VT HOKIESAT ASSEMBLY PROCEDURE &nbs

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VT HOKIESAT ASSEMBLY PROCEDURE                                                     DATE:_____________
Part # **____________________

Safety notes, Prep work: Any safety precautions or notes should be listed here. For example, if rubber
gloves, aprons, etc should be worn, specify that here. For clean room assemblies, make a note that all
parts including fasteners should be properly cleaned before entering the clean room area.

Step-by-Step Procedure; __ steps, __ pages

List steps as numbered bullets. Be as thorough as possible.

If procedure requires several major steps/hours/days to complete, include a time log as shown in the
following section.

The last step in your procedure should be to record the new part number in the tracking log, complete
configuration log, and complete assembly log. The numbers for these logs will be assigned when they are
picked up before assembly begins.

Time Log

Date: ________ Start procedure time: _________ a.m. / p.m. Stop procedure time: _________ a.m. / p.m.

Date: ________ Start procedure time: _________ a.m. / p.m. Stop procedure time: _________ a.m. / p.m.

Date: ________ Start procedure time: _________ a.m. / p.m. Stop procedure time: _________ a.m. / p.m.

Etc…


                                           Assembly Verification Record
Assembled by: ________________________               Signature: ___________________________ Date: ________

Witnessed by: ________________________               Signature: ___________________________ Date: ________



Required Tools:

Include a list of the tools used in the procedure.



**Part numbers and document numbers are assigned after submittal.
                                                                 (Document number)**

                             Solar Array Assembly Procedure




Introduction:
This document outlines the procedure for assembling solar arrays. This procedure will be
followed by all of the universities of ION-F as they precede to assembly their solar
arrays. It outlines a process that is to be completed at the facilities of Utah State
University and the Space Dynamics Laboratory.

Pre-USU Visit:
   1. Create 1:1 Mylar plots of the solar cell layout and Kapton placement.
   2. Create the Aluminum Template/Assembly Block with the G-10 insulating layer.
   3. Create the 70% area 6-mil stencils for cell to Kapton bonding.

Soldering:
   1. Clean the template aluminum block used for the placement of the solar cells, use
      Ethyl Alcohol and Q-tips to clean the surface. Make sure to eliminate all oxide
      residues and dirt that may have collected on the block.
   2. Clean solar cells, front and back, by using Ethyl Alcohol. In each case use Q-tips
      to do all the cleaning (Skip this step for the flight cells since they are coming
      straight from the package and are cleaner than the Alcohol will get them.).
   3. Ensure that each of the connectors from the solar cells is straight and has no bends
      in it. Accomplish this by using a small set of pliers to clamp down and straighten
      the connectors.
   4. Heat soldering iron to 600-750 degrees Fahrenheit. Lay down the first solar cell
      in the block and the second cell right behind the first and so on. Make sure that
      the cells are facing down and that the silver back is facing up.
   5. Prepare the soldering surface by applying flux, (R-type), around the connectors
      and the back panel.
   6. (This is a two-person process and should be done as follows.) One person should
      apply the solder (RMA type) with the soldering iron and the other should make
      sure that the connectors are flat against the cell’s back surface by applying
      pressure on the two connectors with two small pokers. With a free finger, apply a
      small amount of pressure down on the back solar cell to ensure that the
      connection is flat. A Weller 1/16” screwdriver tip was used as the soldering tip.
   7. The person who applies the solder can form a bridge between the soldering iron,
      the connector, and the back panel. Then apply the solder, soldering the connector
      to the cell. Drag off the excess solder away from the connectors to remove all
      burrs created excess solder.
   8. Continue this process until the last two cells need to be connected. At this point
      flip the last cell so that it lays in the opposite direction of the others. Take two
      free interconnects and place them in the open slot, so that they line up with the
      interconnects from the other cells. The smaller ends should be on the last cell
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        (this will give a large enough pad off the back of the string of cells to solder the
        end termination tab onto the interconnect).
    9. Solder the smaller ends of the interconnects to the end cell. Then flip the cell
        around and place it in line with the other solar cells. Solder the connections
        together using the same techniques described previously. The string should
        almost be complete and there should now be interconnects at the top and bottom
        of the string.
    10. Finish the string by soldering on the end terminations. Line up the end
        terminations with the last two connectors at each end of the string and solder them
        together. The process is very similar to soldering the interconnects.
    11. Flip the solar cells over by placing something on the back of them, I.E. a notepad,
        and slowly turn them over. Using two vacuum pens are helpful for moving the
        cells. Check for cracks in the cells. Small cracks in the direction of current flow
        are acceptable, but cracks perpendicular to the current flow, thus cutting of
        current, are unacceptable.
Estimated Time for Work: 2-3 hours for first string 1-2 hours for each string there after.

Kapton Affixing Process (KAP):
The KAP process is to be done in at least a 100,000 clean room.
    12. Thoroughly clean the substrate with Q-tips or a lint free cloth and Ethyl Alcohol,
        clean by wiping in one direction and then in the direction perpendicular to the
        first.
    13. Use the Mylar Kapton plot to mark where the Kapton will be affixed to the
        substrate.
    14. Prime the substrate and the Kapton with (CF1-135). Apply the primer with a fine
        tipped paintbrush. The primer coat should be visibly white when dry, but should
        not be thick enough to crack. Wait at least 30 minutes, but no more than 18 hours
        for the next step.
    15. Dispense enough silicone, with the application gun, for the Kapton bonding in a
        disposable beaker. Degas this silicone by pulling a vacuum down to no less than
        28 inches Hg.
    16. Apply the silicone, (CV 2289), to the primed substrate. Place the Kapton sheet
        over the silicone and roll out the air bubbles using a rubber roller. Work time for
        CV2289 is 2 hours.
    17. This can be heat cured in 15 minutes at 65 degrees Celsius, or at room
        temperature the cure time is 24 hours.
    18. Take the substrate and Kapton through 10 thermal cycles to be certain that the
        process has worked. Use a temperature range from –45 to 85 degrees Celsius.
Estimated Work Time – Approximately 8-10 hours for five panels for two people. Not
including thermal cycles.

Solar Cell Affixing Process (SCAP):
The SCAP process is to be done in at least a 100,000 clean room.
   19. Prime the back of the solar cells and the Kapton to be bonded to, with primer
       (CF1-135). Use a priming technique similar to that of the KAP (step 14). Wait at
       least thirty minutes, but no more than eighteen hours to apply the CV 10-2568.
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    20. Use the appropriate stainless steel stencil for the silicone application.
    21. Prepare the next silicone, (CV10-2568), which is a two-part mixture. Mix equal
        masses of the two-part silicone and degas the mixture (Approximately two grams
        of each part for 8 cells). Apply the silicone to the substrate. Use a skiving tool to
        make sure that the silicone is an even, uniform height with the stencil.
    22. Remove the stencil and place the solar cells on the silicone. Make sure that
        positive end of the string is matched to the negative end of the other string. I.E.
        make sure the strings lay in opposite directions. Then place the solar panel in a
        vacuum bag and pressurize, at a pressure equivalent to 12 inches of water, to
        remove all the bubbles, for 18 hours. The CV10-2568 can be heat cured for 4
        hours at 65 degrees Celsius, or even less at higher temperatures (refer to the data
        sheet for cure times at different temperatures).
    23. The vacuum bagging procedure is as follows.
            a. Place the panel with the affixed solar cells on a larger aluminum (or some
                other stiff material) that is at least 1-2” larger in all dimensions than the
                flight panel whose cells you are bonding. This larger panel will serve as a
                back plate for the vacuum bagging.
            b. Affix to the back plate a continuous border of sealant tape around the solar
                panel. This boarder will contain four pieces to form a rectangle around the
                solar panel. The pieces of tape need to be flush to the end of the next
                piece to create an adequate seal when the vacuum will be pulled.
            c. Cut out a piece of vacuum bag large enough to cover the sealant tape
                border. Cut a small hole in the bag for the nozzle to slide through.
            d. Place the nozzle through its hole in the vacuum bag and then place the pair
                on the solar panel (or the back plate if there is room). Seal the vacuum
                bag around the solar panel using the sealant tape. The hole for the nozzle
                and the nozzle will need to be wrapped with sealant tape to prevent leaks
                in that area as well.
            e. Affix the hose from your compressor/vacuum pump to your nozzle and
                either place the vacuum bagged back plate in an oven if the silicone will
                be heat cured, or place the apparatus in an acceptable place for the
                duration of the cure time.
Estimated Time for Work – Working time 3 hours for a smaller panel – Down time 4 hours