The laser-induced breakdown spectroscopy (LIBS) used by me from Keyence AE-300 is a type of atomic emission spectroscopy in which a pulsed laser is directed at a sample to vaporize a small part of it, thereby creating a plasma. The radiation emitted from this plasma is then analyzed to determine the elemental composition of the sample. LIBS has many advantages over other analytical techniques. Since only a tiny amount of the sample is needed for analysis, the damage to the sample is minimal. This technique generally requires no special preparation of the samples. Solids, liquids, and gases can even be analyzed directly. LIBS can detect multiple elements simultaneously in a sample and can be used for a variety of samples including biological, metallic, mineral, and other materials. And it provides true real-time analysis, which saves an enormous amount of time.
Measurements on defective headers from Asus, MSI, and Palit, and an older original from a Founders Edition
The PCI SIG has defined in their specification that the sense pins and power pins must be made of brass and that the contact surfaces must be coated with tin. Here, I am measuring an Asus header as an example, but it could have been similar products from the other cards because their pins also deviate from the specifications. The guidelines, however, are also not complete since the composition of the brass is not described. Is it so hard to define such proportions of copper, zinc, even if around 40% zinc to 60% copper is quite common?
This is precisely what I have tested here, of course, first lasering through the plug tip of the Asus header. But something is not right! From the seventh hole onwards, the material becomes very clear:
Of course, I measured the longitudinal sides again because the tip is not the contact surface. The first 15 depth holes still show the coating of tin and nickel and only transition to copper much more slowly:
Here, I have to go considerably deeper because I want to encounter the core material. After over 20 laser shots, it’s finally time:
We find the required, but thin tin layer (Sn), which covers a layer of nickel, until we reach pure copper. This pure form of copper should not be there!
To compare, I have here a header of an RTX 3090 Ti Founders Edition, which could also be driven with well over 450 watts of power consumption. You can see the big difference! The zinc content averages around 40%, which completely changes the mechanical and also optical properties (much brighter) of the pins. That’s exactly how the PCI SIG has defined it! Brass is not pure copper, period!
Interim Insight
Now, it would be tedious to weigh electrical conductivity against mechanical durability, but the PCI SIG certainly did not make these material specifications without reason. From an electrical standpoint, copper is probably the best solution, but brass, depending on the zinc content, is harder and also has a higher shear strength, tensile strength, and also a higher yield strength. The fact is that pure copper bends, compresses, stretches, and twists much more quickly, which can become extremely dangerous with these connectors.
The headers tested here from the defective cards are thus, most likely even with good intentions, relying on the wrong material! Please remember this fact until we come back to the causal connection in which pin width, twisting, positional tolerance, and clamping surface, unfortunately, stand.
- 1 - Introduction, Important Preface, and the PCI SIG
- 2 - Material Analysis with a Key Finding
- 3 - Damage Level 1: Barely Visible or Minor Damage
- 4 - Damage Level 2: Moderate to Major Damage
- 5 - Pin Width, Twisting, Positional Tolerance, and Clamping Surface
- 6 - Summary, Overview of Most Causes, and Conclusion
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