Introduction
ICs are the heart of electronic products, but against the backdrop of global fluctuations in the semiconductor supply chain, high-quality counterfeit chips and refurbished devices are gradually entering the market. This poses significant quality risks for the manufacturing of high-precision electronic products. In PCBA manufacturing, the use of refurbished or high-quality counterfeit ICs can result in anything from failed product debugging to premature failure during end-user operation-severely damaging brand reputation.
To keep these counterfeit components off the production line, quality control measures within the industry must be continuously upgraded. Chip decapsulation, as a crucial method of destructive physical analysis, serves as a highly effective physical defense against high-quality counterfeit and refurbished chips. Below, we will break down how this inspection technology safeguards PCBA quality at the microscopic level.
Core Principles and Physical Processes of Chip Decapsulation
Decapsulation is also known as chemical decapsulation. Its primary objective is to strip away the epoxy molding compound covering the chip's surface-without damaging the internal wafer or wire bonds-thereby fully exposing the internal microstructure.
In practice, inspection technicians use automated decapsulation machines or high-purity strong acids. The most commonly used agents are fuming nitric acid and concentrated sulfuric acid, with temperatures ranging from 60 to 90 degrees Celsius and concentrations exceeding 90%. Strong acids rapidly oxidize and dissolve the epoxy encapsulant, while the internal silicon wafer, silicon dioxide dielectric layer, and passivation layer exhibit extremely high resistance to these acids. Following a precisely controlled chemical reaction, the sample is cleaned using an ultrasonic cleaner with anhydrous ethanol. Technicians then obtain a chip sample with the wafer exposed and all leads intact, physically preparing it for subsequent microscopic inspection.
Microscopic Inspection of Gold Wire Bonding and Frame Morphology
After chemical decapsulation is complete, technicians examine the sample under a high-magnification metallographic microscope, typically set at a magnification between 100x and 1,000x. The first step in the microscopic inspection focuses on the wire bonding and frame structure. Refurbished chips have often undergone secondary processing. Under the microscope, if peeling, scratches, or traces of secondary wire bonding are observed on the internal frame plating, it strongly suggests that the device is likely a recycled part. In particular, at gold or copper wire bonding points, the bonding balls of a normal chip are full, smooth, and circular, with tight contact to the wafer pads. In contrast, refurbished devices often exhibit deformed bonding balls, damaged pads, or even residual intermetallic compound debris from previous soldering. These subtle physical deformations and residues are clearly visible under a 1,000x magnifying glass.
Comparative Analysis of Wafer Silkscreen and Layout Features
The most difficult aspect of counterfeit chips to guard against is the forgery of external silkscreen markings; laser marking machines can easily replicate the model numbers and batch numbers on the package. However, de-caps inspection allows for direct observation of the chip's "DNA": the wafer layout. By placing the de-capsed wafer under a scanning electron microscope or high-magnification microscope, technicians can clearly see the microscopic circuit lines and silkscreen markings (i.e., the die mark) on the wafer's surface. During manufacturing, legitimate wafer fabs etch the design company's logo, wafer code, layout version number, and copyright year onto the wafer's edge or specific areas. The line widths of these microscopic screen-printed marks are typically sub-micrometer in size. Since high-quality counterfeit chips often use low-end wafers for functional substitution, their wafer screen printing, photolithographic patterns, and circuit layout will inevitably differ significantly from those of genuine, original chips. By performing a pixel-level comparison of the test sample's Die Mark against the original manufacturer's official database or standard reference samples, the authenticity of the chip can be instantly determined.
In-Depth Investigation of Failures Caused by Microcracks and ESD Damage
De-caps testing is not only used for authenticity verification but is also an indispensable method in PCBA failure analysis. During the debugging phase of PCBA manufacturing, if functional defects are encountered and IC damage is suspected, de-caps testing can be performed to inspect for physical damage under a microscope. Refurbished chips that have been in service for a long time often accumulate microscopic cracks internally. These cracks are mostly distributed along the wafer edges or at the corners of the package; under temperature fluctuations and physical vibrations, they can propagate inward toward the wafer core, causing metal interconnects to break. Additionally, breakdown points caused by electrostatic discharge (ESD) appear under a microscope as localized silicon melting or burnout of the passivation layer. This microscopic physical pathology analysis helps process engineers accurately determine whether a failure is due to aging of raw materials or a flaw in ESD protection during the manufacturing process.
Mitigating device risks requires scientific data and rigorous processes. To ensure the reliability of every solder joint and the authenticity of every component, we continuously upgrade our testing technologies and have built a robust quality defense system ranging from IQC incoming inspection to in-depth destructive analysis.
Quick facts about NeoDen
- Established in 2010 with 200+ employees & 27,000+ Sq.m. factory of independent property rights, to ensure the standard management and achieve the most economic effects as well as saving the cost.
- Owned the own machining center, skilled assembler, tester and QC engineers, to ensure the strong abilities for NeoDen machines manufacturing, quality and delivery.
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- The unique one among all of the Chinese manufacturers who registered and approved CE by TUV NORD.
- NeoDen supplies life-long technical support and service for all of the NeoDen machines, moreover, regular software updates based on the using experiences and actual daily request from the endusers.