PCB Tech - How to choose a PCBA assembly manufacturer?

How to choose a PCBA assembly manufacturer? The introduction is as follows:

1./How is the machine condition (pick-and-place and reflow oven)

What is the accuracy of the old and new data? How much data can be processed by yourself. They are Chinese or Japanese machines. These parameters are important because they affect productivity and output. If the machines are not very precise, they will not be able to handle the smallest component packaging technologies, such as SMD type layouts.

Some old machines are not well maintained and used in production. For example, they may reduce the production speed due to defects. For example, the placement machine is not precise enough, or if it keeps breaking down, then production will slow down in one way or another, because you will not be able to guarantee a continuous PCB production process.

I used to have some PCBs that often had machine failures, resulting in several productions because they could not postpone work. I also saw some idol worship PCB components. The person buying the second-hand machine will not place the parts accurately in the correct X/y position. Operators need to put the components back in place, thereby increasing production time and production delays. Manually replacing a component with only 10,000 PCBs on hand can cause a long delay.

2. What quality inspection did they complete

As we all know, quality control is essential for considering production operations in China. PCB assembly operations are available, but not all suppliers are aware of most of their 2-3 quality control operations. Visual first person: If the component is welded, then perform verification visual observation, which is the most frequent way for the operator to find any abnormal component configuration. This is definitely a product that every PCB factory must produce.

AOI Vision Machine: Second, speed up the pre-processing of visual quality control to achieve more reliable automatic optical quality control. Normally, this is a comparison of using a camera to visually identify the correct position and the correct component on the PCB. It usually makes the image contrast.

Functional test: Functional test verifies the functionality of the PCB. This is usually generated by the power supply circuit, through the generated input, through observation and analysis of the generated PCB output.

3. How many production lines do they have

If you want to make an important PCBA proof, how to make it quickly after delivery is necessary. If they want to manage multiple orders at the same time, and then run multiple production lines at the same time, it is an advantage to ensure that they can run all orders faster by running some products in parallel. Choose your PCBA partner and make sure they have a junction box;

4./They have standard passive component inventory

In most cases, the PCB will retain some common components such as resistors, capacitors, diodes, transistors and inductors. This may help to avoid giving yourself and keeping an inventory count. They accept small orders and any mass production before R&D; D needs to make some PCBA templates, which is equivalent to making some very small products. Before doing this, you need to risk releasing an unstable product.

You can work with two different PCB suppliers: proofing and mass production, but I don't recommend this because of the consistency of the process. It is best to have a continuous product development phase and manufacturing phase. So, you better make sure that they can do some small and large runs, not just for them to track production in the future.

6./How do they use solder paste

Is this machine manual or automatic? Since the speed of human error is usually higher than the speed of machine error, it is best to use automatic printing

7./The position of unqualified workers' hands

Sometimes, it is not possible to use the placement machine to place a specific type of component (for example, if the component has a very special shape and the suction head cannot grasp it, or if the component is not sold on the board or tray), the operator must place the PCB pad The components were manually reflowed before. You need to ensure that these operators are properly trained so that they can manufacture small parts. Sometimes the score is too small and you need to have the right skills (the microscope will be placed in the right place).

8./They separate lead and lead-free production lines

If you use solder PCBs to assemble specific market lead (because it is usually cheaper to use solder lead), if you need lead-free solder, you need to make sure they are not properly mixed. Severe PCB will physically isolate the production line, and even lead-containing dust will pollute lead-free production. I have seen wall or net separation production lines of some PCB manufacturers.

9./What is the defective rate

How many PCBs 100 will be produced after rework. Yield is an important consideration because it directly affects delivery time. Most suppliers will tell you that their defects are less than 1%, but the actual situation is often different. What is the cost ratio?

10./How do they store materials

The air in China is already very humid, sometimes very hot. When you release components or PCBs, you will find that they are usually vacuum sealed and contain silicone to dehumidify. The reason is: oxidation.