Solder Paste Jetting Process Introduction

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The jetting process is an emerging non-contact solder paste deposition technology that utilizes a high-speed jetting valve to spray tiny solder paste droplets onto the pads of printed circuit boards (PCBs) to achieve on-demand, precise deposition of solder paste. The principle of the jetting process is similar to that of an inkjet printer. By controlling the movement of the nozzle and the frequency of the jetting, it is possible to achieve high-speed, high-precision and highly flexible solder paste deposition.

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Figure 1. Solder paste jetting process

There are two main types of traditional solder paste application processes: stencil printing and syringe dispensing. Stencil printing requires the use of stencil templates, and the printing process time is long, low flexibility, and is only suitable for mass production; while syringe dispensing requires the use of air pressure control, low efficiency, the amount of solder paste is not easy to control, and high cost. Compared with these two processes, the jetting process of solder paste has the following advantages:

1. It can realize smaller solder paste points and adapt to finer pad spacing to meet the needs of microelectronic packaging.

2. Higher solder paste deposition speeds for improved productivity.

3. More flexible solder paste deposition methods, such as in the cavity, the top of the component or uneven surface for solder paste deposition.

4. Saving the amount of solder paste, reducing production cost and environmental pollution.

5. Avoid some problems in stencil printing process, such as uneven printing of solder paste, solder paste residue and cleaning, stencil replacement and maintenance.

Requirements for solder paste in the jetting process

1. Good sphericity and narrow particle size distribution of solder powder

The use of solder powders with good sphericity and a narrow particle size distribution is essential in the jetting process. Good sphericity means that the solder particles have a regular spherical shape, which is essential to ensure smooth paste injection. The regular spherical shape of the particles reduces the risk of needle clogging and ensures the continuous and stable operation of the production line. In addition, the narrow particle size distribution helps to improve the uniformity of the solder powder, ensuring that the size of the solder particles varies little throughout the jetting process, thus improving the consistency and controllability of the solder paste.

2. Good Thixotropy, Rheology

Thixotropy refers to the application of force or pressure, the paste can quickly change its shape to adapt to the movement of the spray head and change. Rheology, on the other hand, refers to the paste's ability to flow when force is applied. Good performance of these two properties helps to ensure that the solder paste can be sprayed smoothly and uniformly during the production process, and better control of the spray volume, thus improving production efficiency.

3. Moderate viscosity properties and good wettability

Viscosity is a measure of the fluidity of a liquid, and moderate viscosity characteristics are essential to maintain the dot shape of the paste. Too high a viscosity may cause the paste to be difficult to distribute uniformly during the jetting process, while too low a viscosity may lead to an unstable paste point shape. Good wettability means that the solder paste adheres effectively to the substrate and solder joints, eliminating defects such as pull-tip. By regulating the viscosity characteristics and wettability of the solder paste, the jetting process can be optimized to ensure the stability and consistency of solder quality.

Fitech jetting solder paste

Jetting solder paste produced by Fitech is made of solder powder with good sphericity and uniform particle size distribution, smooth tin down without blocking the needle, moderate viscosity, excellent wetting performance, suitable for constructing complex substrates as well as the TFT process of solder paste coating, which can realize the point, line and surface of the solder paste pattern. Welcome to call us for more information.