Low Temperature Solders and PCB Manufacturing – The Importance of Accurate Heat Application

PCB manufacturing, as a process, is heavily dependent on soldering to make effective and workable electrical connections between different components of the circuitry. With such heavy reliance on soldering, it is imperative that the right choice be made with regards to this aspect of the PCB production process, in which temperature plays a key role. But before you select the right low temperature solder for the job, it is imperative, first, to understand the importance of accurate heat application in the process and how temperature can affect the reliability of the solder bond as well as the quality of the PCB being manufactured. This article will tell you all about it.

Role of temperature in the soldering process

Heating the alloy to its specified melting point sets off a fusion reaction, which makes the metal more wettable and pliable, thereby allowing for its easy application to a circuit board. Electrical components are then placed on to the circuit substrate which are held in place by the wettable alloy, which slowly cools down to form a strong, reliable and electrically conductive bond between surfaces. Temperature, along with the entire heating cycle, plays a key role in the overall soldering process. How long the soldering components take to heat up, how hot they actually get and how long they can sustain this heated temperature, are highly important for successful soldering. The circuit board material, electrical components and other factors related to the manufacture of the PCB are finalized in accordance with this temperature requirement of the soldering alloy.

Effect of temperature mismatch in soldering

A mismatch between the solder temperature and remaining electrical components of the PCB can cause fatal faults in the overall assembly. Some of the issues are highlighted below:

A solder that requires higher temperatures to melt can cause overheating of the connection area, lifted lands, popcorning issues, board damage, poor quality joints and increased oxidation.

• A solder that requires lesser than expected meting temperatures will lead to longer dwell times, poor heat transfer, decreased productivity, inappropriate flux activation and eventually a poor bond between surfaces.

You can therefore, conclude that temperature is the factor that governs the actual quality of the soldering bond created between two surfaces and prevents the damaging effects of thermal shock from ruining the circuit assembly.

Low temperature solders and their benefits

As discussed above, raising the process temperatures to higher degrees for making the soldering alloy wettable can cause irreparable damage to the overall assembly. This damage can be visible (lifted pads, traces, substrate delamination, bubbling, measling, discoloration, board warping and burning) or invisible (internal substrate fracture and component degradation) and it can cause severe faults in the circuitry of the PCB. Low temperature solders help resolve this issue. These are alloys that are lead-free (hence RoHS compliant), and do not create the problem of thermal stress and shock, thereby protecting the integrity of the assembly and ensuring a reliable, functional and high performing PCB being manufactured. They also help in making the manufacturing process more energy efficient and easy to manage.

Hopefully this article has helped you in getting a glimpse of the PCB manufacturing industry and the role that temperature can play in determining the overall quality of produced output.

About the Author:

Alpha Assembly Solutions, Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting, photovoltaics, semiconductor packaging, automotive and others. Since its founding in 1872, Alpha has been committed to developing and manufacturing the highest quality specialty materials.

Alpha Assembly Solutions Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting.