Lin Ruyan always said, "The thicker the finished copper on the circuit board, the more wide the line width and the distance between the lines

Her friend Jiani said, "It must be

Xiao Qi, who secretly loves Jiani, always agrees with a smile and says, "What the beauty says is right

As for the reason, he only knows a rough idea, but he cannot provide a specific one, two, or three.

However, in reality, some things are always surprising.

Xiao Qi is in the market.

The customer said that I have a 14 story board that I worked late every day for two months, and the delivery time is very urgent. Can you help me catch up.

Xiao Qi said yes.

Just looking at the customer's partial drawings shows that the PCB is very dense, and the design is indeed not easy, which tests the factory's processing ability.

But after receiving the board, as soon as the engineer evaluated it, the problem arose.

The inner layer of the PCB requires a thickness of 2OZ copper, and the inner layer is designed with a line width of 3.5/3.5mil, which exceeds the processing capacity of the process.

Suggest the customer to modify the thickness of the inner copper layer to 1OZ. The customer said that the simulation has been done and cannot be modified, but to meet the current carrying capacity.

Communication has reached a deadlock, production cannot continue, but the delivery time is urgent.

Xiao Qi became anxious for a moment and became angry, but felt powerless.

It's already 11 o'clock at night, sitting alone in the car, feeling depressed and depressed.

Xiao Qi, who was in confusion, suddenly heard the sound of Duang Duang tapping on the car window. Looking up, she found that Jiani was holding two bottles of snowflakes in her hand, staring at a pair of watery big eyes. She smiled and said, "Brother, there's nothing wrong with a bottle of snowflakes being uneven. I want to have a drink now, come, take a walk

Xiaoqi saw the goddess she had been fond of for a long time and stayed in the car for a moment.

Jiani said, "Why are you still in a daze? Someone can accompany you to drink snowflakes, but not necessarily accompany you to explore the world. And I can do both. Brother, tell me your story, look at how worried you are. This is not the optimistic Xiaoqi in my mind." At this moment, Xiaoqi's calm heart began to surge.

There is a 3.5/3.5mi line width line spacing in some parts of the board.

Don't look at the lack of lines, but there is no space inside BGA that cannot be moved.

Customer's stacking design and copper thickness requirements:

To explain the reason for this case, we need to start with the PCB processing process. The circuit processing of circuit boards is achieved through the main processes of graphic transfer and etching.

The processing process of the inner circuit is as follows:

DES represents development; Etching; The abbreviation for the film removal process.

The following diagram shows the process of DES:

Inner layer etching principle: It is to remove unnecessary copper foil under acidic conditions. The outer layer is an alkaline etching process.

From the above figure, we can see that the inner circuit processing is to protect the required graphics with dry or wet film

Come on, etch the copper foil that doesn't need to be left behind with acidic solution.

Etching is the use of chemical methods to remove unwanted metals at a certain depth.

Etching factor:

During the etching process, the etching solution not only exerts an etching effect downwards but also on both the left and right directions. Side etching is not

Avoidable. The ratio of lateral etching width to etching depth is called the etching factor.

Lateral erosion cannot be completely eliminated, we can only minimize it.

The etching factor is an indicator used to consider the amount of side etching, as the side etching amount may vary depending on the thickness of the finished copper product

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