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I did disassemble my LG screen and fount on t-con pcb this. Why enginer cut this island on the pcb?

t-con pcb with strange island

UPDATE: I did add other side and general view. T-com it is a timing controller in lcd display. It is a pcb between main pcb and lcd panel. I see such solution first time in my life and I'm intersting is there any notes about it in literature?

Also, seems the wire on entering and exiting the island is the same.

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    \$\begingroup\$ Many reasons for a cutout like this but I don't understand why you'd do it in this type of product and with those components. Weird. What's on the other side? \$\endgroup\$ Commented 17 hours ago
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    \$\begingroup\$ Such islands are often used in high-end equipment to provide thermal and electrical isolation for a precision voltage reference or oscillator. But there's no other evidence for something like that here. \$\endgroup\$ Commented 16 hours ago
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    \$\begingroup\$ You might figure it out if you find a datasheet for the RT6811GQV but I don't think it will be found. What is a "t-con" PCB? Also does a single trace loop the island or is there two copper traces? Photo is too poor to see. \$\endgroup\$ Commented 15 hours ago
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    \$\begingroup\$ what's on the other side? \$\endgroup\$ Commented 14 hours ago
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    \$\begingroup\$ I add the other side of the pcb \$\endgroup\$ Commented 11 hours ago

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Given that the PCB traces continue outside the island, the cutout can’t be for voltage isolation. While it could be a snap-off there’s no indication of a point where that would happen, so microphonic isolation would seem to be the most likely reason. That said, it would be impossible to know with certainty without a statement from the designer(s) of the board.

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There could be multiple reasons, but it would be way more clear if you showed us the backside of the PCB, too.

Here are my two top-of-my-mind guesses:

1) Additional Trace Inductance

The designer wanted to increase the inductance between two different parts of the circuit. By cutting these slots in the PCB, the currents have to go a longer way which means increased inductance.

2) Strain Relief

Because multiplayer capacitors are very sensitive to bending the PCB, the desiger wanted to relief the strain from these capacitors.

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    \$\begingroup\$ Strain relief was my first thought but the board is littered with identical capacitors so I doubt that. \$\endgroup\$ Commented 17 hours ago
  • \$\begingroup\$ even inductance - surely it's cheaper to add a small smd inductor than having that additional cutout done on the PCB, isn't it? \$\endgroup\$ Commented 16 hours ago
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    \$\begingroup\$ How does adding the cutout increase inductance? Why not just shape the copper accordingly and leave the PCB material there? \$\endgroup\$ Commented 14 hours ago
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    \$\begingroup\$ Perhaps to reduce sound from the capacitors if they are Class II or III parts. Class II & III capacitors are piezoelectric. \$\endgroup\$ Commented 11 hours ago
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    \$\begingroup\$ On another LG TCON board that had a different Richtek chip, they used identical cutout island for two ceramic bypass caps. The other build-time option seemed to be a larger SMD component designated TC1, which I could assume stands for Tantalum Capacitor, but also the PCB traces were longer to reach that cap. So, in light of this, the Richtek chip may need very specific input/output impedance for stability, and indeed sometimes you put ceramic caps behind few centimeters of PCB trace if a regulator cannot handle low ESR of ceramic caps. \$\endgroup\$ Commented 11 hours ago
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I will go out on a limb here and say that it is designed like that so that the entire peninsula and its associated components can be snapped off and removed from the circuit without tools.

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  • \$\begingroup\$ To what end? All we can see on this side of the board is that all five components are connected between two nets, one that has a test point labeled "VDD" and another that's most probably ground. Despite the fact that there are no visible vias, there must be something mounted on the other side. \$\endgroup\$ Commented 12 hours ago
  • \$\begingroup\$ i.sstatic.net/nux3JDaP.jpg \$\endgroup\$ Commented 12 hours ago

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