Cytech Systems’ Lab:Can Solder Balls and Pins Reveal These Quality Issues?

July 26, 2023

What worries purchasing agents the most in the process of IC procurement?

It's not the price, but the product quality. There is a wide variety of IC on the market, and it's sometimes challenging to distinguish between different materials. Is the quality up to standard? Specifically, is it genuine or fake, new or refurbished? Even IC procurement veteran find this to be a brain-burning issue.

Cytech Systems’ Lab: Recently, we discovered a batch of components with quality issues. 

What kind of issues? 

Cytech Systems’ Lab: There are serious quality problems with the solder balls. 

Solder balls? What is that? What kind of problems can exist?

Cytech Systems’ Lab: Let me tell you. 

The significance of solder balls for chip packaging.

Solder balls are tin-based alloy balls with the addition of other elements such as silver, copper, and nickel. The conventional ball diameter ranges from 150μm to 760μm.

With the development of chip packaging forms, chip packaging tends to be smaller in size, and it is also moving towards 2.5D, 3D packaging, and other three-dimensional system-level SIP packaging directions. As a core part and direct material that plays the role of electrical signal connection in chip packaging, solder balls not only provide a better solution for high-end chip manufacturing and packaging, but their quality also determines the quality of chip packaging.

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Like the well-known SoC chips in our smartphones, system-level SIP packaged chips in wireless Bluetooth headphones, memory chips on computer RAM modules, and even the CPUs and GPUs in laptops, internally integrated and high-performance chips are all connected to the circuit board and PCB through solder balls, enabling the transmission of electronic signals and ensuring the normal operation of electronic products.

Recently, Cytech Systems’ Lab received a batch of TMS320DM368ZCED and, through external visual inspection, identified several major issues related to solder balls:

01 Solder ball deformation

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Close-up image as shown above, image source: Cytech Systems’ Lab

02 Adhered small solder balls

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Image source: Cytech Systems’ Lab

Based on this, Cytech Systems’ Lab classified this batch of components as high-risk.

Cytech Systems’ Lab: Aside from the quality issues of the materials themselves, another pitfall to avoid in procurement is refurbishment! Have you encountered it?

Cytech Systems’ Lab: Certainly, we have encountered a batch of components with refurbished pins.

Tell us more.

Unmasking the Refurbishment

Here is a batch of ULN2064B, and Cytech Systems’ Lab found several suspicious points during external visual inspection.

 For example, there are no imprints on the pins caused by the outbound test;

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Image source: Cytech Systems’ Lab

For example, the pin cross-section does not reveal the substrate and shows misalignment;
 

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Image source: Cytech Systems’ Lab

For example, there are pinholes on the pin surface;

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Image source: Cytech Systems’ Lab

For example, the pin surface is smooth and shiny, presenting the appearance of being tinned.

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Image source: Cytech Systems’ Lab

Based on various visual inspection results of the ULN2064B, it can be preliminarily determined that this is a batch of problematic components. Out of caution, Cytech Systems’  Lab wanted to further confirm through X-Ray testing. The results of X-Ray testing showed an internal structure consistent with visual inspection. In the end, Cytech Systems’  Lab concluded that this batch of components had refurbished pins and was unacceptable.

Indeed... quality testing is important and can help avoid many pitfalls.

Cytech Systems’ Lab: Absolutely! So, based on years of experience in quality testing, has Cytech Systems’ Lab summarized key points to avoid "refurbished components"?

Cytech Systems’ Lab: Here you go!

IC Refurbishment Identification Guide

01 Check whether the chip surface has signs of polishing

The surface of polished chips will have fine lines or even micro-traces of previous imprints. Some unscrupulous sellers, to conceal these traces, may apply a thin layer of coating on the chip's surface. However, it might appear somewhat glossy, lacking the original plastic texture.

02 Examine the imprint

Most of today's chips use laser marking or specialized chip printing machines for imprints. The characters are clear, inconspicuous, not blurry, and challenging to erase. Refurbished chips either have characters with edges corroded by cleaning agents, giving a "sawtooth" feel, or blurry, uneven, improperly positioned, easily erasable, or overly conspicuous imprints.

03 Look at the pins

If you encounter bright and "new"-looking tin-plated pins, it must be a refurbished product (For example, the incoming component issue we encountered this time with ULN2064B ).

The pins of genuine IC are mostly "silver feet," with a darker color but uniform finish. The surface should not show oxidation marks or "flux," and for dip and other plug-in pins, there should be no signs of smudging. Even if there are smudges (which only occur during repackaging), they should be neat, in the same direction, and the exposed metal should be clean without oxidation.

04 Check the device's production date and packaging factory label

The markings of genuine products, including the markings on the bottom of the chip, should be consistent, and the production date should corresponds to the aging level of the device. In contrast, the markings of refurbished chips without proper remarking are chaotic, with inconsistent production date.

05 Measure the device's thickness and inspect the device's edges

Many refurbished chips with laser markings (especially power devices) must be deeply polished to remove the original mark. Therefore, the overall thickness of the device will be noticeably smaller than the normal size. Without using calipers for comparative measurements, it's challenging for someone with little experience to distinguish. However, there is a flexible way to expose the fraud: look at the device's front edge.

Since molded plastic devices need to be "demolded" after injection molding, the edges of the device should have a rounded corner (radius). However, because of the small size, this round corner can be easily ground into a right angle during polishing. Therefore, when the front edge of the device has a right angle, it can be basically judged as a polished product.

06 Examine the packaging

In addition, judging authenticity by the seller's packaging is another method. Original packaging typically includes a cardboard box, an anti-static plastic bag, and so on.

In recent years, with years of accumulated experience, Cytech Systems has gradually penetrated into the supply chains of many top-tier clients. In the past two years, it has been recognized as an "A-grade supplier" by OEM clients in various industrial and high-precision manufacturing fields worldwide. It has even achieved outstanding scores of 100 points in specific quality assessments conducted by some clients!

In summary, Cytech Systems’ Lab believes that in the field of electronic component distribution, Cytech Systems, which has always regarded quality as its lifeline, is on the right track. 

 

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