Nov11
OSP vs. ENIG: Which PCB Surface Finish Provides Stronger BGA Solder Joints?

OSP vs. ENIG: Which PCB Surface Finish Provides Stronger BGA Solder Joints?
Figure: OSP vs. ENIG: Which PCB Surface Finish Provides Stronger BGA Solder Joints?

This article uses experimental data to demonstrate that solder joints on OSP-finished PCBs can have higher strength than those on ENIG-finished PCBs. The results also confirm that the solder joint strength of OSP-finished boards deteriorates with aging. OSP performs better at low and medium shear speeds, but the difference becomes smaller at high shear speeds. This suggests that products using OSP-finished PCBs may become more susceptible to solder joint failures as they age in the field.

Keywords: Solder joint strength, solder strength, component drop-off, solder cracking

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Oct28
A Collection of Articles on Component Detachment and BGA Solder Joint Cracking

Cross-section analysis of a BGA solder joint crack
Figure: BGA solder joint craking: causes, analysis & reliability solutions.

BGA solder joint cracking is one of the most challenging issues I’ve encountered throughout my career in electronics manufacturing. It’s also one of the topics that comes up most often whenever engineers discuss product reliability. Even today, there is still no universal solution that can completely eliminate BGA solder joint failures or the functional issues they cause.

While we may not be able to solve every BGA reliability problem, we can certainly reduce the risk and minimize the impact. That’s why Workingbear has gathered this collection of articles on component detachment and BGA solder joint cracking. I hope these resources will serve as a useful reference not only for myself, but also for anyone facing similar challenges.

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Oct21
Can Increasing Solder Paste Volume Improve BGA Soldering Defects Such as HIP?

Can Increasing Solder Paste Volume Improve BGA Soldering Defects Such as HIP?
X-ray image of a BGA showing more solder on the outer rows than on the inner rows.

Improving BGA solder joint quality is an ongoing goal for SMT engineers, especially when working with fine-pitch BGA components. In general, BGAs with a ball pitch of 0.8 mm or less are considered fine-pitch devices, although the exact definition may vary slightly among manufacturers.

BGA soldering is challenging because all the solder joints are located underneath the component body. After reflow, it is difficult to inspect the solder joints visually or with AOI (Automated Optical Inspection) equipment. In some cases, even X-ray inspection cannot reliably determine whether a BGA has open or false solder joints. Certain X-ray systems with oblique-angle imaging or 5DX technology may be able to detect some BGA soldering defects. However, these systems are expensive, and their cost may make them impractical for routine, in-line inspection in high-volume production.

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Oct14
How to Strengthen BGA Solder Joints Through Design to Prevent Cracking

How to Strengthen BGA Solder Joints Through Design to Prevent Cracking
Figcaption: How to Strengthen BGA Solder Joints Through Design to Prevent Cracking

Recently, several colleagues have asked me the same question: How can we improve BGA design to strengthen solder joints and prevent BGA solder ball cracking?

The question came up after a senior executive made it clear during a product development meeting that someone would have to take responsibility if customers continued to report BGA cracking issues. This kind of reaction is not uncommon in product development, but it raises a more important question: Are we addressing the root cause, or are we simply putting more pressure on the engineering team?

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Sep30
What Is HASL Surface Finish? Advantages and Disadvantages

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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