Customer background: A trading company in Hong Kong with its own design team and its own small factory. We only do SMT in our factory, and their own workers produce the plug-in part. The end customer is in the Philippines.
Product background: control panel for household appliances. This product is a control panel for heating the footbath. Adjust the water temperature according to instructions, or control the constant temperature of the water.
Product features: a simple 2-layer board, in order to ensure smooth communication, the copper thickness is 3oz. The surface finish process is LF HASL. Look carefully at the design of the pcb to join the grid. Many of this client’s designs incorporate grid elements.
The benefits of grid:
- The current no longer goes straight! For the whole board, the current is taken along the nearest route. After adding the grid design, the current is taken at 90 degrees.
- Beautiful: make the PCB look no longer monotonous.
- Reduce capacitance distribution-less parallel area.
- The large ground area absorbs radio waves, which can reduce the load and save metal!
- Heat dissipation: provide thermal expansion space to prevent the PCB from deforming after being heated.
- The multi-layer board via hole is connected to the inner GND.
- Rule: Each mounting hole in the grid arrangement is designed on the intersection of the square grid.
- Withstand voltage: The layout of the components should be conducive to the heat dissipation of the heating components, and the distribution parameters between the components should be considered at high frequencies. The high and low voltages should be isolated. The isolation distance is related to the withstand voltage.
Problems encountered in production:
1. Solder balls:
Solder balls were found when the first three samples were produced, as shown below.
Many resistors and capacitors have such solder balls. The reason for our technical analysis is that there is no anti-tin bead treatment when the steel mesh is opened. As shown in the figure below. So when re-production batches, our company reopened a steel mesh. But because there is no silk screen layer, there is no way to judge which positions need to be treated with anti-tin bead. Therefore, after communicating with the customer, the customer agreed to provide the silk screen layer, but we do not need to actually print the silk screen when we produce the PCB. Let others have no way to follow suit.
2. Problems found by IQC:
After all the materials were prepared, our IQC found that there was a fuse holder that could not be installed in the PCB, as shown below:
But the sample customer is anxious to test, so we found the same specification products from the warehouse to confirm with the customer. Customers are surprised that we have such complete materials. In fact, our company has a warehouse dedicated to storing some conventional components, so centralized procurement can help customers save a lot of costs. The customer is also very funny, and soon changed Gerber’s design, as shown below Comparison before and after change.
3. The crystal is knocked off:
The second production was a small batch of 1,000 units, but the customer did get bad feedback after receiving it. As shown below.
Because the height of the crystal oscillator is much higher than other components, the violent transportation causes the crystal oscillator to fall off and even change its appearance. We have had other similar cases of violent transportation before. Therefore, our company recommends a customized blister box for mass production next time. The following picture shows how other products are in the blister box:
4. In the process of welding we found that there is a chip has air soldering phenomenon.
Air soldering: There is no tin or other factors between the part feet or lead pins and the solder pads, causing no bonding. Reference the picture below.
There are many reasons for this: component deviation, floating, PIN crooked, PIN warped, PIN offset. PCB PAD does not have tin printing, tin is small, component PIN oxidation, etc.; inspection method: from different directions (45 degrees) to confirm whether the parts foot and PCB PAD are soldered. One of the three samples was found, we did not find the reason, nor did we find similar phenomenon in the mass production. However, it has been recorded in our system that workers will focus on checking the situation of void welding when they ship.
Currently this project is mature and we are discussing larger production orders. The current details of communication are to improve efficiency. We may make auxiliary items such as AOI inspection tools in order to be more efficient and provide perfect products.
AOI fixture features: after the PCBA to test AOI (automatic optical inspection) process, and will more neat set of PCBA board to locate and transhipment, a must for transport vehicle positioning firmly have high requirements, also, corresponding production testing process after the completion of the PCBA board, need to remove the PCB, convenient preparation of PCBA board to achieve efficient production requirements.
Customers are very satisfied, thank you for our suggestions and cooperation since production. In fact, we at JY also want to thank our customers for their trust. While helping customers, we also help ourselves.
As a professional PCBA Manufacturer, we could supply one-stop service, including PCB board making, PCB Reverse Engineering, components sourcing, SMT assembly work, Program+Test, housing making, housing assembly…
We aslo have ERP system to manage every project from production file, quotation, purchase, production, delivery until service after it. Date will be found quickly and precise no matter when client wants to begin project.
If you have related projects, welcome to inquiry us to get free quotation.