PCB Technical - ​SMT patch dispensing and cost calculation method

1. Dispensing method for SMT patch processing

Dispensing method for SMT patch processing: Dispensing is to use compressed air to dispense red glue on the substrate through an extraordinary dispensing head. The size and number of bonding points are controlled by time, pressure tube diameter and other parameters. The glue dispenser has flexible functions. For different parts, you can use different glue heads, set the parameters to change, and you can also change the shape and number of glue dots to achieve the effect. It has the advantages of convenience, flexibility and stability. The disadvantage is that it is easy to produce wire drawing and air bubbles. We can adjust operating parameters, speed, time, air pressure and temperature to minimize these defects.

The needle-rolling method of patch processing is to immerse an extraordinary needle-like film in a shallow rubber plate. Each needle has a joint. When the glue dot touches the substrate, it will separate from the needle. The amount of glue can be changed according to the shape and diameter of the needle. Curing temperature: 100°C, 120°C, 150°C, curing time: 5 minutes, 150 seconds, 60 seconds. Typical curing conditions. Note:

1. The higher the curing temperature of the patch process, the longer the curing time and the stronger the bonding strength.

2. Since the temperature of the PCB adhesive varies with the size and mounting position of the substrate assembly, we recommend finding the most suitable hardening conditions. Red glue storage: store at room temperature for 7 days, store below 5°C for more than 6 months, store at 5-25°C.

The size and volume of the patch components used in SMT patch processing are much smaller than that of traditional plug-ins, and generally can be reduced by 60%-70% or 90%. The weight is reduced by 60%-90%. This can meet the growing needs of miniaturization of electronic products. SMT patch processing components are usually lead-free or short leads, which reduces the distribution parameters of the circuit, thereby reducing radio frequency interference.

Second, the method of calculating the cost of SMT patch processing

SMT chip processing is widely used in the electronics manufacturing industry, so the specific chip processing price and how to calculate the cost are still an unfamiliar field to many people.

SMT chip processing is widely used in the electronics manufacturing industry, so the specific chip processing price and how to calculate the cost are still an unfamiliar field to many people. After all, chip processing is not the pricing of finished products, and the connection between the two is more complicated, so the calculation method of chip processing cost is affected by many factors. Therefore, this article will introduce you to the calculation method of SMT chip processing cost.

At present, the main products of SMT are: lead-free soldering process, lead soldering process and red glue soldering process. And the point calculation method is very similar, but many users know little about the calculation of patch points and how to calculate the cost.

Some companies count one pad as one point, but have two welds as one point. This article takes pad computing as an example. All you have to do is to calculate the number of pads on the printed circuit board, but when you encounter some special components, such as inductors, large capacitors, integrated circuits, etc., you need to calculate the rated power. The specific experience is as follows: If the inductance can be calculated by 10 points, the integrated circuit can be discounted by the number of pins (such as a 40-pin integrated circuit, calculated by 20 points). According to the above method, the total number of solder joints of the entire PCB can be easily calculated.

PCB solder joint unit price: the current solder joint unit price is 0.008-0.03 yuan\/solder joint, depending on the following conditions:

1. The unit price is based on the process

a. The processing price of chip lead solder paste is lower;

b. The processing cost of chip lead solder paste is relatively high;

c. SMD red glue environmentally friendly solder paste processing cost is lower;

d. The processing cost of the red glue patch solder paste plus the high cost makes the process more troublesome.

2. According to the order quantity

a. 3-20 pieces of ordinary SMT chips are sampled and processed, and the engineering fee is not calculated by multiplying the number of points by the unit price;

b. For small-batch SMT chip processing and production of less than 1,000 pieces, the start-up fee is multiplied by the unit price;

c. Batch placement processing is calculated by multiplying the number of points by the unit price.

3. According to the difficulty of the board

a. According to single-sided and double-sided classification, single-sided patch processing speed is faster, double-sided patch processing requires two turns, which is more costly;

b. According to the precision, more precise chip processing, such as bga and other high-density integrated circuit board solder paste is expensive and costly;

c. According to the density of the placement components, the more midpoints of the same size PCB, the higher the efficiency, the shorter the coordinate stroke of the placement machine, and the faster the processing speed of the placement machine.

4. Start-up fee.

If the single batch processing fee is less than 1,000 yuan, it is a small batch processing order. For small batch SMT chip processing orders, after counting the points, you will see the type of board components, the debugging time of the chip machine, and the starting fee of 400-2000 yuan for the different difficulties of making the first piece.

5. Proofing fee

SMT patch processing order An SMT patch proofing order is within 100 sheets. The difficulty of the board, the time of making the program, and the start-up time are different, and the engineering cost ranges from 800 yuan to 3,000 yuan.

6. Wire mesh fee

According to the PCB size, open different types of steel mesh. According to the accuracy of PCBA chip, we choose open electrolytic polished steel wire mesh or ordinary steel wire mesh. The cost of different types of steel mesh is about 120-350. Of course, customers can also provide their own steel mesh.