Several notes on BGA patch processing

In the SMT patch process of BGA and small-sized components (such as 0402/0201/01005), it is very important to ensure speed and quality.

Several notes on BGA patch processing

1. The necessity of process edge and MARK point

The role of process edge, PCB boards with BGA and small-sized components need to reserve 5mm process edge on the board edge.

This is because of the accuracy of pad printing and mounting: if there is no process edge, the pad within 4mm from the board edge cannot be soldered and mounted. Such design defects will cause the components to be unable to be installed correctly, and they must be manually re-welded, especially for 0201 components. The reliability of manual re-welding is obviously not as good as equipment mounting and welding.

Production efficiency: The process edge can help the machine position, ensuring that each component can be accurately mounted at the predetermined position, thereby improving production efficiency and patch quality.

Importance of MARK points

MARK points are the key to machine vision recognition and positioning:

Precise positioning: The equipment relies on MARK points for precise positioning to ensure high precision of printing and patch. If the PCB does not have MARK points, only TP points or pads can be used as substitutes. These substitute points are usually different from MARK points, which can easily lead to insufficient patch accuracy and may cause BGA offset short circuit or 0201 component offset. Therefore, engineers need to pay close attention online and try to improve accuracy manually.

2. Importance of complete information

Information preparation

Before processing all SMT boards, the SMT factory must sort out the equipment processing procedures and first-piece inspection drawings based on the information provided by the customer. The more complete the information provided by the customer, the shorter the factory preparation time, the faster the delivery time, and the more guaranteed the quality.

Impact of customer information

The bit number map provided by the customer this time only has bit numbers but no specifications, and cannot be directly used for first-piece inspection. In order to ensure production quality, the SMT factory needs to manually fill in the specifications of each part on the bit number map, and this process takes at least 24 working hours. In view of the tight delivery schedule, this step is omitted this time, and the production is carried out by strengthening the station table check.

3. Requirements for material management

The RC components in the SMT sample require reel-mounted materials. Reel-mounted materials not only have clear identification labels, which are convenient for inventory and loading, but also significantly improve loading efficiency.

Risks of piece-by-piece materials

The RC components provided in pieces have the following problems and risks:

Mangled identification: Materials without reels usually have only brief handwritten specifications, which can easily lead to inventory and loading errors.

Low loading efficiency: The loading time of piece-by-piece materials is three times that of reel-mounted materials.

Material head loss: Each time the material is loaded, a 5cm long material head is required, resulting in material loss, which may cause the tail number board to be short of material and unable to be shipped. In order to solve this problem, it is necessary to wait for the material to be replenished and perform manual welding, which affects the quality and delivery time.

In order to ensure that the SMT patch of the BGA board is fast and high-quality, it is necessary to:

1. Reserve the process edge: ensure that the pad within 4mm from the board edge can be used for solder paste printing and patching.

2. Set the MARK point: ensure that the machine can accurately identify and locate, and ensure the patch accuracy.

3. Provide complete information: customers need to provide detailed position number and specification information to reduce the time of manual specification filling, and ensure quality and delivery.

4. Use reels to load components: avoid production problems caused by confusing identification and low loading efficiency.

Through the above methods, SMT factories can effectively improve production efficiency, ensure patch quality, and achieve fast and good BGA board patch processing.

Follow PCBAMake to get more technical knowledge about PCB proofing, SMT patch, and PCBA processing!