If you’ve ever worked on a circuit board in which you have had to solder or unsolder a through hole component, you already know that these solder joints require exacting precision. Too much solder and it could get into other connections and cause a short. Too little and you may not have a strong enough joint. Cold solder joints could break, and if you get the connection too hot you may cause some damage to the components or the board.
Now take that description and multiply it by all of the through hole components and their leads on your circuit board. There is a reason why your PCB contract manufacturer is the go-to expert when it comes to this kind of work, and that is because they should have the skills, experience, and industry standards from which to work. Here, we’re going to take a look at the IPC through hole soldering standards, and just how a high-quality CM will apply them to working on your printed circuit board assembly.
What IPC Through Hole Soldering Standards Apply to PCB Manufacturing?
For soldering through hole components onto circuit boards, IPC-A-610G—the Acceptability of Electronic Assemblies, is the applicable standard. This standard covers many aspects of printed circuit board assemblies, including definitions of PCB terminology, installing components on a PCB, and of course, soldering various components onto the board. Contract manufacturers should use this standard as their guide when developing and maintaining their own specific through hole soldering processes and procedures.
Section seven of this standard covers through hole component technology and the requirements for successfully soldering these parts onto a PCB. The main concern for PCB contract manufacturers when building boards is the proper formation of a good solder joint. The IPC-A-610 standard specifies how to achieve a good solder joint with requirements for the proper wetting of the solder, combined with the amount of solder fill necessary for a plated through hole.
From here, the CM should develop their own assembly processes to satisfy these requirements. These processes include:
- Component preparation for assembly.
- Component loading into automated assembly equipment.
- Wave solder.
- Selective solder.
- Manual solder (hand soldering).
- Touch-up soldering.
Each of these processes is specifically designed to meet and exceed the requirements for through hole soldering as specified in the IPC-A-610 standard.
Through Hole Soldering Standards for PCB Rework
Once a printed circuit board has come through the automated soldering processes, there still may need to be manual soldering done to the board. This manual work may be part of the initial manufacturing process, or it may be reworked to correct any assembly problems or make changes to an assembled board. Once again, there is a standard that covers how this work should be done.
IPC-7711C/7721C shows the step-by-step process of modifying or repairing circuit boards. The standard contains illustrated chapters for most every PCB repair imaginable and also covers the equipment required for the repairs. Here are the basics the standard covers for through hole soldering modifications or repairs:
- Identifying, removing, and eventually replacing conformal coating on the PCB to facilitate the rework.
- Unsoldering through hole components for removal using vacuum or wicking.
- Repairing a damaged plated through hole.
- Reinstalling and soldering through hole components.
- Changing or correcting silkscreen associated with modified components.
In addition, the standard covers many other aspects of PCB rework and repair. These include:
- Delamination or blister repair.
- Bow and twist repair.
- Hole repair by either patching it with epoxy, or removal and replacement of metal barrel.
- Base PCB material repair.
- Broken or lifted conductor (traces) repair with sealers, adhesives, foil jumpers, or wires.
Both of these standards cover a lot of detailed information that your local CM should put to use when building your printed circuit board assembly.
Soldering Expertise at Your PCB Contract Manufacturer
Knowing and applying these standards on through hole soldering is the key to success when assembling printed circuit boards. The best CMs will embrace the entire standard rather than just focusing on the specific details needed to build an acceptable PCBA. This way, they will already have the infrastructure in place to ensure the best possible conditions for building a printed circuit board. With proper PCBA handling, lighting, equipment, procedures, and other work environment and personnel considerations, following the requirements of the standard will end up being a natural part of their regular workflow.
At VSE, we have that infrastructure already in place. Our facilities are modern and specifically designed for high-quality PCBA manufacturing, and we have more than 30 years of experience building many different types of boards. We meticulously maintain our soldering equipment, from the smallest soldering iron tips to our large wave solder machines, and use the best solder, fluxes, and other materials to ensure the highest quality on the boards we build. Additionally, we employ certified IPC trainers (CITs), giving us the ability to keep our own staff at their peak efficiency, as well as helping our customers and suppliers to understand our manufacturing processes.
