You must know that pcb board manufacturing and foreign trade personnel have this knowledge. PCB circuit board surface copper is basically the world's copper plate, and the thickness of the copper foil will affect the bonding strength between the copper foil and the substrate.
PADS ranges from ounces (35000 ounces) to fibers, dielectric and capacitors, then to thin film resistors, and finally to copper foil on PCB boards. Generally, PCB factories can produce good boards called PC - "substrates".
Finally, there is the testing fixture, which is a testing board designed specifically for the formal process of SMT installation, plugins, and assembly stages.

The trend of BGA packaging technology is becoming faster and faster, but there are still many shortcomings, mainly reflected in the following aspects.
Compared to the area of integrated circuit chips, ICs with large ball spacing have a larger BGA volume than pins.
Electronic technology has entered a stage of rapid development, and people's requirements for electronic products are becoming increasingly high. This also requires some special requirements that microelectronic integrated circuits must have to achieve their functions. Microelectronic integrated circuits are one of the pillars of information electronic systems and also one of the fundamental core components of microelectronic chips. In the early days, electronic devices were directly affected by voltage.
In recent years, the demand for electronic information products has sharply increased, and the output of the integrated circuit chip market has been continuously increasing. Integrated circuit products, represented by ultra large scale integrated circuits, have continuously improved in scale and performance, and performance. In order to reach the advanced level, the design of integrated circuit design (fab), processing technology and the ability to stack layer grids have become extremely important. The specific process of design can be divided into four steps: the final end of the design phase and the end of production, two steps: sequentially completing the integrated circuit manufacturing process.