Key Techniques for PCB Laser Welding

Key Techniques for PCB Laser Welding     

Materials and Tools Preparation Guide for Laser Soldering

1. Laser Soldering Equipment

• Laser welding head (ensure proper power control capability)

• Multiple options available on the market

2. Solder Materials Selection

• Recommended: Lead-free solder wire

• Standard diameters: 0.8mm or 1.00mm (select based on component       size)

• Options:

• Regular flux-cored wire

• No-clean flux-cored wire (preferred for minimal residue)

3. Flux Considerations

• Flux serves to:

• Remove/prevent oxidation

• Improve solder wettability

• Various flux core types available

4. Base Materials

• PCB circuit boards

• Electronic components to be soldered

5. Workholding

• Purchase appropriate fixtures for component stabilization

• Essential for precision soldering alignment

The Essential Skill of Soldering in Electronics

  Soldering is one of the most fundamental skills in electronics. These two fields are deeply interconnected. While it's possible to learn about and assemble electronic devices without ever picking up a laser soldering head, mastering this simple skill can unlock a whole new world of possibilities. Soldering should be a core competency in everyone's technical skillset. In our rapidly evolving technological landscape, it's crucial for people everywhere to not only understand the devices they use daily but also to modify, repair, and even create them. Soldering is one of the key skills that empowers this capability.

Precision Board Soldering Techniques
Circuit board soldering requires careful attention:

• Excessive heat can detach copper traces from the substrate

• Recommended laser power: 15-25 watts (never exceed this range)

Step-by-Step Process:

1. Surface Preparation

• Gently polish copper pads with a pencil eraser until shiny

2. Material Selection

• Use only rosin-core 60/40 solder

• Select wire gauge matching your component leads

3. Component Installation

• Insert leads through board from the backside

• Bend leads slightly to secure components

4. Soldering Execution

• Simultaneously contact the tinned soldering tip to both lead       and pad

• After 2-3 seconds, feed solder to form a concave fillet (not       convex blob)

• Ensure proper wetting of both lead and copper

5. Completion

• Quickly retract laser and solder wire

• Allow 3-5 seconds undisturbed cooling time

• The joint should appear smooth and shiny when properly       executed

Technical Notes:

• All parameters (15-25W, 60/40 solder) reflect industry      standards

• "Wetting" refers to proper solder flow      characteristics

• Cooling time may vary based on thermal mass

This disciplined approach ensures reliable connections while protecting delicate PCB substrates. Mastery comes through practice with proper technique.

PCB  Laser  Soldering  Parameter  Configuration

Laser Power:
  Select appropriate laser power based on factors such as the type of welding material, thickness, and the size of the welding point. Generally, higher power results in greater welding depth and strength, but excessive power may cause overheating at the welding site, damaging the circuit board or electronic components. For soldering small electronic components on PCB circuit boards, lower laser power is typically required, ranging from a few watts to several tens of watts.

Pulse Frequency:
  The laser pulse frequency affects the heat input and welding quality. Higher pulse frequencies can make the welding process more stable, reducing defects such as spatter and porosity, but they also increase heat accumulation in the welding zone. In practice, adjustments should be made according to specific conditions, with pulse frequencies typically ranging from several tens to several hundreds of Hertz.

Welding Speed:
  The welding speed determines the duration of laser exposure on the welding site. If the speed is too fast, the weld may be weak; if too slow, the welding area may overheat or even burn the circuit board. Generally, for laser welding on PCB circuit boards, the welding speed can be controlled between several millimeters to several tens of millimeters per second.

Spot Diameter:
  The spot diameter directly affects the size of the welding point and energy distribution. A smaller spot is suitable for welding precision components or tiny solder joints, providing higher energy density but requiring greater positioning accuracy. A larger spot is appropriate for bigger solder joints or situations requiring greater heat input. Typically, the spot diameter can be selected between 0.1mm to 1mm.

Songsheng Optoelectronics Laser Constant-Temperature Soldering System:
  Composed of a real-time temperature feedback system, CCD coaxial positioning system, and semiconductor laser; features an innovative PID online temperature regulation feedback system that effectively controls constant-temperature soldering, with characteristics like real-time high-precision temperature control of the soldering target, ensuring soldering yield and precision. Particularly suitable for temperature-sensitive high-precision soldering applications such as PCB components, micro speakers, motors, connectors, cameras, etc.