| Matej Roguljic wrote: | 10.9.
Modules 1504,1505,1520 brought to PSI after irradiation to 1.2 MGy in Zagreb. All 3 were not working when put under test with pXar. 1504 and 1520 couldn't set Vana at all. 1505 could set Vana, but timing couldn't be found and pixels weren't responding. Inspection under the microscope showed some "white-greenish" deposits on the metal pads on the HDIs which are most likely shorting the ROC pads causing the module to be non-responsive
11.9.
Removed cap from 1504 to take a better look under the microscope and some photos. The good news is that the glue holds really well. The deposition looks like a crystal growth. It reminded Danek of the humidity issues they had at CERN in 2014. Touching it with a needle showed that it is not completely solid, like "wet-snow", however, on some pads, the deposition was more solid. There was also small transparent liquid deposits observed. Prepared 3 modules for cap gluing training; 1047, 10X1, 10X2. Only 1047 works (partially) and Reception test was performed on it. Two gluing jigs prepared in the assembly lab.
12.9.
Ran reception on 1509, it will go to ETH for irradiation (not really sure if it's ETH). Further tested modules 10X1 and 10X2. X2 should have hubID set to 17,25 after which the ROCs are programmable, however, there is no readout. X1 should have hudID 31,30; but only TBM with hubID 30 works, ROCs are programmable, but no readout as well. Glued protection cap to a module 10X1. Roughly 4 minutes after the start of mixing, the glue starts to become fairly solid which gives us a constraint on the time it takes us to apply it to a module.
13.9.
Glued caps on 1508 and 1047 using the jig further from the entrance door of the assembly lab. 1508 was glued first and had an asymmetrically placed cap (one side of the cap quite close to the wirebonds). The stage was adjusted so the cap glued to 1047 was properly placed. An unused HDI was found 8-011, it was tested and found to be working until the HV test where it started sparking at -1000V, similar to 8-010. There are burn marks visible under the microscope on the same position as the ones on 8-010.
16.9.
Investigated further the sparking issue with the HDIs. Ed Bartz took a look at the photos and identified that the damaged part of the TBM is the protection diode of pin 46.
17.9.
Equipped the coldbox with 4 DTBs which makes it possible to do qualification on 4 modules at the same time. Investigated phase2 ROC-HDI gluing jig. |
18.9.
Decided on a final HDI irradiation test. We will have an HDI without components in a bag filled with nitrogen (N2 bag), HDI with components in N2 bag, Dummy module (HDI with cap glued on it) in N2 bag, Dummy module not in an N2 bag and and an HDI with components cleaned by Silvan not in an N2 bag. The idea is to expose them to irradiation in a dry environment to check if there will be weird deposits on the metallic pads of the HDI. With the 2 samples not in an N2 bag we will see if there are some deposits again. To do so, before irradiation we will inspect them under a microscope and take photos and inspect them immediately after irradiation.
Furthermore, a possible explanation for the HDI sparking problem was devised and solutions, if necessary. It is described in more details in a separate log entry. |