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Difference between good and bad bottom of iPhone motherboard

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In this video, we mainly explain the function of the bottom of the board and the structure of the bottom of the board.

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The bottom of the board is also called the bottom of the PCB in actual maintenance.

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Its main function is to support electronic components

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To put it simply,

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Electronic components are soldered to the bottom of the PCB

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The lines will be connected by board layer traces

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Here is a picture of the bottom of the PCB board

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We can see that

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There are many thin lines on the bottom of the board

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When we solder the components to it

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The signals will be connected through these traces on the bottom of the board.

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PCB bottom structure

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From the earliest single-layer wiring to double-layer wiring on the bottom of the board

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Single-layer wiring means that only one layer of wiring is printed on the surface of the PCB.

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Double-sided means that the circuit is also printed on the reverse side of the PCB

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With the advancement of technology, the two-layer wiring can no longer meet the demand

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So now it has developed to multi-layer routing

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Multi-layer wiring refers to the fact that many layers of lines are routed inside the PCB board layer.

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The number of lines inside the PCB board layer is determined according to the design of the electronic product

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For example, the current notebook motherboards and mobile phone motherboards generally have 8-12 layers of internal circuits.

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The number of layers of lines used by different models is also different

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Next, let's take a look at what the actual board layer looks like.

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The ply is actually very thin

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After zooming in we can see

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This ply is very thin

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But inside such a thin board, it can run 8-12 layers of lines

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We can see when we scrape the side of the ply

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There will be a lot of copper wires on the side of the board

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These copper wires refer to the board layer traces

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This is the layer routing of the Apple mobile phone motherboard

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Let's take the iPhone 11 as an example to check its layer routing

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Open the board layer wiring diagram, we can see the number of different layers

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Each layer is marked with a different color

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The lines on these layers connect the electronic components

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These lines belong to the PCB board and are called internal wiring.

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This lesson we learn here