the area with 600 grit wet or dry sandpaper. Rewipe the area with cotton swabs moistened with alcohol to remove particulate.

______ _____ Mask off the area where the RTD is to be mounted using 3M ESD tape. Leave approximately 0.030” clearance around perimeter. Locate RTD per drawing S458995.

______ _____ Clean the RTD mounting surface of the RTD (Minco P/N S651PDX24A) by wiping with cotton swabs moistened with alcohol.

______ _____ Locate two pieces of 0.006” diameter across the bond area (transverse to the lead wires) and secure with 3M ESD tape.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Apply a thin layer of adhesive to the heatsink and work it into the surface. Do the same on the mounting surface of the RTD. Verify that there is a small amount of squeeze out when the RTD is pressed into place with a cotton tipped swab. Wipe up excess squeeze out.

______ _____ Secure the RTD with a piece of 3M ESD tape.

______ _____ Form the leads exiting the RTD per drawing LL S-458995.

______ _____ Place a 2 in3 steel weight on top of the RTD to ensure it is registered against the 0.006” diameter wires.

______ _____ Stake the wires exiting the RTD to the heatsink approximately 3/8” from the RTD.

______ _____ Allow to cure for a minimum of 18 hours at room temperature.

______ _____ Remove weight and tape. Trim 0.006” diameter wires flush with the edges of the RTD with an X-Acto knife.

______ _____ Install the connector plate (B458995-2) using 2 4-40 x 5/16” screws. Torque to 8 in-lbs.

______ _____ Install subminiature D style connector (Amp connector P/N 311P409-1P-B-12) using two jackpost assemblies (Amp jackpost assembly P/N M24308/26-1). Torque to 48 in-oz.

______ _____ Form the leads service leads from the wires exiting the RTD per drawing LL S-458995. Tape in place.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Stake both ends of the RTD’s shrink tubing to the heatsink and run a second line of adhesive across the thin RTD leads near the point that they form a “U” turn.

______ _____ Allow to cure for a minimum of 18 hours at room temperature.

______ _____ Remove tape securing wires in place.

______ _____ Wire the TEC and RTD to the connector per CSR’s drawing 30-05021.03. The RTD leads require in-line splices to 24 AWG multistrand Teflon insulated wire per MIL-W-22759/11.

______ _____ Measure the TEC impedance using an HP impedance analyzer. The nominal impedance at 1 kHz is 10.7 Ω.

Measured TEC impedance: ________ Ω.

______ _____ Measure the resistance of the heastsink mounted RTD using a standard DVM. The nominal value at 70° F is 111 Ω.

Measured RTD resistance: ________ Ω.

______ _____ Secure the wires to the connector plate using two small Panduit 1/8” cable ties (PLTIM-M76). The locking feature should be on the top side (TEC side) to provide clearance with the flexprint rigid end.

______ _____ Measure the TEC impedance using an HP impedance analyzer. The nominal impedance at 100 kHz is 10.7 Ω.

Measured TEC impedance: ________ Ω.

______ _____ Measure the resistance of the heastsink mounted RTD using a standard DVM. The nominal value at 70° F is 111 Ω.

Measured RTD resistance: ________ Ω.

BOND STANDOFFS IN PLACE

______ _____ Use a blank alumina substrate (P/N 458990) as a fixture to locate the three standoffs. Mount the three prepared standoffs to the substrate using 2-56 x 5/16 screws. The screws should have a short length of shrink tubing installed over the shank to force the screws to be centered in the alumina’s holes. Set the clocking position of each of the standoffs per drawing 458995.

______ _____ Cut a small piece (1/2” x 2’) piece of 0.001” thick plastic shim stock and place on the bottom of the alumina in the area where the TEC will interface. Use tape to secure shim in place.

______ _____ Clean the three areas that will have standoffs bonded to them by wiping with cotton swabs moistened with Tricoethylene.

______ _____ Follow immediately with cotton swabs moistened with acetone.

______ _____ Follow immediately with a cotton swabs moistened with 2-Proponal.

______ _____ Blow dry with an ionized nitrogen gas blow off gun.

______ _____ Mix up a solution of acid to etch the bond areas. Mix 6.6 parts by weight (pbw) of sodium dichromate with 66 pbw of sulfuric acid with 100 pbw of DI H2O. Mix thoroughly then allow to cool to room temperature (about 1 hour).

______ _____ Make an acid brush from the selvage of some fiberglass cloth rolled up into a 3/8” diameter cylinder and held with a battery clip.

______ _____ Form a small puddle of the acid on the heatsink at each of the three locations where a standoff will be bonded. The etched area should be slightly (1/8” per side) larger than the bond area. Don’t make the puddle so large that it runs down the tapped holes.

______ _____ Allow the acid to sit undisturbed for 120 seconds.

______ _____ Rinse thoroughly with fresh DI water for a minimum of 1 minute. Use a strip of acid paper to determine the acidity of the effluent. Continue to rinse if acidity is less than pH 6.

______ _____ Perform a water break test on the three bond areas using DI water. Consult cognizant engineer if the part fails the water break test at any of the three bond areas.

Water break test results: _________________________ _____________________________________________ _____________________________________________

______ _____ Dry the part by wiping with a clean room cloth. Do not use line compressed air or bottled “air”. Both have significant chances of being contaminated, and we don’t want that, now do we?

______ _____ Mix a batch of Silane per Lincoln Laboratory PS-4-10, section 6.1.

______ _____ Apply a very thin coat of Silane in each of the three bond areas using an artist’s brush that has been cleaned in acetone and thoroughly dried. The swipes should start outside the bond area and end outside the bond area on the opposite side. If more than one pass is required to cover the complete area, minimal overlap should be used.

______ _____ Allow to dry for a minimum of 1 hour at room temperature.

______ _____ Place the heatsink in the class 100 drying oven in room I–209 with the oven powered down and at room temperature. Set temperature controller to 100 °C. Note the time that the oven reaches 100°C and leave the oven powered up for an additional 10 minutes. Open the door slightly and turn off the oven to allow the heatsink to slowly cool back down to room temperature.

______ _____ Install the detector alignment fixture (SK-ASE2-6) onto the heatsink supported on the assembly fixture (SK-ASE2-5)

______ _____ Install the alumina/standoffs onto the heatsink.

______ _____ Nominally there should be an 0.007” gap under each of the standoffs. Place a 0.006” diameter wire under each standoff and secure the wire in place with 3M ESD tape.

______ _____ Use an electronic gage head to verify that there is no tipping when the 0.001” shim is removed from the top of the TEC. Select larger or smaller wire diameter as required. The minimum allowable wire diameter is 0.005” and the maximum allowed is 0.010”.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Apply a small bead of EA 9394 adhesive to the base of each standoff using the handle of a cotton swab shaped into a flat blade.

______ _____ Verify that the 0.001” shim is still on the bottom of the alumina substrate. Locate the alumina/standoffs using the alignment fixture and allow the adhesive to transfer to the heatsink. Lift the alumina/standoffs off of the heatsink.

______ _____ Add or remove adhesive as necessary to result in a slight amount of squeeze out around the entire perimeter and full wetting of the standoff bond surface. Work the adhesive into the heatsink and standoff surfaces prior to the final iteration of adjusting the adhesive quantity.

______ _____ Once the adhesive quantity has been properly adjusted, install the alumina/standoffs and place a 2 cubic inch steel weight over the TEC to ensure that the alumina is firmly pressed against the shim on top of the TEC.

______ _____ Wipe the excessive squeeze out from around the bases of the standoffs using small polyethylene swabs.

______ _____ Allow the adhesive to cure for a minimum of 18 hours at room temperature.

______ _____ Remove the 0.001” shim, alignment fixture and tape from bond wires.

______ _____ Oven cure the assembly at 60°C for 1 hour. Load the part in the oven prior to powering up the oven. Start timing the bake once the oven gets up to 60°C.

______ _____ Cool the assembly in the oven by turning off the power to the oven, opening the door slightly and running the nitrogen purge at full scale.

______ _____ Place the heatsink/assembly stand on a leveling plate and level the top surface of the alumina.

______ _____ Remove the alumina from the standoffs.

______ _____ Measure the heights of the three standoffs relative to the top of the TEC by using a height gage and electronic gage head. Zero the instruments on the top of the TEC’s center.

Standoff #1 height = ________ (left of flexprint)

Standoff #2 height = ________ (right of flexprint)

Standoff #3 height = ________ (opposite flexprint)

______ _____ Install the three collars using NAS 1352C04-4 (4-40 x 1/4” SHCS) using the “peep holes” and the annular clearance between the thermal standoff and the central hole to align the collar to the standoff. Torque the screws to 10 in-lbs.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Load the epoxy into a syringe used with the Norlico 2000XL pneumatic dispenser. Attach a #18 hypodermic needle (green housing) to the syringe. Set the dispenser controls for 21 psi and continuous operation. The Maximum working time is approximately 45 minutes.

______ _____ Inject the epoxy into each of the injection holes with the hypodermic needle bottomed out against the top of the collar flange (to encourage circumferential flow) until the adhesive squeezes out between the standoff post and the collar central hole. When complete, there should be a continuous bead of adhesive around the standoff post. Continue to dispense glue as the needle is retracted from the injection hole to prevent sucking the glue out of the interior volumes.

______ _____ Wipe off excessive glue using clean room swabs.

______ _____ Stake collar screws.

______ _____ Allow adhesive to cure for 18 hours at room temperature.

______ _____ Apply a piece of low-e thermal tape applied around the body of each thermal standoff. Use the tape template (0.315” x 0.880”) to cut a piece of the low-e tape (Sheldahl P/N G401000). Use a sharp #11 blade in an X–Acto knife handle to cut the tape. Inspect the edge of the tape for any balled up adhesive and remove if found.

______ _____ Cut a vent hole in the low-e tape over each of the two vent holes on each standoff by poking with sharpened stick.

INSTALL DETECTOR

______ _____ Record the S/N of the device to be installed here and on the first page of this form.

Device S/N: _____________

______ _____ Verify that the RTV thickness will be correct with this detector substrate. Place a 0.0005” thick shim over the TEC and install the detector substrate with the three 2-56 x 5/16” long screws torqued to 36 in-oz. Each screw should have a Torlon washer (B458995-5). Verify that the shim readily slides out. Verify that a 0.002” thick shim can not be slid into the gap between the TEC and the detector substrate.

______ _____ Clean the area on the bottom side of the detector substrate that will be located above the TEC by wiping with separate cotton swabs moistened with Tricoethylene, acetone, and 2-Proponal.

______ _____ Clean the top of the TEC by wiping with separate cotton swabs moistened with Tricoethylene, acetone, and 2-Proponal.

______ _____ Install detector alignment fixture again.

______ _____ Mix a batch of GE RTV-566 using a pre-measured bi-pack.

______ _____ Spread a thin layer of RTV on the top of the TEC using a sharpened wooden handle from a cotton swab. Verify that the proper amount of RTV is present by installing the detector and torqueing the three mounting screws to 36 in-oz. Remove the detector and look for full wetting of the interface and not too much squeeze-out. Iterate as required. Once the correct amount is verified, add a small dab in the center of the TEC and install for the final time.

______ _____ Wipe off excessive RTV around the TEC top plate perimeter by using small polyethylene swabs. A small bead is acceptable if there is no chance that it will cause shorting of the TEC elements.

______ _____ Remove the detector installation fixture.

______ _____ Install the flexprint connector onto the connector plate using two 2-56 x 3/16” screws torqued to 48 in-oz

______ _____ Install flexprint thermal standoffs (C458995-3) using 2-56 x 5/8” screws and Torlon washers (B458995-5). Torque to 48 in-oz.

______ _____ Mix a batch of EA 9394 adhesive per manufacturer’s instructions (10 grams of Part A to 1.7 grams of part B).

______ _____ Stake the following hardware and features:

___ Top of standoff screws to detector substrate

___ Standoff to bottom of alumina substrate

___ Positronic to connector plate 2-56 screws

___ Connector plate to heatsink screws

___ RTD/TEC connector jackposts and nuts

___ Positronics to flexprint mounting hardware

___ Flexprint screws to flexprint cross bar

______ _____ Allow to cure for a minimum of 18 hours.

______ _____ Oven cure the assembly at 60°C for 1 hour. Load the part in the oven prior to powering up the oven. Start timing the bake once the oven gets up to 60°C.

______ _____ Cool the assembly in the oven by turning off the power to the oven, opening the door slightly and running the nitrogen purge at full scale.

______ _____ Photograph the top and bottom sides of the focal plane assembly. A label designating the heatsink and detector serial number should be in each photograph. Try to document the staking of each screw and the condition of each bond wire.

______ _____ Measure the resistances shown in the table below: Use test cable with a flight grade connector for probing the RTD/TEC connector.

|Pins |Nominal |Actual |

|5-9 |111 Ω | |

|4-8 |111 Ω | |

|4-5 |0 Ω | |

|8-9 |0 Ω | |

|1-6 |10.7* Ω | |

*Impedance at 1 kHz with HP Impedance Analyzer

______ _____ Use the class 100 nitrogen purged bake-out oven to bake the FPA at 60°C immediately prior to vacuum bake.

______ _____ Vacuum bake the focal plane array at 60°C for a minimum of 48 hours. Verify cleanliness with the TQCM and RGA.

Vacuum bake-out log number: __________

Sensor base S/N ________

Final total pressure ________ torr

______ _____ Inspect the sensor base and FPA under black light to verify that no loose particulate is present. Blow off with ionized N2 or vacuum off as appropriate.

______ _____ Install the connector savers to both fo the sensor base connectors. Torque screws to 48 in-oz.

______ _____ Verify that the detector harness has a shorting plug installed.

______ _____ Weigh the focal plane assembly while still on its handling fixture and with the shorting plug installed.

Weight of FPA _______ grams (with fixture and shorting plug).

Weight of fixture and shorting plug _______ grams

Weight of FPA _______ grams.

= ________ lbs

INSTALL HEATSINK INTO SENSOR BASE

______ _____ Scribe the centerlines of the two “Bonnet Pins” using a height gage fitted with a scribe marker.

______ _____ Scribe the radiation shield even with the frame store shield and 0.150” in from each edge using a height gage fitted with a scribe marker.

______ _____ Install the heatsink into the sensor base. Use 10-32 x 3/4” vented screws with washers. Torque to 34 in-lbs after the heatsink has been centered within the sensor base cavity.

______ _____ Mate the RTD/TEC connector using 4-40 x 3/16” screws torqued to 8 in-lbs.

______ _____ Mate the detector connector. Perform this operation on an ESD mat while wearing a grounding strap. Drain the electrical charge from the detector through the ground lug on the Positronics shorting plug. Drain the sensor base harness electrical charge through its shorting lug. Remove the positronics shorting plug from the detector flexprint and mate the connector with the sensor base harness.

______ _____ Photograph the sensor base assembly.

______ _____ Install the sensor base cover using M4x.7x14 mm screws for all but the two screws over the connector plate which should be M4x.7x10 mm screws. Torque all cover screws to 10 in-lbs.

______ _____ Measure the resistances shown in the table below:

|Pins |Nominal |Actual |

|4-5 |0 Ω | |

|6-7 |0 Ω | |

|4-6 |111 Ω | |

|5-7 |111 Ω | |

|12-13 |0 Ω | |

|14-15 |0 Ω | |

|12-15 |111 Ω | |

|13-14 |111 Ω | |

|1-9 |10.7* Ω | |

*Impedance at 1 kHz with HP Impedance Analyzer

______ _____ Install the sensor base onto the removable frame of the sensor base shipping container (CSR 29-50600). Torque M4 x 0.7 screws to 10 in-lbs.

______ _____ Wrap sensor base with NMD bagging material using ESD tape to secure the bagging to the lower surface of the removable frame. Leave the detector connector saver protruding form the bagging to allow electrical testing. Make a small removable cover for the connector saver and secure with tape.

______ _____ Install the shipping container frame into the shipping container using the supplied 10-32 screws. Torque to 30 in-lbs.

______ _____ Verify that the shock watches have not been tripped. If they have been, reset using supplied tool.

______ _____ Install shipping container cover.

______ _____ Perform a Keithley test on the detector. Record the test number below.

Keithley Test Number: ___________

______ _____ Deliver to CSR

Process Outline:

Stake wires leaving TEC

Mask TEC and add tapped holes

Measure height of TECs relative to standoff areas

cut standoffs 0.006 short

clean standoffs

Temporarily tape RTD in place

install connector plate torque to 8 in-lbs

wire TEC and RTD to connector

splice larger wire to RTD leads

measure TEC impedance and RTD resistance

Install RTD to heatsink using EA 9394 and 0.006” diameter bond wire

Tape off area so glue doesn’t splash onto surrounding area

Tape in place

Add 2 cubic inch steel dead weight

stake wire in place

measure TEC impedance and RTD resistance

install standoffs onto dummy alumina with shrink tubing on screws to center

place 0.001 thick shim on bottom of alumina where TEC will interface

solvent clean gold tric/acetone/2-proponal

acid etch with selvage brush

water break test

dry

silane coat

RT air dry 1 hour

60 deg bake 10 minutes

install alignment fixture

load alumina/standoffs onto heatsink

verify shims required to prevent tilting

mix glue

apply light layer to bottoms of standoffs

lightly install on heatsink to mark area

work adhesive into surfaces of heatsink and bottoms of standoffs

wipe off all excess adhesive

lay bead down CL of annular ring on bottom of standoff

install alumina/standoffs and deadweight

verify some squeeze out around entire perimeter

wipe off excessive glue

air cure for 18 hours

remove fixture, leave alumina on, remove 0.001” thick shim from top of TEC

oven cure at 60°C for 1 hour, slow cool

trim shims from under standoffs

remove alumina

measure heights of standoffs on leveling plate

install tape on standoffs and add vent holes

Install Detector

clean bottom side of detector where TEC will bond and top of TEC

install detector guide fixtures again

Install detector onto standoffs

verify at least 0.0005” clearance to TEC and not more than 0.002” using plastic feeler gage

mix RTV

remove detector

small dab of RTV on top of TEC

install detector with washers under screws and torque to spec

remove detector guide fixture

mount flexprint connector to connector plate

install flexprint standoffs

stake hardware

top of standoff screws

standoff to bottom of alumina substrate

Positronic to connector plate hardware

connector plate to heatsink screws

flexprint standoffs to heatsink

flexprint cross bar to standoffs

flexprint screws to flexprint

Cannon connector jackposts and nuts

Install in sensor base for shipment or testing. Torque screws to 34 in-lbs.

Mate connectors

Test TEC and RTD resistances

Measure detector location wrt to bonnet pins

Measure shield location relative to detector

Keithley measurement

Qualification testing

Measure detector position relative to bonnet pins.

Keithley test at LL

CSR tests detector performance while cold

CSR tests TEC performance (control loop stability, power consumption vs operating temp)

Keithley test at LL

Measure detector temperature achieved when the TEC gets nominal design current and sensor base is held at -40°C in a vacuum.

Thermally cycle the complete sensor base while in a vacuum bell jar and monitor TEC impedance and detector's RTD. The detector is not connected to any read-out electronics during the thermal cycling tests.

Power cycle the TEC while the sensor base is held at -70°C while in a vacuum bell jar and monitor detector's RTD. Measure TEC impedance occasionally while cold and before & after testing at RT. The detector is not connected to any read-out electronics during the power cycling tests.

Keithley testing at LL

Measure detector position relative to bonnet pins.

Shake the sensor base (random and shock, no sine as far as I know) and monitor TEC impedance during tests.

Keithley testing at LL

Measure detector position relative to bonnet pins.

Detector performance while cold at CSR

Test TEC performance (control loop stability, power consumption vs operating temp) at CSR

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