The various stages in the PCB assembly process consist of (1) adding solder paste to the board, (2) picking and placing components, (3) soldering, (4) inspectioning and (5) testing; these processes need to be monitored to ensure the high quality of the product.
1- Solder paste phase
The solder paste is a paste of small grains of solder mixed with flux, which can be deposited into place in a process that is very similar to some printing processes.
Prior to the addition of the components to a board, the solder paste needs to be added to particular areas of it using a solder screen. Typically these areas are the component pads. By placing the solder screen directly onto the board in the correct position, a runner is moved across the screen squeezing a small amount of solder paste through the holes in the screen and onto the board. As the solder screen is generated from the printed circuit board files, it has holes corresponding to the solder pads, ensuring the correct localization.
During the process, the amount of deposited solder must be continuously controlled to guarantee the right amount in the resulting joints.
2- Pick and place phase
During this part of the assembly process, the board with the added solder paste is located in the pick and place system, which is loaded with reels of components. This system picks the components from the reels or other dispensers, and exploiting the tension of the solder paste, places them onto the correct position on the board, providing its stability.
In some assembly processes, the pick and place systems add small dots of glue to secure the components to the board. However this is normally done only if the board has to be wave soldered. The disadvantage of the process is that any repair become far more difficult by the presence of the glue, although some glues are designed to degrade during the soldering process. The components' position information required to programme the pick and place system is derived from the printed circuit board design, simplifying the assembly process.
The next stage of the production process is to pass the assembled board through the soldering machine. Although some boards could be passed through a wave soldering machine, this process is not widely used for surface mount components. Rather than using wave soldering, reflow soldering technique is used more widely.
Machines are available to inspect boards joints detecting poor joints, misplaced components, and under some instances the wrong component.
Manual inspection is not an option for surface mount boards consisting of hundred or more components; instead automatic optical inspection is a far more viable solution.
To ensure that the manufacturing process is well running, it is necessary to monitor the outputs. This is achieved by investigating any detected failures. HTS has the capabilty to design test's routines from static to dynamics, up to functional tests able to detect faults in all different parts of the board. It is possible to test the entire production, or a sample of the mass production.
Complete automated assembly lines for PCBs consist of various functional tests, product marking, traceability, packing and delivering of complete devices.These lines offer high reliability, repeatability, quality and throughput. HTS offers consistent high quality and absolute reliability of its products.
Production covers the following areas:
- Prototype production
- THT assembly
- SMD assembly
- Package: from 0201 to 01005, BGA, pitch 03
- Assembly capacity: 30k components per hour
- Reflow soldering processes
- Wave soldering equipment
- Burn-in test
- X-Ray inspection