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Decapsulation

Electronic packaging encompasses a huge array of sizes, designs, styles and materials. Gaining access to the chip inside - a technique known as decapsulation - is necessary for many reasons including electrical testing, counterfeit prevention, bond wire pull testing, assuring radiation hard devices with heavy ion testing, photonic and thermal microscopy for failure analysis or competitive analysis. The various physical, chemical and electrical properties of the constituent parts of each package - along with locality requirements, such as a move to green decapsulation (no acids) - dictate the choice of system and decapsulation methodology required for success. 

Many Reasons for Chip Access

QC and QA checks are also required to check for part integrity and anti-counterfeit requirements. Many methods exist to decapsulate the array of packages - no one size fits all!

No 'One Size fits all!'

Early manual methods (such as eye dropper and hot plate)  were joined by more consistent automated acid etch machinery, which provide a comprehensive means of fully decapsulating plastic-packaged components. However, to maintain functional circuitry after the removal of encapsulant materials it is often necessary to use decapsulation sequences and recipes that stay within temperature limits and do not corrode or oxidize bond wires.

Other factors such as the move to green materials and processes, and city and state ordnances, can limit the use of chemicals such as acids in a particular location. To enable the decapsulation of modern devices, ULTRA TEC offers an unsurpassed portfolio of chemicalmechanical and LASER and Plasma systems for the decapsulation of packaged devices. Total Decapsulation Solutions.                                                                                                               

                         

 

Pre-Cavitation

The initial removal of bulk material from the package is typically known as pre-cavitation.

Depending on the package type, chemical decapsulation may work well for the entire decapsualtion. However, survivability and straighter, better defined etch walls are achievable with mechanical or LASER methods. Both of these methods are extremely accurate and effective ways of removing bulk material -- however each must generally be stopped at a finite distance above the die to maintain electrical integrity.  ULTRA TEC's Blue Mill allows for pre-cavitation down to a few microns of remaining encapsulant -- however it is not possible to uncover the bond wires.

Use of Tunnel Decap can mitigate this and make the bond wires more easily obtainable.  The LASER method CAN uncover bond wires, however the final remaining encapsulant thickness is set by the need to avoid a lensing effect of glass filler particles within the encapsulant - normally 100 to 200 microns remaining.

Pre-cavitation can assist in the selection and ease of Final Decapsulation.

Final Decapsulation

The removal of the last 10's of microns to reveal the die surface is know as Final Decapsulation. Acid etch is regarded as the standard baseline method of achieving this. Acids allow for a fast, repeatable results, especially when following pre-cavitation -- temperatures of chemical decap can often be lowered (and thus sample yields increased) if required to remove only the last microns of encapsulant.

Plasma methods are becoming increasingly regarded as the preferred alternative for final decapsulation, particularly for copper devices, and in physical locations where acids are not permitted.

Further Reading

Overview Document: Decapsulation Tool Selection Guide

TEC NOTE #4:  New Mechanical Decapsulation Techniques for Chip Scale Packages (CSP's)

Tunnel Decapsulation Method for Wire-Bonded Packages

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