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2016/03/31 (Thursday)

0900	More on the attempt to fix G114 DIB1 pin1.
	Tried cleaning off the wirebond stubs from the pad on the detector, by gently scraping first with sharpened end of wooden swab, then (very gently) with hypodermic needle, using wirebonder microscope. Both about equally effective, some debris removed but lots remaining. Cleaned off debris by dabbing with bit of wipe dampened with isopropanol.
	Scraped newly made DIB bond pad with scalpel to get shiny surface
	Successfully formed two bonds from DIB to detector pad using slight variation on settings from yesterday: bond1/bond2 set to powers 480/475, bond times 40/30, loop height 50 mils, drop before clamp 20 mils
	Pin1-Pin2 (DIB1pA) no longer open, but rather high - about 1500 Ohm after first bond, about 1400 Ohm after second.

Pad on detector, after attempted cleaning	Newly made DIB pad, before scraping

Finished wire bonds

1115	Take repaired G114 into clean room for electrical check.

+lead	- lead	signal	typical	measured
Detector	G114	DIB	1
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	810Ω (or 1.51 kΩ measured 2→1)
3	4	QET B	100 to 200 Ω	170.8 Ω
5	6	QET C	100 to 200 Ω	131.3 Ω
7	8	QET D	100 to 200 Ω	72.0 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	open
9	chassis	LED1 Vforward	1.0 to 1.1 V	open
chassis	9	LED1 Rreverse	<1 nS	<1 nS
10	chassis	LED2 Rforward	8 to 9 MΩ	735kΩ
10	chassis	LED2 Vforward	1.0 to 1.1 V	1.041V
chassis	10	LED2 Rreverse	<1 nS	<0.2nS
11	12	Qo-Qi		90.4Ω
12	11	Qi-Qo		85.3Ω

NOTE	When measuring other channels besides DIB1 pA in reverse (i.e. pins 4→3 instead of 3→4), we measured similar readings as the forward resistances. Only with DIB1 pA was the reverse value drastically different.

+lead	- lead	signal	typical	measured
Detector	G114	DIB	2
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	159.7 Ω
3	4	QET B	100 to 200 Ω	35.4 Ω
5	6	QET C	100 to 200 Ω	open (<0.2nS)
7	8	QET D	100 to 200 Ω	35.2 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	733kΩ
9	chassis	LED1 Vforward	1.0 to 1.1 V	1.040V
chassis	9	LED1 Rreverse	<1 nS	<0.5nS
10	chassis	LED2 Rforward	8 to 9 MΩ	735 kΩ
10	chassis	LED2 Vforward	1.0 to 1.1 V	1.042V
chassis	10	LED2 Rreverse	<1 nS	<0.5nS
11	12	Qo-Qi		396kΩ
12	11	Qi-Qo		1.2 ± 0.2MΩ

NOTE	Pin 5 is connected to all other phonon channels, whereas Pin 6 is open to all other phonon channels. Pin 6 is the pin that's disconnected now.

+lead	- lead	signal	typical	measured
Detector	G114	DIB	3
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	open
3	4	QET B	100 to 200 Ω	84.7 Ω
5	6	QET C	100 to 200 Ω	30.7 Ω
7	8	QET D	100 to 200 Ω	83.3 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	open
9	chassis	LED1 Vforward	1.0 to 1.1 V
chassis	9	LED1 Rreverse	<1 nS
10	chassis	LED2 Rforward	8 to 9 MΩ	open
10	chassis	LED2 Vforward	1.0 to 1.1 V
chassis	10	LED2 Rreverse	<1 nS
11	12	Qo-Qi		open
12	11	Qi-Qo		open

NOTE	Neither pins 1 or 2 showed connections to any of the other phonon channels, suggesting that both pins 1 & 2 are disconnected now.

1200	After examining the wirebonds visually, we saw several “hanging” wirebonds on DIB3 (i.e. only attached on the DIB pads). It appeared that all four wirebonds that connect DIB3 pins 1&2 were affected. DIB2 pin6 was less visually affected, but it's most likely a similar diagnosis.
	Reattach cover of G114 and replace in anteroom for more wirebonding.
1205	Remove tower from purge cabinet and remove copper plate from bottom of Side 6 to examine missing socket. It appears that the sockets are simply soldered to a pad at the bottom of the tower. The fear is that the pad may have come off completely.
1235	The pad has come off, though there's a small dot where the wire from the tower face comes through the PCB and connects to where the pad/socket should be.

Tower face with plate removed. There's a wire running through each channel.	Missing socket	Missing socket

Screws removed from the connector board of one of the “bad” faces. The board hinges out somewhat under the tension of the wires.	Screws removed from the connector board on the face with the missing socket.

There's no clear way to fix this.

Unsorted tower pictures

1235	Perhaps some of the other “bad” tower faces are more easily fixable. Test through-connections of each Tower Face.

Tower Face	Good Trace Resistances	Open Traces	Shorted To Ground	Shorts from One Pin to Another
Face 4	~27Ω	none	none	none?!?!
Face 5	~27Ω	none

1500	Repaired DIB-to-detector connections for DIB2 pin6 and DIB3 pins 1&2 with the wirebonder. Scraped DIB pads gently with scalpel or hypodermic needle in direction along the trough.

1550	Back in the clean room after a long afternoon of run-diary investigations to determine what had caused the labelling of “Bad” for Tower Faces 1,3,4. In the run diary all that is said is that after using Tower Face 4 in Run 4, the tower level electrical check for Run 5 said:

One connector found to have a damaged pin.
One connector gave strange results when an electrical check was performed.
Both sides have been labelled so as not to be used again.

	No other information is given in any of the surrounding daily run-diary pages. The official electrical checkout for Run 5 only lists Tower Face 5, which was finally used after the two anonymous faces were deemed bad (we suspect Tower Faces 3&4. According to an eLog entry Tower Face 1 was already bad when it was sent to us.

	In the clean room begin examining face 3 because if that's actually good, we could run using Faces 2,3,5.

Tower Face	Good Trace Resistances	Open Traces	Shorted To Ground	Shorts from One Pin to Another
Face 3	~28Ω	none	Loose Socket 15, which could short to ground or other pins. Socket 1 shorts to the 4K stage, but not 600mK ears.	Potentially Socket 15
Face 1	~29Ω	Socket 5,6,7,8,9,10	Did Not Bother	Did Not Bother

1620	Repaired G114 is back in clean room. Perform detector level electrical checkout:

+lead	- lead	signal	typical	measured
Detector	G114	DIB	1
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	809Ω (or 1.6 kΩ measured 2→1)
3	4	QET B	100 to 200 Ω	171.0 Ω
5	6	QET C	100 to 200 Ω	131.3 Ω
7	8	QET D	100 to 200 Ω	72.0 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	open
9	chassis	LED1 Vforward	1.0 to 1.1 V	open
chassis	9	LED1 Rreverse	<1 nS	<1 nS
10	chassis	LED2 Rforward	8 to 9 MΩ	742kΩ
10	chassis	LED2 Vforward	1.0 to 1.1 V	1.042V
chassis	10	LED2 Rreverse	<1 nS	<0.2nS
11	12	Qo-Qi		90.7Ω
12	11	Qi-Qo		85.8Ω

+lead	- lead	signal	typical	measured
Detector	G114	DIB	2
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	158.0 Ω
3	4	QET B	100 to 200 Ω	35.4 Ω
5	6	QET C	100 to 200 Ω	108.7 Ω (backwards reading 6→5 read similar value)
7	8	QET D	100 to 200 Ω	35.3 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	740kΩ
9	chassis	LED1 Vforward	1.0 to 1.1 V	1.042V
chassis	9	LED1 Rreverse	<1 nS	<0.3nS
10	chassis	LED2 Rforward	8 to 9 MΩ	742 kΩ
10	chassis	LED2 Vforward	1.0 to 1.1 V	1.043V
chassis	10	LED2 Rreverse	<1 nS	<0.3nS
11	12	Qo-Qi		484kΩ
12	11	Qi-Qo		1.15 ± 0.1MΩ

+lead	- lead	signal	typical	measured
Detector	G114	DIB	3
		date/who:	2016-03-31	DS & AK
1	2	QET A	100 to 200 Ω	31.2 Ω (reverse reading 2→1 gives similar result)
3	4	QET B	100 to 200 Ω	84.6 Ω
5	6	QET C	100 to 200 Ω	30.9 Ω
7	8	QET D	100 to 200 Ω	83.5 Ω
9	chassis	LED1 Rforward	8 to 9 MΩ	open
9	chassis	LED1 Vforward	1.0 to 1.1 V
chassis	9	LED1 Rreverse	<1 nS
10	chassis	LED2 Rforward	8 to 9 MΩ	open
10	chassis	LED2 Vforward	1.0 to 1.1 V
chassis	10	LED2 Rreverse	<1 nS
11	12	Qo-Qi		open
12	11	Qi-Qo		open

1625	All the broken channels are fixed. DIB1 pA is still showing high resistance, but most likely within runnable range.
1630	Back to Tower Face 3, take off the lowest copper plate and investigate to see why Socket 1 is shorted to the 4K Stage ground. It looks like the wire –unlike its brethren – is slanted in its vacuum channel and contacts the copper sidewall (see below). This is most likely the culprit of the short to ground.

Tower Face 3 Vacuum Channel Wires with 4K Stage Face-Plate Removed
Channel 1 is on the right	Brightened/Increased Contrast Image


Original: Notice How Channel 1's Wire Disappears To The Left As It Descends	Brightened/Increased Contrast Image