PCBA Tech - ​What are the technical standards for PCBA patches?

With the development of electronic products in the direction of small and thin, some electronic components with higher integration level and smaller pin spacing are more and more used in PCBA motherboards, and the requirements for PCBA patch processing are getting higher and higher. In order to ensure the welding quality of the product, the technical standards of PCBA patch must be strictly implemented.

With the development of electronic products in the direction of small and thin, some electronic components with higher integration level and smaller pin spacing are more and more used in PCBA motherboards, and the requirements for PCBA patch processing are getting higher and higher. In order to ensure the welding quality of the product, the technical standards of PCBA patch must be strictly implemented.

PCBA patch technical standards are:

1. PCBA patch quality inspection standards

The PCBA patch quality inspection standard is also known as the PCBA appearance inspection standard (IPC-A-610), as the global electronic assembly standard, the latest version is IPC-A-610F. The quality inspection standard defines the evaluation criteria and defects of welding quality and guides the PCBA processing process. It is the most basic quality inspection standard in electronic processing plants.

1. Definition of standards

[Accept Criterion]: Acceptance criteria include three conditions including ideal conditions, acceptance conditions, and rejection conditions.

[Ideal Condition] (Target Condition): This assembly situation is close to ideal and perfect assembly results. It can have good assembly reliability and is judged to be an ideal condition.

[Accept Condition] (Accept Condition): This assembly situation does not meet the near ideal condition, but it can maintain the reliability of the assembly, so it is regarded as a qualified condition and judged as an acceptable condition.

[Reject Condition]: This assembly situation does not meet the standard, which may affect the functionality of the product, but based on appearance factors to maintain the competitiveness of the company's products, it is judged as a rejection condition.

2. Definition of defects

[Critical Defect]: Refers to a defect that is sufficient to cause harm to the human body or machinery, or endanger the safety of life and property. It is called a fatal defect and is expressed in CR.

[Major Defect]: Refers to a defect that has lost the practicality of the product's essential function or caused a decrease in reliability. Product damage or malfunction is called a major defect, and it is represented by MA.

[Minor Defect]: Refers to the performance of a unit defect, which does not substantially reduce its practicability and can still achieve the desired purpose. Generally, it is the difference in appearance or mechanism assembly, expressed in MI.

Quality inspection standards can provide guidance for the operation of the production process and product quality assurance, and have important implications for improving welding quality.

2. PCBA patch management specifications

The PCBA patch process is more complicated, and any problem in any link will cause welding quality problems. Therefore, professional management standards are required in the processing process.

1. Comply with "Air Shower Regulations"

Wear the electrostatic clothes and hats according to the specifications, and then press the air shower door switch. Before opening the air shower room, enter the air shower room with your feet on the sticky mat to remove the dust. When you start the air shower, please turn your body according to the prompts and enter the air shower room. The number of wind showers cannot exceed 4 people at a time. The air shower time in the air shower room is set to 8 seconds, and the user shall not change it at will. After the air shower door has finished blowing, the door will open automatically. It is forbidden to pull the door to both sides by hand. The sticky mat in the air shower room is replaced twice a day, and it is recorded in the "sticky mat tear-off record sheet" if it is dirty, it can be replaced at any time to keep it clean.

2. Factory 7S management

The temperature of the workshop should be: 18-26 degree Celsius, humidity: 35-75%. Seiri, Seiton, Seiso, Seiketsu, Shitsuke, safety and conservation should be carried out. save). It can effectively solve the messy and disorderly state of the workplace, effectively improve personal mobility and quality, effectively improve the management of documents, data, and files, effectively improve work efficiency and team performance, and make the process simple, humanized, and standardized.

3. Standards for solder paste management

(1) Solder paste storage environment: refrigerating temperature 0 degree Celsius

(2) When the new solder paste is put into the warehouse, check whether the outer packaging is damaged. After unpacking the outer packaging, check whether there is an ice bag inside the incubator package. Visually check whether the solder paste can is damaged, whether the solder paste package is sealed and stored, and whether it has been opened. (3) Check whether the manufacturer's model and quantity on the solder paste tank are consistent with the receipt, and the difference between the date of solder paste entering the factory and the validity period shall not be less than 6 months.

(4) If there is any discrepancy in the inspection items, return to the warehouse and notify the purchaser to contact the manufacturer for return processing! (5) After the solder paste inspection is qualified, the batch of solder paste is numbered, and the "Solder Paste Control Label" is pasted on the outer wall of the solder paste tank for tracking control during use! And fill in the "Solder Paste Storage Record Form"

(6) For the placement of new solder paste, refer to the "Solder Paste Management Standards" to take out the previous batch of solder paste, and store the new solder paste in the refrigerator in order according to the serial number. The numbering sequence is placed from right to left and from inside to outside. Finally, put the remaining solder paste from the previous batch on the outside. The principle of receiving solder paste: use the opened solder paste first, and check whether the solder paste is within the validity period. The use of new solder paste follows the principle of from left to right and from outside to inside (the number of solder paste bottles ranges from small to large). After the solder paste is taken out, fill in the temperature recovery date and time recorder on the "Solder Paste Control Label", etc. Related Information.

(7) Requisition of solder paste: When the operator receives the solder paste, it is necessary to confirm whether the temperature of the solder paste meets four hours. Stir the solder paste. Stirring time: 5 minutes, 90% rotation speed. For the use of the solder paste mixer, refer to the "Specifications for the Use of Solder Paste Mixer"

(8) When receiving solder paste, it is necessary to fill in the "Solder Paste Receiving Record Form" and the "Solder Paste Control Label". The service life of the solder paste is 24 hours. If it is not used up after 24 hours, it will be scrapped. Fill in the "Solder Paste Rejection Record Form" and have a technician or engineer sign it for confirmation.

Three, PCBA patch electrostatic management standards

In the process of PCBA patch processing, static electricity has always been an important factor causing chip damage. Due to the easy generation of static electricity, it is necessary to strictly manage static electricity in electronic processing plants to avoid unnecessary losses to electronic components.

1. Equipment grounding

It is realized by connecting the metal wire with the grounding device, and the leakage current, static charge and lightning current that may be generated on the electrical equipment and other production equipment are introduced into the ground to avoid personal electric shock and possible fire accidents.

2. Wear electrostatic clothes, electrostatic shoes, and electrostatic bracelet; check that the electrostatic clothes and shoes pass the ESD test, and make a record.

3. Clean up all sources of static electricity in the work area, such as plastic bags, boxes, foam plastics or personal items (tea cups, hair clips, paper towels, key ornaments, glasses cases, etc.), and keep them at least 750px away from ESD sensitive components.

Four, PCBA patch cleaning standard

When the PCB is printed with solder paste, if there are continuous tin, little tin, no tin, more tin, tin tip or stay on the production line for more than one hour, the PCB needs to be cleaned and reprinted.

PCB cleaning steps:

1. Use a small scraper to scrape the solder paste on the PCB to the solder paste scrap box

2. Wet the dust-free wipe paper with plate washer water

3. Hold the PCB with your left hand, and wipe the surface of the PCB with a dust-free wipe with your right hand

4. After wiping, use *** to dry the PCB, and blow off the solder paste that is difficult to clean such as pinholes, screw holes, etc.

Precautions:

1. The bad PCB must be cleaned within one hour

2. To clean the PCB in the cleaning area, separate the PCB to be cleaned from the cleaned PCB

3. Make sure that the pinholes, screw holes, etc. are cleaned.

There are many PCBA patch processing links, and a small factor can easily cause product defects. Only by implementing strict PCBA patch technical standards can production be standardized and standardized, and product defects can be reduced.