The differences between contact dispensing and non-contact dispensing are significant in the dispensing process, mainly reflected in the following aspects:
---
### **1. Working Principles**
#### **Contact Dispensing**
- **Working Method**: The needle approaches the target component, relying on contact between the dispensing needle and the target to dispense the liquid.
- **Technical Characteristics**:
1. Equipped with high-precision height sensors to accurately control the needle's descent and ascent.
2. During the dispensing process, the liquid makes contact with the target surface and is allowed to spread over time. Then, the needle retracts upward, separating the liquid from the needle due to the adhesive force between the liquid and the substrate, forming a dispensing dot.
#### **Non-Contact Dispensing (Jet Dispensing)**
- **Working Method**: Liquid is dispensed onto the target using a nozzle without physical contact.
- **Technical Characteristics**:
1. Uses high fluid momentum generated within the jet valve to spray liquid directly, without relying on surface tension.
2. Does not require the dispensing valve to move along the Z-axis, thus avoiding any physical impact or damage to the workpiece.
---
### **2. Application Scenarios and Advantages**
#### **Contact Dispensing**
- **Application Scenarios**:
1. Suitable for a wide range of liquids.
2. Cost-effective scenarios.
- **Advantages**:
1. Relatively low cost.
2. Strong adaptability to various liquids, including different viscosities.
#### **Non-Contact Dispensing**
- **Application Scenarios**:
1. Ideal for high-speed dispensing of low- to medium-viscosity liquids.
2. Suitable for dispensing in areas with needle interference or on non-planar surfaces.
- **Advantages**:
1. Higher efficiency and precision, significantly improving dispensing speed.
2. High jetting frequency.
3. No physical contact ensures dispensing in confined spaces without contaminating or damaging the workpiece.
---
### **3. Technical Categories**
Non-contact dispensing can be divided into the following types based on the driving mechanism:
1. **Pneumatic Jet Dispensing Valve**: Uses pneumatic principles to generate jetting force.
2. **Piezoelectric Jet Dispensing Valve**: Utilizes the bidirectional conversion principle of piezoelectric ceramics, ejecting liquid through high-frequency vibration, offering high precision and efficiency.
---
### **4. Conclusion**
Contact dispensing and non-contact dispensing have distinct features and application scenarios:
- **Contact Dispensing**: Best suited for applications requiring cost control or handling a wide variety of liquids, particularly in traditional industrial settings.
- **Non-Contact Dispensing**: Excels in high-efficiency, high-precision manufacturing scenarios, especially for applications involving electronics integration, semiconductor packaging, and similar fields.
As technology continues to evolve, non-contact dispensing is gradually becoming the standard method in high-tech fields like electronics, semiconductor packaging, and flat panel display assembly, driving the industrial manufacturing process toward greater efficiency and precision.