Anyone know what this is ? - Page 1
Forum section: electronics / repair

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 12:23:58 am
content: I have a small circuit that has a device I have not encountered before and I believe it is simply a grounding block, but an odd way to do it?

author: helius
author_rank: Super Contributor
timestamp: July 21, 2023, 01:06:59 am
content: The solder-covered square component looks like it may be a polyfuse.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 21, 2023, 02:26:17 am
content: would be nice to know the big part first .... have you unsealed it ?

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 02:38:42 am
content: Quote from: coromonadalix on July 21, 2023, 02:26:17 amThe large IC is a S50055C PWM ControllerIt's a Fan Control Relay for a car.

author: fzabkar
author_rank: Super Contributor
timestamp: July 21, 2023, 03:59:57 am
content: Datasheet:https://www.infineon.com/dgdl/Infineon-BTS50055-1TMA-DS-v01_00-EN.pdf?fileId=5546d4625a888733015aa9b00de935ed

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 02:43:49 pm
content: Quote from: fzabkar on July 21, 2023, 03:59:57 amI know what that IC is.The item I am unsure of is indicated by the red arrow in the photo above.Thanks

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 04:37:22 pm
content: Something else strange with this small PCB is these small black painted areas that appear to be some kind of track that was painted on but they have no apparent conductivity.I have numbered then in Red 1 - 5You can see some regular copper PCB tracks come near each other then just end, but are "joined" by this black paint or whatever it is.I have never seen this? Anyone?Thanks

author: floobydust
author_rank: Super Contributor
timestamp: July 21, 2023, 04:44:26 pm
content: Those are printed and trimmed resistors.What are the three bonding wires connecting to on the heatsink? It is the aluminum?It doesn't make any sense to me- the high current ground is at the fan, no need for it on this board. Also the mystery pad/part ends up connected to the printed resistor under "3807", thin traces so it's not high current.I thought a thermistor but don't know where the temp sensor is for this module.Is it PWM or just on/off control? I would say the Profet is driven by the SOT23-5 IC U2 possibly a comparator or op-amp.

author: luudee
author_rank: Frequent Contributor
timestamp: July 21, 2023, 04:45:51 pm
content: Quote from: ThermallyFrigid on July 21, 2023, 04:37:22 pmThose are resistors, directly printed on the PCB, and it looks like they were adjusted with a laser (small cuts).Cheers,luudee

author: tszaboo
author_rank: Super Contributor
timestamp: July 21, 2023, 04:48:00 pm
content: Looks like they bonded that pad to the housing. If I have to guess, it might be a vertical PTC fuse. But looking at this board, they are really really going for the bottom shelf electronics, cause the 0.01 cent resistor is too expensive for them.

author: boB
author_rank: Frequent Contributor
timestamp: July 21, 2023, 05:22:04 pm
content: Quote from: ThermallyFrigid on July 21, 2023, 04:37:22 pmI would have thought those black painted areas are resistors. They may still be that but covered in a conformal coating ?Maybe you just have to poke through some of that to measure any conductivity ?

author: fzabkar
author_rank: Super Contributor
timestamp: July 21, 2023, 06:14:45 pm
content: Quote from: ThermallyFrigid on July 21, 2023, 02:43:49 pmI know that you know. I just posted a URL so that everyone else who reads your thread doesn't need to search for it.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 06:20:56 pm
content: Quote from: fzabkar on July 21, 2023, 06:14:45 pmoh. my bad. thx

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 06:22:50 pm
content: Some more photos of the small aluminum block from different anglesTo me it just looks like a solid aluminum block

author: bdunham7
author_rank: Super Contributor
timestamp: July 21, 2023, 06:23:12 pm
content: Can you peel off the metal part and see what is underneath?

author: Gyro
author_rank: Super Contributor
timestamp: July 21, 2023, 06:24:12 pm
content: Quote from: tszaboo on July 21, 2023, 04:48:00 pmI wouldn't say that. If you look again, thereisa 0.01 cent resistor mounted on it. They used a ceramic substrate specifically so that they could include laser fine trimming on those resistors. That and thermal conductivity.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 21, 2023, 06:26:10 pm
content: Quote from: bdunham7 on July 21, 2023, 06:23:12 pmI will try and if successful will post a photothanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 21, 2023, 06:32:20 pm
content: Yes, for wire bonding it would seem.I'm surprised they can't do it directly to the substrate, but oh well I guess.This is known as a hybrid module. Ceramic substrate, metal enamel traces, resistive ink + laser trim resistors. Most normal SMT components can be used (reflow soldered or conductive silver epoxy), or semiconductors can be wire-bonded directly (or, can be given the right process, which the bonding block seems to call into question here).Presumably, vias could've been used instead, but probably opted against due to cost (they have to be pulse laser drilled in ceramic, or something like that; and then backside metal is required, too).Tim

author: floobydust
author_rank: Super Contributor
timestamp: July 21, 2023, 06:37:19 pm
content: It looks like a basic ground to the heatsink just for the nearby resistor.It depends on where the module is mounted, as the temp sensing thermistors old school is one-wire and grounded to the block, new school is two-wire.

author: Gyro
author_rank: Super Contributor
timestamp: July 21, 2023, 07:53:28 pm
content: Yes, my bet would be a fast responding temperature sensing thermistor. There's no way the current through that laser trimmed resistor would require three reasonably heavy bonding wires.

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 21, 2023, 09:54:44 pm
content: Considering that it's directly mounted on a substrate with lowish thermal resistance and that neither the series resistor nor track look suited for high current, my bets would be simple grounding block rather than temperature sensitive device, the 3 bonding wires would be for mechanical redundancy against vibration and/or thermal cycles.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 22, 2023, 12:44:09 pm
content: Regarding the printed resistors......I attempted to measure the resistance of the largest one but was not successful.Would I expect very low or high resistance? Would I need more than your average VOM?If that is the case, let's say you were trying to make a replacement for this.What if any procedure could be used to determine the resistance (obviously it is critical since they used a laser to fine tune it) and then use SMD resistors in place of the printed resistors?The ceramic substrate (I think) is for heat transfer purposes. A normal PCB would not be able to do this. The IC would have to be heavily heat sinked?Is that something beyond hobbyists capabilities? Requires expensive machinery?T3sl4co1l touched on it above. Any other thoughts?Quote from: T3sl4co1l on July 21, 2023, 06:32:20 pm

author: Stray Electron
author_rank: Super Contributor
timestamp: July 22, 2023, 12:54:45 pm
content: Quote from: ThermallyFrigid on July 21, 2023, 02:38:42 amWhat kind of car? That's much cruder workmanship on both the electronics board and on the metal chassis than anything that I have encountered on any of the cars that I've owned and worked on. (BMW, Ford, Nissan, Mitsubishi, Subaru, Hyundai). The workmanship on your module looks like the stuff that I see in Chinese made products. Has this module been replaced already or did it come with the car?

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: July 22, 2023, 01:01:35 pm
content: Quote from: Stray Electron on July 22, 2023, 12:54:45 pmThe module itself is a new Chinese replacement for an older Chrysler part circa 2000.The unit works by receiving a pulsed PWM ground from the PCM.In theory, The Voltage to the Radiator fans increases in proportion to the pulsewidth signal from the PCM (I think).In practice however, I find that the fans only come on LOW SPEED at 224F and turn off at 214F. At 230F they are at HIGH SPEED. I see no in between speeds so not sure why it is PWM in the first place?I do wish I had the original to see how it was made inside.Here is the schematic for the Relay circuit

author: R-1125F
author_rank: Regular Contributor
timestamp: July 29, 2023, 02:35:41 am
content: I am guessing it is a temperature sensor. Something like this:https://www.vishay.com/docs/29153/ntccx00e4.pdf