Sep30
What Is HASL Surface Finish? Advantages and Disadvantages

post on September 30, 2026
What Is HASL Surface Finish? Advantages and Disadvantages
Figcaption: What Is HASL Surface Finish? Advantages and Disadvantages

HASL stands for Hot Air Solder Leveling and is one of the most common PCB surface finishes. It is commonly referred to simply as HASL or a solder coating. During the HASL process, the finished PCB is immersed in molten solder so that the exposed copper surfaces are coated with solder. Hot-air knives then remove excess solder and level the coating to provide a solderable surface.

The solder coating protects the exposed copper from oxidation and provides a solderable surface for component assembly. HASL equipment can generally be divided into two types: vertical and horizontal systems, each with its own advantages and disadvantages. HASL is available in both leaded and lead-free versions, but this article focuses primarily on lead-free HASL.

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PCB/FPC/PTF, Soldering, Uncategorized     WorkingBear    Views (15)     comment (0)
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Sep16
Component Drop-Off on PCBs: How to Analyze, Troubleshoot, and Identify the Root Cause

post on September 16, 2026
Component Drop-Off on PCBs: How to Analyze, Troubleshoot, and Identify the Root Cause
Figcaption: Component Drop-Off on PCBs: How to Analyze, Troubleshoot, and Identify the Root Cause

Components falling off a PCB can be a nightmare for many process and quality engineers. Workingbear has previously shared several cases involving components falling off PCBs. However, the root cause can be different in every case. Many engineers, especially those who are new to this type of failure, may not know where to start when they encounter a component detachment problem. So, I would like to share the approach and analysis steps I typically use as a practical reference.

(Of course, I welcome other professionals to share their own experience and insights. Different opinions and discussions are how we learn and improve. Workingbear does not claim that this is the best or only way to analyze the problem. It is simply a summary of my own practical experience.)

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Design, EDX/EDS/SEM/IMC/FTIR, PCB/FPC/PTF, Process, Quality, Reliability, Soldering     WorkingBear    Views (304)     comment (0)
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Sep09
How to Read a BGA Red Dye Penetration Test Report: What the Results Really Mean and How to Interpret Them

post on September 9, 2026
How to Read a BGA Red Dye Penetration Test Report: What the Results Really Mean and How to Interpret Them
Figure 1: How to interpret the deeper meaning of a laboratory BGA red dye penetration test report

If I showed you the microscope image above (Figure 1), taken right after a Red Dye Penetration Test, could you tell Workingbear what happened to the solder joints on this BGA? Actually, Figure 1 has already used red boxes to point out where the solder balls cracked. But beyond that, how much of the story behind the failure can you figure out?

Over the past few days, Workingbear has been analyzing quite a few BGA Red Dye Penetration Test results. It almost feels like everyone agreed to send them in at the same time. Suddenly, we have multiple different products and PCBAs, all with BGA-related issues.

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Quality, Reliability, Soldering     WorkingBear    Views (336)     comment (0)
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Sep02
BGA Red Dye Penetration Test: Acceptance Criteria for Cracks and Voids

post on September 2, 2026
Acceptance Criteria for Red Dye Penetration Test Analysis
Figure: BGA Red Dye Penetration Test: Acceptance Criteria for Cracks and Voids

A reader asked Workingbear, “After performing a Red Dye Penetration / Red & Pry Test on a BGA, how should we determine the acceptance and rejection criteria?”

At first, this question really stumped Workingbear. The Red Dye Penetration Test is a destructive test, and its primary purpose is generally to check whether BGA solder balls have cracks or other soldering defects. Therefore, there is usually no formal acceptance criterion specifically for this test. The test can mainly be used to determine whether a solder ball has cracked.

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Quality, Reliability, Soldering     WorkingBear    Views (265)     comment (0)
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Aug25
[Case Study] BGA Solder Ball Cracking: Strain Gauge Analysis and Design Improvement

post on August 25, 2026
BGA soldering crack analysis: using Cross-Section
Figcaption：BGA soldering crack analysis: Cross-Section shows crack locate at IMC location

During new product development, electronics companies may encounter BGA solder ball cracking after a drop test in which the bare unit is dropped from a specified height. When this happens, the R&D team should take a systematic approach and perform a stress-strain analysis rather than immediately assuming that the BGA cracking is caused by the SMT process.

Based on Workingbear’s experience, BGA solder ball cracking is often difficult to resolve through SMT process controls or simply by increasing the amount of solder. In many cases, the root cause is related to the mechanical design of the product. Addressing the problem at the design stage can significantly reduce manufacturing costs and engineering effort later in the product life cycle.

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Case study, Design, Quality, Reliability     WorkingBear    Views (411)     comment (0)
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