Unlocking Efficiency with IC Decapsulation in Printed Circuit Boards
Admin, January 18,2024
IC Decapsulation in Printed Circuit Boards
Printed Circuit Board Repair
Regular electronic gadgets depend on printed circuit boards for their function. Any fault in the PCB leads to its failure, so you have to test the board to detect its faults. IC decapsulation is a way to analyze the circuit board. It is a process of exposing the silicon chip by removing the packaging material. The outer material is a microchip that has a silicon chip inside which processes the entire data. The firmware also resides in the microchip like in devices having micro-controllers.
The silicon chip contains several IC secrets that an expert has to uncover to detect the fault. You have to explore the die and take pictures of every layer to find the failure. Microprocessors have routing layers in metal and you can capture them through an optical microscope or tools like SEM or TEM. The de-lidding of IC helps debug the hardware, check if the parts are authentic, and reverse engineering as it helps reach the main circuitry.
Why Should You Decapsulate a Chip?
You have to decapsulate the chip for certain reasons, such as:
- To analyze the failure
- Reestablishing the lock bits
- Micriprobing
- Detecting the counterfeit chips
- To read any hidden ROM
Decapping by Hackers
Many small companies and hackers decapsulate integrated circuits to analyze counterfeits and their parts or to transfer the silicon die’s pictures. In such a case, you can go for a DIY process. Different techniques and materials are there for IC decapsulation.
Some hackers do it just for fun like to override the firmware of a hardware that needs a more commercial method. Moreover, which method you should use depends on your requirements like if you want to keep the chip or want to destroy it. Let’s explore both destructive and non-destructive ways in this regard.
Destructive Technique Of IC Decapsulation
You can do it in different ways, such as:
- Completely burning the encapsulation with a blowtorch.
- Immersing the whole chip in an acid-based chemical to remove the wires, capping material, die, and bonds.
So in this case, you cannot use the chip afterward.
Non-Destructive Technique of Decapsulation
You can do it in different ways, such as:
- Recapping through wet chemicals like using acid and rubber gaskets.
- Manually apply acid on the required IC, removing the residue, and capping.
- Etching with plasma and tools that drain away the residue or encapsulation. However, the tools are expensive, in this case.
So, the chip is still usable after IC decapsulation as you don’t destroy the external parts, die, and wires. The second method is economical in this case.
Micro-Abrasion Decapsulation
In micro-abrasion, you have to take the 2D x-ray to find the die details including its location, wire bonds, and much more. Experts use Cu tape around the packaging material to keep the board safe from abrasives, such as sodium bicarbonate. You have to set the tool nozzle at 40 psi, and the abrasive is first sprayed on the Cu tape before blasting it on the removable cap. Then, you can remove the over-mold by moving the nozzle on all sides to remove the material in bulk. Better keep the pressure up to 30 psi to protect the components below. Finally, you can apply another microabrasion to clean the residue on the PCB. Then remove the Cu tape and check the board for any damage after abrasion.
Laser Ablation for IC Decapsulation
Laser ablation is a non-chemical technique to remove an IC packaging. It is an isotropic process, so it sends the encapsulating residue under the wires, needing further cleaning with anisotropic. There is also a chance of die damage due to a high temperature. To deal with such issues, first, you have to apply laser ablation to decapsulate most of the package.
As you recap near the wires and die you can apply the ICP or inductive coupled plasma. The ICP helps to remove the material without affecting the package function. Though easy, it’s a time-consuming method, so experts use laser ablation before applying plasma. However, the use of RIE at a high temperature can damage the IC.
Mechanical Decapping
Mechanical decapsulation is suitable for ceramic packaging. You can chisel off the cap with a hammer and a razor. It is a non-destructive method of IC decapsulation.
Safety Measures to Take During Decapsulation Of Integrated Circuits
Since IC decapsulation involves chemicals, you have to take certain safety measures to protect yourself. Let’s explore these measures in detail.
- Make sure to perform the task outside and windows should not be open. A fume hood would serve well in this case.
- Use goggles to prevent splashes of harmful chemicals. If the glasses get fogged, remove them away from the work area.
- A respiratory mask is also essential to filter the fumes. It would be better if you wear a face mask, covering the entire face. In other words, you will have to protect your face from acid that splashes during IC decapping. Gloves are also essential, but avoid nitrite gloves while decapsulation with nitric acid. You should use neoprene gloves for nitric. Whereas some delicate tasks need vinyl gloves.
- Try not to expose your skin and work with shoes on. Besides, avoid shorts and wear long sleeves. A lab coat is ideal in this case, as it’s easy to drag acid-affected coat without harming the face.
- You must know the properties of two chemicals before mixing them. Don’t mix different chemicals, besides, only a small quantity of essential chemicals should be in the lab or work room.
- Anything can happen, so the nearby safety materials must have sodium bicarbonate to minimize the effect of an acid. But, remember that bicarbonate emits heat.
- Water should be at hand to rinse off the chemicals during splashing. Make sure you have a surplus amount of water.
- Immediately seek medical help if the chemical hurts your skin or eyes during IC decapsulation.
A Step By Step Guide To Chemical Etching Technique
Chemical or acid etching is suitable for plastic packaging. Here, we will discuss a complete process in this regard.
1: First, you will have to inspect the die through an X-ray to see its relativity with an IC. You can also read the data sheet provided by the manufacturer to see the distance from the package top to the die. Take a marker and outline the die on the top of the integrated circuit. Also, check the die’s depth by marking its side.
2: Take the rotary and drill a small hole into the circuit or IC. You can adjust the drill speed according to your comfort. Drill around the marked outline, including the depth of the die. Be careful while doing so to protect the bonds and die from any damage.
3: Preheat the plate at 100°C in the fume hood. Keep a few things at hand, including tweezers, a spray bottle, and a waste breaker. Moreover, the fume hood should have many disposable pipettes.
4: In this step, you must keep safety gadgets at hand, including a lab coat, gloves, goggles, etc. Also, adopt necessary precautions and put 10 to 15ml of nitric acid and sulfuric acid into the required vias. Make sure to pour fuming acids, and perform this task below a fume hood.
5: Pour some nitric acid into the drilled hole while the plate reaches 100°C. Let the acid etch the packaging and continue till the chemical reaction gets slow. Hold the integrated circuit with tweezers by getting it on the waste beaker to remove debris with acetone.
Make sure that acetone is away from the hot plate as it catches fire very fast. After exposing the die, use sulfuric acid to clear the plastic lid near the wire bonds. When the acid reaction gets slow, stop the process, as the acid can harm the inner circuitry because it stops removing the cap.
Frequently Asked Questions
What Is IC Decapsulation In a Printed Circuit Board?
The decapsulation of an integrated circuit means removing the lid or cap from the IC packaging.
How Many Techniques Are There For IC Decapsulation?
Experts decapsulate the IC with chemicals, heat, or through mechanical tools. However, chemical decapping is common.
What is An Integrated Circuit?
An integrated circuit or IC is a combination of components on a PCB. These components are arranged through soldering as one package.
What Is The Reason Behind Decapsulation?
The reason behind IC decapping is to test the failure, reestablish the lock bits, as well as microprobe, detect the counterfeit chips, and read any hidden ROM.
Final Thoughts
There are different methods of IC decapsulation of which chemical decapping seems ideal as all wire bonds are safe, and the device remains functional. However, it’s a standalone technique. You can perform it on both flex and rigid circuit boards.
The decapsulating of the IC helps debug the hardware, check if the parts are authentic, and reverse engineering, as it helps reach the main circuitry.
which method you should use, depends on your requirements like if you want to keep the chip, or want to destroy it.
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