Flat-flex "dendrites" - Page 1
Forum section: electronics / repair

author: I_Code_4_Hugs
author_rank: Newbie
timestamp: July 04, 2018, 07:16:31 pm
content: My Samsung Blu-ray player had been acting up by randomly switching off. Upon disassembly, finding nothing loose, I put the cable under the microscope and found "dendrites" shown in the attached image.Disconnecting the flat-flex solved the problem. Simple fix, but interesting failure mode.Has anyone else seen something similar?

author: joeqsmith
author_rank: Super Contributor
timestamp: July 04, 2018, 07:40:44 pm
content: Yes, on a hard drive ribbon cable that went to the head.

author: kony
author_rank: Regular Contributor
timestamp: July 04, 2018, 07:41:32 pm
content: What voltage is present across those two tracks? Looks like electromigration of the printed thick film paste metal to me.

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: July 04, 2018, 08:29:31 pm
content: Looks like CAF.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: July 05, 2018, 03:29:47 am
content: Quote from: kony on July 04, 2018, 07:41:32 pmI would agree there must be a DC voltage present, one side is clearly an anode the other cathode. As I understand tin pest is different, it generates from the surface energy of the plated tin all by itself. With even no DC present, you would expect whiskers coming in randomly from all directions.

author: helius
author_rank: Super Contributor
timestamp: July 05, 2018, 04:23:49 am
content: Quote from: In Vacuo Veritas on July 04, 2018, 08:29:31 pmFor those playing along at home, CAF areconductive anodic filaments.This failure mode can be very hard to detect when it migrates on interior layers.

author: mzacharias
author_rank: Frequent Contributor
timestamp: July 06, 2018, 05:31:43 pm
content: SATA connector, never used, went up in flames inside my desktop computer. Apparently they can grow these internal shorts.

author: Ranayna
author_rank: Super Contributor
timestamp: July 06, 2018, 07:42:14 pm
content: Those Molex to SATA adapters with the molded SATA power connector are infamous in IT.They spawned the expressen "Molex to SATA - lose all your data"...There are a lot of pictures of various SATA devices going up in flames, and in almost all cases, one of those stupid things was used.

author: envisionelec
author_rank: Frequent Contributor
timestamp: July 06, 2018, 09:20:53 pm
content: Yes, on a Maytag dishwasher control panel. $150 for a new one...You might be able to blow the dendrites away with a carefully controlled burst of energy between the two conductors.

author: exit_failure
author_rank: Regular Contributor
timestamp: July 06, 2018, 09:57:11 pm
content: Has there been any real explanation for the countless instances of melted or even burning SATA to Molex adaptors? Thin wires? Bad mechanical construction? Divine retribution?

author: german77
author_rank: Regular Contributor
timestamp: July 07, 2018, 01:25:27 am
content: Quote from: exit_failure on July 06, 2018, 09:57:11 pmYes basically they are made as cheap and fast as possible. The cables inside are basically not in the correct position and some build failures like the flat-flex until they arc.This video has a nice examples of the bad manufacturing

author: oventech
author_rank: Contributor
timestamp: July 13, 2018, 03:17:48 am
content: Are they made with a mechanical connection? Reminded me of tin whiskers due to ROHS.