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Thermomechanical modules (TM)

The wirebonding and testing of TM modules is described here and the shipping to Brookhaven is described here.

Important rule for this entire process: Most of the pieces are marked with a 'T', this is for alignment. Always place the equipment so that 'T' is over 'T'.

Mixing the glue

There are two kinds of glue used. Silver epoxy (Loctite Ablestik 2902) is for gluing the chips to the hybrid, regular epoxy glues the hybrid to the base plate. The silver epoxy is in a box in the freezer in the clean room, the regular epoxy (Epolite 5313A) is in the strips cabinet.

The epoxy is two liquids, mix the well inside the plastic container then pour out the mixture onto a piece of plastic in the epoxy mixing station. Take the glue spreader and replace the tape on the end. Use this to spread the glue.

The epoxy solidifies over time after it is mixed. Use it within ~15 minutes of mixing it, however allow it ~24 hours to dry. Important note: it will start to solidify once mixed, whether or not it is exposed to air, meaning if it is mixed but still in the plastic tube it came in it will still solidify.

Gluing the hybrid

The Hybrids come on a hybrid panel, for the TM modules there are version 1.1 and 1.2 hybrids (1.2 are wider where the HCC is).

Note: Most pictures are from the first electrical module as this was when I was actually taking pictures. In principle the assembly is the same.

IMG_20170405_163228140_HDR.jpg

This panel is screwed onto a base plate. Clean the hybrid you plan to glue with ethanol and a Q-tip, and connect the vacuum to the hybrid you plan to glue.

The chips (for TM modules they are glass) are placed one at a time using the vacuum pen in the positioning base plate. The unpatterned chips are much smaller than the patterned chips and the real chips, and need to be aligned carefully in the base plate.

Chip_Placement.jpg

Once these are placed check their alignment under a microscope. Now use the vacuum jig to pick up all of the chips at once. Important note: there are three vacuum jigs but only one works for a given task. Part A of the jigs is missing the metal support so it is not usable. Part A fits on the positioning base plate so it should be used for chips to hybrid. Part B works for the module base plate (not yet mentioned), so it should be used for the hybrid to module step.

Connect the appropriate vacuum jig to the vacuum but do not turn on the vacuum yet. Place the vacuum jig on the positioning base plate with the rotating legs down so that it stands above the chips. Carefully check the alignment and slowly lower the vacuum jig so that it comes down parallel to the plate. Lower until it is all the way down, the four bumps on the jig should be touching the base plate. Turn on the vacuum.

Slowly lift up the vacuum jig and check the alignment of the chips. Lower the glue plate on the jig (the plate with 5 holes for each chip) slowly and evenly.

IMG_20161220_145548216.jpg

Now get the silver epoxy and the glue spreader. Get a dab of epoxy on the tip of the spreader and spread it on the glue plate. Do not press down very hard or else it will spread out on the chips to much.

Glued_Chips.jpg

Now slowly lower the jig on the hybrid panel (again lining up 'T' over 'T'). Lower it evenly and once it is all the way down place the weight on top of the jig and let it solidify for 24 hours.

IMAG0315.jpg

Gluing the Module

Take the base plate for the sensor plate and place the sensor on it (on top of the piece of paper to spread the suction). The strips should be running parallel to the metal supports along the sides. Line the sensor up so the it is touching both of the metal pins, then turn on the vacuum.

IMG_20170504_072735019_HDR.jpg

Check that the jig can be lowered down all the way on this base plate (again line up 'T' over 'T'). Now with the vacuum to the hybrid panel turned on cut the connectors from the hybrid to the panel.

hybrid_Connectors.png

Lower the jig on the hybrid panel, turn off the vacuum to the hybrid and turn on the vacuum to the jig. Now slowly lift up the hybrid and lower the hybrid glue plate onto the jig.

IMG_20161220_145628528.jpg

Spread the regular epoxy on this glue plate, again do not push too hard or else it will seep out along the edges. Now with the epoxy on the hybrid slowly lower it down onto the sensor plate and place the weight on top of the jig. Again wait 24 hours for the glue to harden.

IMG_20170504_074128970.jpg

Powerboard Placement

The powerboard is placed between the hybrids. There are multiple different methods used. I will briefly go over them. In short the glue is spread on the sensor, spacers are put between the board and the sensor, the board is placed on the glue, then weighed down over night.

powerboards.jpg

Glue Spreading:

The glue is spread by hand by the technician, we used the epolite epoxy with a cure time of 24 hours. There are multple concerns with the glue. There needs to be enough that the bond pads are stable and do not bounce, and there needs to be enough under the coil that it makes good thermal contact with the sensor. There should not be so much that it leaks over and glue seeps onto the top of the hybrids or the bond pads.

Glue_Trial.jpg

Spacers:

There are 2 methods that we used for spacers:

1. As Brookhaven suggested we placed kapton tape on the bottom of the powerboards. One piece on each and and one in the middle. This was not trivial to do as we needed to cut and handle small pieces of kapton and place them without damaging the board much. This was done for 9 of the powerboards.

2. As Santa Cruz suggested we used fishing line. We cut short pieces and placed in the glue. This seemed to set the height as well and was very easy to do. There is some uncertainty on the thickness of the fishing line.

Glue.jpg

Board Placement:

The board was placed by hand on the sensor. The bond pads for power need to line up between the powerboard and the hybrids, and the power pads at the end of the board need to be close enought that they can be bonded to the test frame.

It is important to note that the guard ring on the sensor is sensitive and should not get glue on it. This will effect the electrical characteristics of the sensor and should be avoided. As such some of the TM modules had the powerboard shifter further back to avoid touching the guard ring at all.

Weighing down:

The tooling produced at BNL applies pressure to the chips in the center of the PB. The powerboard arcs up so pushing in the middle will flatten it out. The individual legs can be adjusted to change the height of this tooling.

We also produced a small piece of tooling that pushes in the center and presses the powerboards to the sensor. This allowed multple gluings to happen at once.

PB_Tooling_Top.jpg PB_Tooling_Side.jpg PB_Tooling_Support.jpg

-- Tom-Erik Haugen - 2016-11-29

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JPEGjpg Chip_Placement.jpg r1 manage 3979.4 K 2017-04-10 - 16:11 TomErikHaugen  
JPEGjpg Chips_on_Jig.jpg r1 manage 2920.2 K 2017-04-10 - 16:11 TomErikHaugen  
JPEGjpg Glue.jpg r1 manage 4564.1 K 2017-07-21 - 17:02 TomErikHaugen  
JPEGjpg Glue_Trial.jpg r1 manage 4648.9 K 2017-07-21 - 17:02 TomErikHaugen  
JPEGjpg Glued_Chips.jpg r1 manage 2861.1 K 2017-04-10 - 16:11 TomErikHaugen  
JPEGjpg IMAG0315.jpg r1 manage 3287.5 K 2017-07-21 - 06:14 TomErikHaugen  
JPEGjpg IMG_20161220_145548216.jpg r1 manage 3782.4 K 2017-07-21 - 06:12 TomErikHaugen  
JPEGjpg IMG_20161220_145628528.jpg r1 manage 3787.3 K 2017-07-21 - 06:24 TomErikHaugen  
JPEGjpg IMG_20170405_163228140_HDR.jpg r1 manage 2939.2 K 2017-07-21 - 06:07 TomErikHaugen  
JPEGjpg IMG_20170504_072735019_HDR.jpg r1 manage 5891.2 K 2017-07-21 - 06:15 TomErikHaugen  
JPEGjpg IMG_20170504_074128970.jpg r1 manage 4773.2 K 2017-07-21 - 06:16 TomErikHaugen  
JPEGjpg PB_Tooling_Side.jpg r1 manage 4038.7 K 2017-07-21 - 17:02 TomErikHaugen  
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JPEGjpg PB_Tooling_Top.jpg r1 manage 6163.3 K 2017-07-21 - 17:02 TomErikHaugen  
PNGpng hybrid_Connectors.png r1 manage 4414.5 K 2017-07-21 - 06:19 TomErikHaugen  
JPEGjpg powerboards.jpg r1 manage 4772.2 K 2017-07-21 - 17:02 TomErikHaugen  
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