PCBA Tech - Process materials and throwing materials used in SMT

Process materials used in SMT patch processing

SMT processing materials play a vital role in the quality and production efficiency of SMT patch processing, and are one of the foundations of SMT patch processing. When designing smt processing and establishing a production line, appropriate process materials must be selected according to the process flow and process requirements. The smt processing materials include solder, solder paste, adhesives and other welding and patch materials, as well as flux, cleaning agents, heat conversion media and other process materials. Today, SMT manufacturers will introduce the main functions of assembly process materials.

(1) Solder and solder paste

Solder is an important structural material in the surface assembly process. Different types of solder are used in different applications, which are used to connect the metal surface of the welded object and form a solder joint. Reflow soldering uses solder paste, which is a soldering material, and at the same time can use its viscosity to pre-fix the SMC/SMD.

(2) Flux

Flux is an important process material in surface assembly. It is one of the key factors that affect the quality of welding. It is needed in various welding processes, and its main function is to assist welding.

(3) Adhesive

Adhesive is the bonding material in surface assembly. When using the wave soldering process, an adhesive is generally used to pre-fix the components on the PCB. When assembling SMD on both sides of the PCB, even if reflow soldering is used, adhesive is often applied to the center of the PCB land pattern to strengthen the fixation of the SMD and prevent the SMD from shifting and falling during the assembly operation.

(4) Cleaning agent

The cleaning agent is used in surface assembly to clean the residue left on the SMA after the soldering process. Under the current technical conditions, cleaning is still an indispensable part of the surface mount process, and solvent cleaning is the most effective cleaning method.

The smt processing material is the basis of the surface mount process, and the corresponding assembly process materials are selected for different assembly processes and assembly procedures. Sometimes in the same assembly process, the materials used are also different due to different subsequent processes or different assembly methods.

Reasons for the throwing of the placement machine in SMT placement processing

In the process of SMT production and processing, it is difficult to avoid the problem of throwing materials from the placement machine. The so-called throwing means that the placement machine does not paste after sucking the material during production, but throws the material into the throwing box or other places, or performs one of the above throwing actions without sucking the material. Throwing causes material loss, prolongs production time, reduces production efficiency, and raises production costs. In order to optimize production efficiency and reduce costs, it is necessary to solve the problem of high throwing rate. The main reasons and countermeasures of throwing materials:

Reason 1: The suction nozzle problem, the suction nozzle is deformed, clogged, or damaged, causing insufficient air pressure and air leakage, resulting in unacceptable suction, incorrect retrieving, failure to identify and throwing.

Countermeasure: Clean and replace the nozzle;

Reason 2: Recognition system problem, poor vision, dirty vision or laser lens, debris interfering with recognition, improper selection of recognition light source and insufficient intensity and grayscale, and the recognition system may be broken.

Countermeasures: Clean and wipe the surface of the recognition system, keep it clean and free of debris, etc., adjust the intensity and gray level of the light source, and replace the components of the recognition system;

Reason 3: Position problem, the reclaiming is not in the center of the material, the reclaiming height is not correct (usually press down 0.05MM after touching the part), resulting in deviation, the reclaiming is not correct, there is an offset, and the recognition is followed. The data parameters do not match and are discarded as invalid materials by the recognition system.

Countermeasure: Adjust the reclaiming position; Reason 4: Vacuum problem, insufficient air pressure, unsmooth passage of the vacuum tube, guide material blocking the vacuum passage, or vacuum leakage, which causes insufficient air pressure and cannot be reclaimed, or it is posted after picking it up. Falling on the way.

Countermeasures: adjust the air pressure steeply to the required air pressure value of the equipment (such as 0.5~~0.6Mpa--YAMAHA placement machine), clean the air pressure pipeline, and repair the leaking air path;

Reason 5: Program problem. The component parameters in the edited program are not set correctly, and they do not match the actual size, brightness and other parameters of the incoming material, which will cause the recognition to fail and be discarded. Countermeasures: modify the component parameters, search for the best parameter settings of the component;

Reason 6: Incoming material problems, irregular incoming materials, unqualified products such as pin oxidation.

Countermeasure: IQC will do a good job of incoming material inspection, and contact the component supplier; Reason 7: Feeder problem, feeder position deformation, feeder poor feeding (feeder ratchet gear is damaged, the material belt hole is not stuck in the supply On the ratchet gear of the feeder, there is a foreign body under the feeder, the spring is aging, or the electrical failure), which causes the material to be thrown due to the failure of the reclaiming or the poor reclaiming, and the feeder is damaged.

Countermeasures: adjust the feeder, clean the feeder platform, replace damaged parts or feeders; when there is a throw-away phenomenon, you can first ask the on-site personnel, through the description, and then directly find the problem based on observation and analysis. It can more effectively identify problems and solve them, and at the same time improve SMT production efficiency.