Solder paste printing is known to be one of the most difficult processes for quality assurance in electronic manufacturing. The challenge increases as the technology development move toward a mix between large modules and small chip components on large and densely populated printed circuit boards. Having a process for quality assurance of the solder paste print is fast becoming a necessity. This article describes a method to ensure quality secured data from both solder paste printers and inspection machines in electronic assembly manufacturing. This information should be used as feedback to improve the solder paste printing process.
The Solder Paste Printing Process
Solder paste printing is one of the most critical processes in electronic manufacturing. The purpose of the process is to apply the correct amount of paste, at the correct position, with the correct form and being able to do this every time a print is performed. Even though the process can be considered relatively simple, the quality results of the print together with the printed circuit board provide the foundation for the rest of the surface mount process. A good print result is a prerequisite for a good soldering result while a poor print will lead to additional process issues as the product travels through the manufacturing chain.
Facing Challenges with Solder Paste Printing
There are many challenges to consistently solder paste printing. Less-than-professional PCB assembly companies will often introduce errors during this delicate process – especially when rushing to complete large orders with tight deadlines.
In order for the process to be successful, PCB assemblers must respect several principles:
- Create a Perfect Stencil: The accuracy of the process depends on the accuracy of the stencil. A shoddy, imprecise, or poorly printed stencil will never produce reliable results.
- Program the Screen Printer Properly: Solder paste screen printing devices need exact measurements and calibration to perform their work with precision. Expert screen printing programming is a valuable skill in the PCB industry.
- Apply the Right Amount of Solder Paste: Too much solder paste will create an imperfect outline, while a lack of solder paste will prevent the SMDs from sticking.
- Choose the Right Process: There are two main methods to achieving a good print – mesh screen printing and metal screen printing. While the former is the cheapest method, it does not work on small SMDs that require precision attachment.
By paying close attention the solder paste printing process, you can accurately gauge just how capable a PCB assembly company truly is. Think of this process as the tell-tale sign of a professional approach.
