RD53a quad modules consist of four front end chips and gaps between them. We must keep glue clear of the gap. 

Model is the RD53a Quad .step model in EDMS (here: https://edms.cern.ch/document/2363540/1). Scott extracted a sketch illustrating some dimensions in that model. 

Cut glass to quad module size for glass-glass glue tests 

Matt has cut glass to the size of quad modules for us to make mounting tooling tests. At Scott's request, Matt measured 10 samples: 

40.91 x 42.49
40.92 x 42.32
40.99 x 42.34
40.84 x 42.50
40.99 x 42.42
40.92 x 42.54
40.93 x 42.57
40.96 x 42.42
40.99 x 42.50

Quad mechanical module properties 

Scott & Charlie used the CMM on 23 February 2021 to measure the mechanical quad's thickness. Katy and Neha explored the flatness of the vacuum pads on the quad module bridge pick up tool in response (see February 23, 2021: Height measurements for the quad bridge)

Hi Caterina and all,

Measurements attached from measuring the mechanical Quad yesterday with Charlie – graph and illustration of which points were where. Measurements were done using a touch probe. The mechanical Quad was placed onto the granite table surface a few points were measured in each clear area where the vacuum tool will pick up, and a few additional points on the granite table surface as a reference. It looks like there is variation of ~20 microns within one vacuum area (depending on if the probe touches onto a wire trace or not), and additionally variation of ~50 microns between two areas. The measurements of the granite table surface at 4 points were identical height.

It might be worthwhile to repeat this measurement with the other 2 Quad modules we have, to better understand what variation we should expect.

If it really is ~50 microns variation within a Quad, then we may need to think about how to accommodate that to maintain a consistent glue layer thickness and not over/underfill. From discussion with Matt, one approach would be to modify the loading bridge to adjust the height of the vacuum pads when the module is on the pickup table (held flat by the vacuum to the bottom of the cutout), so that the different heights of the loading bridge would keep the front surface of the FE chips closer to flat/coplanar during gluing.

Cheers,

Scott

mechanical quad thickness measurement 22Feb2021.pdf