IC Decapsulation in Printed Circuit Boards

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:

1. Completely burning the encapsulation with a blowtorch.
2. 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:

1. Recapping through wet chemicals like using acid and rubber gaskets.
2. Manually apply acid on the required IC, removing the residue, and capping.
3. 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.