Due to the needs of work, many people often participate in some large conferences or exhibitions. Under normal circumstances, the organizer will issue participants with badges, tickets or T-shirts with conference logos to facilitate admission management. However, badges are the most commonly used. Traditional badges are made of paper, plastic and strap. The plastic casing and straps can be recycled. However, after the conference or exhibition, the paper in the badge will be discarded. Every year, conferences around the world use a lot of paper, which is bad for the environment.
Our customer designed a control panel with smart badges. This product is mainly used in large exhibitions. In 2019, our company produced the first version of the product and used it in the exhibition in the country where the customer is located. The effect is remarkable. This time the need for improvement is the second edition.
In January, the customer designed version 2. He sent us the gerber and bom to us, and asked us to produce 5 sample boards first.
In the sample order, the customer required the board material was FR-4 with TG130-140, the surface finishing was Lead Free HASL. The thickness of board was 1.6mm, the color of solder mask was green, the silkscreen was white. It has 2 copper layers, the copper thickness was 1 OZ for each layer. When we finished the production of PCB, the customer told us that they wanted to produce several more PCB with ENIG finishing, white solder mask and black screen printing. It looks more beautiful, they want to compare the perform and outlook before mass production. So we produced some ENIG boards. The PCB production went well, but we encountered some problems in soldering.
Main difficulties and solutions
Before printing circuit board assembly, our IQC department checked all the components with PCB’s pads and DIP holes. They found that some components did not match the PCB well. Such as the USB—J3, in addition to the SMD pads, it also has 18 pins which need to be inserted and soldering. The 12 pins are 1.2mm in length in the middle and 1.6mm thick PCB, so these pins cannot be exposed from the other end after insertion. The technician in the IQC department immediately told the production engineer about this problem. After he checked it, he marked on the production flow scheme that these pins must be added more tin. He went to the welding team to inform the technicians pay attention to this component.
Besides, the holes of BZ1 is too big, and the wire is very thin. In addition, the holes for the battery box was designed to be too small, we pressed very hard to install the battery box on the board.
After the sample production, The IQC department first initiated the approval of production improvement on the DINGDING APP and reported the problems they found.
All the personnel involved in this project are approvers, including production engineer, welding team technician, QA department technician, production supervisor, procurement engineer, etc. When the approval comes to everyone, everyone detailed explained whether there is any problem in this step and explains in detail if there is a problem. The last approver is the sales of this project. Our sales summarized these problems and feedback our suggestions to the customer.
The customer had tested all the sample PCBA, they were performed well. They compared the two kinds of PCB, and finally decided to use the white ENIG PCB. For more stable performance, the customer made further modifications to the board, adding some capacitors and resistors. Considering our suggestions, they also adjusted the holes of the battery box and the BZ1.
Soon, we received their final design files. They provide the testing instruction and testing video this time. They hope that we can firstly produce 3pcs for testing, so as to ensure that there are no problems with the functions before starting mass production.
The testing steps as following:
1. Starting with no battery and no cable.
2. Power switch to the up position.
3. Attaching the AAA battery
4. Power switch to the down position.
5. Wait a few seconds.
6. 2 upper LEDs should blink blue.
7. Screen should say “Acceleration OK”.
8. Press each of the buttons on the right individually. The 2 upper LEDs turn purple.
9. Press left button, this makes the board vibrate.
10. After pressing all the buttons, the LEDs turn green and screen says “Buttons OK”.
11. Power switch to the up position. This will shut down the board.
12. Take out the AAA battery.
13. Plug type-C cable with power. Board should turn on, no need to check all buttons again, just make sure there is power.
14. When type-C is connected to a computer with Windows, a new drive should appear (like USB storage / thumb-drive / disk-on-key) named “CIRCUITPY”.
15. Power switch to the down position. This will shut down the board.
When we put the battery into the battery box, the board did not respond. We tried these three boards, all in the same situation. We used Type-C to power it again. After turning on the switch on the board, the two LEDs above the board began to blink. We tested steps 4 to 11, and the three boards all demonstrated functionality, as in the customer video and instructions.
After taking off the type-c cable, we tried the AAA battery again, but there was still no reaction.
And this time we felt the battery getting heat. The engineer initially suspected that it was because of poor soldering, or that the polarity of the battery silkscreen was reversed when the customer designed the PCB, so that caused a short circuit. We checked the soldering again and determined that there was no poor soldering. Then we removed one of the PCBA’s battery box and soldered in the opposite direction. We put the AAA battery again, but the PCBA still didn’t respond. The engineer scrutinized the components and the gerber. He found that the positive pole of the battery box was connected to the circuit below, which he suspected was the cause of the short circuit. He carefully cut in this position, testing the circuit with a multimeter. Then he put the battery to test again, the board can finally work properly.
We explained to customers in detail the test conditions of these 3 boards and our handling methods. Customers are very grateful to us because they are in urgent need of these new versions of smart badges for the coming exhibition. Time is not enough to modify the design and produce another batch of PCB. We found the solution in short time, which can help them to save time and cost.
After getting confirmation from the customer, we arranged a technician to cut this position of each PCB and test the circuit with a multimeter. Then we immediately arranged mass assembly. When the QA department checked all the soldering quality after assembly, the technicians tested the control boards. They all work very well. We shared the test video with our customers and they were very excited.
After the production of this batch of PCBA was completed, the test technician initiated the DINGDING approval. Everyone summarized the opinions. Finally, the data staff will upload the summary to our ERP system to help us check before repeat orders are generated.
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