Author: Wang Huidong, a member of Yibo Technology Expressway Media
Preface
Do you know what the lead of the gold finger is?
What is its function on the PCB?
Can the short finger on the long and short gold finger have a lead?
The customer did not understand, and the factory understood, but did not clean the lead. What consequences will this bring? Please listen to my story.
Text:
Night, midnight.
A few floating clouds cannot cover the charm of the night.
A half-moon casts a chill.
It's time for the factory's late shift snack again, and the workers have gone to replenish their energy.
The lights in the workshop were basically off, and suddenly a figure floated in from outside like a ghost.
After a while, the light in front of an operating table lit up, which was the only light source in the workshop at present.
There was a vague dividing line between the surrounding darkness and the light, and the night seemed even more eerie.
Under the pale light, she picked up a cold and sharp knife, which reflected a cold and dazzling light under the light.
She lowered her head, her eyebrows slightly raised, her mouth tightly pursed, and her eyes widened, staring at the things below. Because the muscles on her face were too tight, some of the powder of the cosmetics fell off her small face and floated around the light.
The air seemed to solidify at this moment, and she just stared at the things under the light, motionless.
It felt like a century.
Suddenly she moved, and her hand was slightly raised, a cold light flashed, and with a swish, the knife fell, and a golden light flashed.
All the lights in the workshop lit up in an instant.
She slowly turned her head, stared at the workers who came in, and said, "I succeeded."
"Really?" Everyone gathered around in surprise.
"How did you do it?" Everyone asked curiously.
"I swept a large area with a stick and picked a line with a knife."
"High, really high, haha..."
Leaves fell outside, and the stars were sparse and the moon was bright.
There were laughter and joy in the room.
Customer Zhang Gong slept very uneasy that night. It stands to reason that the board will be delivered tomorrow. After so many days of busy work, he should be excited, but he always feels inexplicably irritable. Especially at night, he always has some strange dreams, such as Shaolin, Wudang, Taekwondo, sweeping a large area with a stick, and picking a line with a gun. I don't know what happened. Anyway, I practiced Chinese Kung Fu all night. The key is that when he was excited, he sat up from the bed and fought with his hands, making gusts of wind. It was not until his wife got up and slapped him down on the bed that he fell asleep.
"Good morning, senior brother," Lin Ruyan greeted senior brother early in the morning, and walked lightly to the seat like a breeze.
A day's work began like this.
Suddenly, senior brother turned around and asked Lin Ruyan:
"Ruyan, how is the gold finger board you designed for the customer last week? Has the customer made it in their factory? Has it been tested? What is the specific effect? Did you remind him that this board is a package of long and short gold fingers, and the short fingers cannot have leads when making the board."
"I reminded Engineer Zhang," Lin Ruyan answered readily.
Suddenly, Engineer Zhao came to Lin Ruyan like a ghost.
"Ruyan, how did you remind the customer?"
Lin Ruyan looked at Engineer Zhao's face, and her thoughts flew to a night three days ago. It was about eleven o'clock in the evening. Mr. Zhang, a customer, called and said, "The factory sent me an engineering problem a few days ago. Because this board has long and short gold fingers, the delivery date is urgent. In order to shorten the processing cycle, the board is now online. Please accept the residual short finger lead.
I didn't think much about it at the time and agreed to the factory's suggestion.
Now I think of this problem and want to ask how your company does it routinely. "
Lin Ruyan said at the time: "We usually remove the gold finger lead. The senior brother trained us before.
What is the role of the gold finger lead?
Because the gold finger needs to be plugged in and out, there are requirements for the thickness and hardness of gold. In order to meet this requirement, the gold finger area is usually processed by gold plating. Then to plate gold, there must be current passing through. This lead is led out from the front end of the gold finger, straight through the edge of the board, conducts current, and completes nickel and gold plating. After gold plating, the lead has completed its mission. Usually the factory will find a way to remove it, especially the lead of long and short gold fingers.
The conventional process flow of gold-plated fingers is as follows:
Why do PCB boards need long and
short gold fingers? The purpose of the packaging of long and short gold fingers is to ensure that there is a timing difference in power-on when the PCB board is plugged in and out. For example, when the gold finger is removed, the short finger will cut off the power supply first to play a protective role. Usually, when the gold finger is inserted, if the short finger is not inserted in place, the power supply will not be supplied to avoid power surges from damaging the gold finger product.
There are also some devices, such as the USB interface, where the lengths of the four pins are also different. The two long gold fingers on the left and right are connected to the power supply and the ground, and the two short fingers in the middle are responsible for data transmission. In this way, when the U disk is inserted into the machine, it is ensured that the power is turned on before data can be transmitted, which is also for the normal access and protection of the equipment. If the long and short gold fingers are made of equal length gold fingers, the protective effect will be lost and reliability problems will occur.
After listening to this, Mr. Zhang, the customer, suddenly realized, "So this is the function of the long and short gold fingers. Oh, I will remind the factory later not to make them equal length gold fingers."
As soon as Lin Ruyan finished talking about the communication process with the customer, the eldest brother hurriedly said:
"Then ask the customer if the changes have been made. The customer has been very busy recently and has been working overtime with us for this project. Although our company is not the one making the board, we still have to remind the customer not to forget about this matter, otherwise there will be problems later."
"Okay, then I'll call Engineer Zhang to confirm it. This board took Engineer Zhang and I a lot of effort."
Thinking of the hard times designing this board and the good cooperation of the customer Engineer Zhang, Lin Ruyan quickly picked up the phone, and Engineer Zhao stretched his neck and listened attentively.
"Mr. Zhang, how is your long and short gold finger project going? The short hand guide wire is not retained."
"Oh, Ruyan, don't mention it. After I asked you this question, I received a phone call and had other things to deal with in a hurry, so I forgot about it. It was several days later that I remembered it. When I went to find the factory, they reported that they had completed the board forming process, but the gold finger leads were not removed. I communicated with the factory and asked them to find a way to remove it. The factory said they have advanced technology and can remove it during the FQC inspection."
"What advanced technology, Mr. Zhang?" Lin Ruyan asked quickly.
"I don't know yet. The factory said it is confidential. Ruyan, I won't tell you yet. Maybe my goods have arrived. I'll go and take a look first and wait for my good news later." After
Lin Ruyan hung up the phone, her face was full of expectations, wondering what advanced technology the factory had to remove the gold finger guide wire.
The factory routinely uses a secondary etching process to lengthen and shorten the gold finger leads. Simply put, the circuit is etched for the first time, and the circuit part is covered with dry film or blue glue. The gold finger area is plated with gold through the gold-plated wire leads, and then all places are covered with dry film, leaving only the gold finger lead part exposed, and the leads are etched.
The process of etching the leads with chemical solutions requires adding a secondary dry film to protect the circuits and gold finger positions on the board, and then etching the leads. The process takes two more days. Now this factory has a special process, and it doesn't increase the time. It's not easy to think about it. Lin Ruyan also has a bit of inexplicable admiration for this PCB factory.
When a person works seriously, time will pass very quickly. In the blink of an eye, two hours passed.
Lin Ruyan stopped the work at hand and was about to get up and stretch when the phone rang.
She quickly picked up the phone.
"Ruyan, the factory broke the gold finger."
How did it break? The customer told a sad story in a low voice.
At that time, the factory made the long and short gold fingers of equal length and sent a picture to the customer. The customer saw that this was not okay. The long and short gold fingers were made of equal length and had no protection function. There might be problems, so the customer asked the factory to find a way to remove the gold finger guide wire. The
factory's process manager said proudly: "Mr. Zhang, don't worry, we will go to the gold finger to guide the wire. We have magical skills. We have a wonderful woman here. Go to the wire guide. With the help of God, you will be satisfied. "
The process manager was also very concerned. He arranged for a colleague on the night shift to handle this matter, so this amazing woman came on stage. This amazing woman
was indeed extraordinary. She picked out the gold finger lead with a knife, but she didn't grasp the timing when picking it. As a result, the lead was not picked out completely, and several knife pits were cut in front of the gold finger. When the customer inserted the gold finger into the slot, the gold finger went in, but the lead also curled up. It's not a big deal that the lead curled up, but it also brought up the gold finger. The gold finger curled up and fell off, and my board went to see its grandmother.
This... Lin Ruyan stood there in a daze.
Looking at the picture below, I can't help but think of a sentence, everything in the world can't stand the irradiation of a magnifying glass, and PCB boards are no exception.
The swordsmanship of the heroine is good, but it's a pity that she was a little heavy.
This is exactly:
The chivalrous woman shows her special trick at midnight,
picking up the wire under the lights.
The customer takes a board to test it urgently, and
all his fingers are curled up.
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