mobile | classic
Dataweek Electronics & Communications Technology Magazine

Follow us on:
Follow us on Facebook Share via Twitter Share via LinkedIn


Electronics Buyers' Guide

Electronics Manufacturing & Production Handbook 2017


Laser soldering for ultrafine parts or high density mounting
11 October 2017, This Week's Editor's Pick, Manufacturing / Production Technology, Hardware & Services

Laser soldering is currently gaining attention as a new soldering method. However, as this is a new industrial technique compared to iron tip soldering, the heating principles differ, and it cannot simply replace iron soldering.

Without understanding and properly utilising the technical characteristics of both laser and iron soldering, soldering stability and quality are unattainable. This article will explain the principles of laser soldering, as well as guidelines for its use.

The mechanism of laser heating

Laser heating differs from iron heating in that it is fundamentally a surface heating process, rather than a process of heat transfer. There are three basic steps in a soldering heating process: the first to preheat the soldering points, the second to apply heat in order to feed the solder, and the third to post-heat to set the shape. Both iron and laser soldering follow these steps, but the heat conversion process of the two methods is different. Understanding these differences is necessary in order to select the most appropriate method for required soldering outcomes.

The iron soldering heating process, as illustrated in Figure 1, comprises the following steps:

1. Heating the iron tip to the set temperature.

2. Applying the tip to the soldering point to achieve fusion temperature around the area.

3. Feeding solder wire.

On the other hand, laser soldering (Figure 2) works as follows:

1. Applying laser shot to soldering point.

2. A land point developing heat.

3. The pad surface heats up to fusion temperature.

4. Feeding the solder.

In the iron soldering method, its heat is transferred through iron tips (heat transfer), while laser soldering produces heat on the applied points (surface heating).

Based on these methods, iron soldering does not heat over the set temperature in most cases, however if the iron continues to be applied, the surrounding area will heat up. In contrast, laser soldering heats the applicable area locally and the absorbed energy instantaneously raises its heat level. Thus, carelessness during laser soldering will quickly lead to overheating. As a result, to carry out laser soldering correctly, expertise and experience in both soldering and laser technology are required.

Consequences of temperature being too high or too low

As the composition of solder changes based on heating conditions, neither sufficient strength nor reliability can be realised without soldering at the proper temperature. For example, the internal composition of solder is mostly unchanged when soldered at the proper temperature, but when it is overheated, strength and reliability are diminished as a result of composition changes.

In addition, the liquidity of flux changes based on temperature. For instance, when properly heated, the flux first flows into the soldered points and through-holes, removing dirt and oxides in the area and improving the soldering compatibility. In contrast, when overheated, solder moves into through-holes and stops flux flow. Furthermore, overheating easily damages circuit boards, leaving cracks on the inside.

Nowadays there is an interest in moving from iron soldering to laser soldering, simply because of its technological benefits as well as little required maintenance. However, without understanding the laser’s distinct characteristics for soldering applications, its potential advantages can be wasted.

Advantages of laser soldering

Laser soldering can be a very useful technology for operations which are difficult or impossible with iron tip soldering, so long as the heating conditions are carefully set in advance.

The main advantage of laser soldering is its non-contact action – it has no contact with the circuit board or electronic parts, so soldering is accomplished without any physical damage. Efficient and pinpoint heating is another advantage which is applicable for narrow and tight places. Furthermore, it needs less consumable materials such as iron tips, which significantly reduces daily maintenance workload.

On the other hand, highly reflective materials make it difficult for a laser to apply heat to the target, and in such a case the heat transfer mechanism of iron soldering is preferable.

Technology advancement

After successful commercialisation, laser soldering equipment has been adopted by electronics manufacturers of smartphones, medical devices, and many others. Throughout the uptake of the technology, the soldering laboratory at Japan Unix has been collecting data on safety, reliability and fusion strength through actual inspections and evaluations, and the value of adopting laser soldering continues to be demonstrated.

For more information contact Igmar Grewar, Quamba Technologies, +27 (0)83 417 4294,,

  Share on Facebook Share via Twitter Share via LinkedIn    

Further reading:

  • UCT fund helps engineering student beat the odds
    18 April 2018, This Week's Editor's Pick, News
    Last year the fund assisted 76 engineering students with their individual needs, at a cost of R383 000.
  • Open SMT assembly standard enjoying strong uptake
    18 April 2018, Manufacturing / Production Technology, Hardware & Services, News
    The standard can be adopted by any equipment manufacturer without any licence fee, and already counts nearly 30 vendors among its members.
  • The rise of edge computing
    18 April 2018, TRX Electronics, This Week's Editor's Pick, Computer/Embedded Technology
    Edge computing in relation to IoT is opening up new opportunities for embedded designers.
  • Embedded deep learning framework for FPGAs
    18 April 2018, ASIC Design Services, This Week's Editor's Pick, Programmable Logic
    ASIC Design Services has developed a scalable and flexible embedded deep learning solution that allows for the implementation of a wide range of convolutional neural networks on FPGAs.
  • Smart grid management system developed by Cape Town company
    18 April 2018, Arrow Altech Distribution (AAD), This Week's Editor's Pick, News
    Based in Cape Town, CT Lab is a technology company specialising in the monitoring and management of electrical networks in the energy distribution, facility and industrial sectors. The company offers ...
  • R&D tax incentive applications streamlined
    21 March 2018, This Week's Editor's Pick, News
    The South African government has reduced the red tape required for companies to apply for a research and development (R&D) incentive, by reducing the turnaround time to 90 days.
  • Local manufacturers look forward to a brighter future
    21 March 2018, Omnigo, SMTech, Grand Tellumat Manufacturing, This Week's Editor's Pick, News, Manufacturing / Production Technology, Hardware & Services
    Dataweek interviewed three South African electronics contract manufacturers to find out what they’ve been up to lately, and what their outlook is.
  • Lessons learned from an ECM and the customer that sued them
    21 March 2018, MyKay Tronics, This Week's Editor's Pick, Manufacturing / Production Technology, Hardware & Services
    The plaintiff created a new technology that consisted of a sensor and a receiver, but lacked the ability to produce it. Enter the contract manufacturer, soon to be the defendant.
  • Industry urged to submit waste management plans
    21 February 2018, This Week's Editor's Pick, News
    Bubele Nyiba, CEO of the ROSE Foundation, believes that although formalised plans will benefit the environment, a pivotal question is who will ultimately bear the cost for their implementation.
  • Power designers are being challenged by spec changes
    21 February 2018, Supreme Electro Magnetics, This Week's Editor's Pick, Power Electronics / Power Management
    A survey conducted by Vicor has revealed that mitigating the impact of inevitable changes to power system requirements is essential to ensure projects are on time and within budget.
  • Series and parallel battery configurations
    21 February 2018, Uniross Batteries, This Week's Editor's Pick, Power Electronics / Power Management
    Batteries achieve the desired operating voltage by connecting several cells in series; each cell adds its voltage potential to arrive at the total terminal voltage. Parallel connection attains higher ...
  • Directory of suppliers
    EMP 2018 Electronics Manufacturing & Production Handbook, Manufacturing / Production Technology, Hardware & Services

Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronic Buyers Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Terms & conditions of use, including privacy policy
PAIA Manual


    Classic | Mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.