High-Power Rectangular Spot Laser Soldering for SMD Capacitors with Solder Paste

High-Power Rectangular Spot Laser Soldering for SMD Capacitors with Solder Paste

Rectangular Spot High-Power Chip Capacitor Solder Paste Laser Welding

This is an advanced welding technology applied in the field of electronic manufacturing. Songsheng Optoelectronics will provide a detailed introduction for everyone - let's take a closer look!

Illustration of Different Types of SMD Capacitors

Technical Characteristics

Localized Heating and Stress Control: The rectangular spot enables zonal heating that exclusively targets the soldering area with minimal thermal impact on adjacent non-soldering zones. This eliminates the need for whole-component heating, significantly reducing welding thermal stress. Particularly crucial for heat-sensitive components like chip capacitors, this feature mitigates risks of component damage or performance degradation caused by thermal stress.

Multi-point Simultaneous Welding and High-efficiency Production: The rectangular spot's expansive and uniformly distributed energy coverage facilitates concurrent soldering of multiple joints. Compared to conventional sequential soldering methods, this dramatically enhances production efficiency. Especially suitable for multi-joint applications like chip capacitor arrays, it enables high-volume soldering within shortened cycle times to meet mass production demands.

High-precision Positioning and Alignment: Typically integrated with high-accuracy coaxial CCD positioning systems, it provides clear joint visualization and real-time coordinate calibration. This ensures precise alignment of the rectangular spot between chip capacitor electrodes and PCB pads, maintaining soldering accuracy even for miniature components (down to 0201 size) and densely arranged joints, thereby minimizing soldering deviations and defect rates. 

Superior Temperature Control: incorporated with real-time temperature feedback systems, it monitors soldering zone temperature with high precision (e.g., ±5℃ control). By precisely regulating laser energy and duration, it ensures optimal solder paste melting and solidification temperatures guaranteeing consistent joint quality while preventing solder splashing (from overheating )  or cold joints (from insufficient temperature).

Welding Process

Preparation：First, clean the clip capacitors and circuit boards to remove surface contaminants such as oils, dust, oxides, ensuring welding quality. Then, select an appropriate rectangular spot size and shape based on the capacitor dimensions, pitch and circuit board layout, and adjust the laser welding systems parameters including laser power ,and pulse frequency. Simultaneously, apply solder paste evenly onto the circuit board pads using precision dispensing equipment ,with the amount carefully controlled-excessive or insufficient solder paste may adversely affect the welding results.

Welding Process：Position the circuit board with mounted capacitors on the laser welding stage, and perform precise alignment via the CCD positioning system to ensure the rectangular spot accurately covers the target welding area. Activate the laser welding system, where the high-power laser beam irradiates the solder paste. The paste rapidly absorbs laser energy, heating above its melting point to liquefy. The molten soler flows under surface tension and gravity to fill the gaps between capacitor electrodes and pads. Throughout welding, the temperature feedback system monitors in real-time to maintain the welding zone temperature within preset parameters.

Cooling and Solidification: After laser irradiation ceases, the molten solder begins cooling and solidifying to form robust solder joints that reliably connect the chip capacitors to the circuit board. The cooling process must be free from external disturbances to ensure stable joint morphology and performance. 

Equipment Composition

Laser welding head: Comprising components such as a real-time adjustable spot size lens assembly and temperature measurement system, it is responsible for generating and focusing the laser beam to form a rectangular spot while monitoring the temperature of the welding area. 

Multi-axis robot: Used to precisely control the position and motion trajectory of the welding head, enabling welding of solder joints at various locations and with different shapes. 

Temperature feedback system: Monitors the temperature of the welding area in real-time and feeds the temperature data back to the control system to promptly adjust laser energy, ensuring welding quality and yield rate. 

CCD coaxial positioning system: Provides clear images of solder joints for precise alignment and real-time monitoring of the welding process, correcting deviations caused by part dimensions and positional inaccuracies. 

Laser: Typically a constant-temperature semiconductor laser that delivers high-power, stable laser output, with selectable wavelength and power based on welding material and process requirements.

SongSheng Optoelectronics Laser Constant Temperature Soldering System with Real-Time Temperature Feedback

The Songsheng Optoelectronics Laser Constant-Temperature Soldering System integrates a real-time temperature feedback system, CCD coaxial positioning system, and semiconductor laser. Featuring an innovative PID online temperature regulation feedback system, it effectively maintains constant-temperature soldering with real-time high-precision temperature control of the soldering target, ensuring superior soldering yield and precision. This system is particularly suited for temperature-sensitive high-precision soldering applications including micro speakers/motors, electronic microphones, connectors, and mobile phone circuit battery boards, among others. 

Application advantages 

In terms of electronic device miniaturization: As electronic devices continue to evolve toward smaller sizes and higher performance, the dimensions of chip capacitors are becoming increasingly compact with narrower spacing. High-power rectangular spot laser welding achieves high-precision, high-density soldering that meets the requirements for micro-component assembly, thereby enhancing the integration level of electronic devices. 

Regarding production efficiency improvement: The multi-point simultaneous welding capability significantly increases soldering speed, enabling high-volume chip capacitor soldering in shortened timeframes. For electronics manufacturers engaged in mass production, this effectively reduces production costs while boosting operational efficiency. 

Concerning product quality assurance: Precise temperature control combined with non-contact welding methodology minimizes soldering defects, improving joint quality and reliability. This ensures consistent performance and stability of electronic equipment while reducing product failure rates and maintenance costs.