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PCB factory china: PCB bonding process

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Popularity:756Dated :03-16-2022 06:28【big well Small

PCB factory china tells you what is PCB bonding process:

1. Cleaning the PCB

Scrub the oil, dust, and oxide layer on the circuit board position, and then use a brush to clean the wiping position, or blow it with an air gun.

2. Drip Adhesive

The amount of glue drops is moderate, the number of glue points is 4, and the four corners are evenly distributed; the bonding glue is strictly prohibited from contaminating the pad.

3. Die Attach (Solid Die)

When using a vacuum suction pen, the suction nozzle must be flat to avoid scratching the wafer surface. Check the orientation of the wafer, and it must be "smooth and positive" when sticking to the PCB: flat, the wafer and the PCB are closely attached in parallel with no voids; stable, the wafer and the PCB board are not easy to fall off during the entire process; positive, the wafer and the PCB are reserved in place Positive paste, can not be deflected, pay attention to the wafer direction should not be reversed phenomenon.

4. Bond Line

Bonding's PCB board has passed the bonding tensile test: 1.0 line is greater than or equal to 3.5G, 1.25 line is greater than or equal to 4.5G.

Standard aluminum wire with a fixed melting point: the wire tail is greater than or equal to 0.3 times the wire diameter, and less than or equal to 1.5 times the wire diameter. The shape of the aluminum wire solder joint is oval.

Solder joint length: greater than or equal to 1.5 times the wire diameter, less than or equal to 5.0 times the wire diameter.

The width of the solder joint: greater than or equal to 1.2 times the wire diameter, less than or equal to 3.0 times the wire diameter.

During the bonding process, it should be handled with care, and the point should be accurate. The operator should use a microscope to observe the bonding process to see if there are any bad phenomena such as broken bonding, winding, offset, hot and cold welding, and aluminum lifting. To notify the relevant technical personnel to solve in time.

Before the official production, there must be a first inspection by a special person to check whether there is a state error, a lack of state, a lack of state and other phenomena. In the production process, a special person must check its correctness at regular intervals (up to 2 hours).

5. Plastic Closures

Before installing the plastic ring on the chip, check the regularity of the plastic ring to ensure that the center of the plastic ring is square without obvious distortion. When installing, ensure that the bottom of the plastic ring is closely attached to the surface of the chip, and the photosensitive area in the center of the chip is not blocked. .

When dispensing, the black glue should completely cover the sun circle of the PCB board and the aluminum wire of the bonding chip, and it should not be exposed, and the black glue should not seal the PCB sun circle. into the wafer.

During the dispensing process, the needle tip or swab should not touch the surface of the wafer in the plastic ring and the bonding wire.

The drying temperature is strictly controlled: the preheating temperature is 120±5 degrees Celsius, and the time is 1.5-3.0 minutes; the drying temperature is 140±5 degrees Celsius, and the time is 40-60 minutes.

The surface of the black glue after drying shall not have pores or uncured appearance, and the height of the black glue shall not be higher than the plastic ring.

6. Test

A combination of multiple testing methods:

A. Manual visual inspection;

B. Bonding machine automatic welding wire quality inspection;

C. Automatic Optical Image Analysis (AOI) X-ray analysis to check the quality of inner solder joints.

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