Cover opening detection: how to operate the specific process of chip opening?

Date：2021-09-24 15:47:00Views：3357

When analyzing the internal chips, wires and components in the chip failure analysis, due to the blocking observation of the packaging colloid, the combination of "laser etching" and "wet etching" is used to open the cover (decap) and remove the glue (compound removal), so as to expose the coated objects in the package for subsequent experimental treatment and observation. Opening the chip is equivalent to performing surgery on the chip. Through opening, we can intuitively observe the internal structure of the chip. After opening, we can judge the current situation and possible causes of the sample in combination with OM analysis. This paper collects and arranges some data related to chip cap opening detection, and hopes that this paper can be of great reference value to all readers.

Meaning of KaifengDecap refers to opening, also known as cover opening and cap opening. It refers to local corrosion of the fully encapsulated IC, so that the IC can be exposed, while maintaining the integrity of the chip function, and keeping die, bond pads, bond wires and even lead - from damage, so as to prepare for the next chip failure analysis experiment, facilitate observation or other tests (such as FIB and Emmi). The function after decap is normal.

Unsealing scopeCommon package: cob, BGA, QFP, QFN, sot, to, dip, BGA, cob, ceramic, metal and other special packages.

Unsealing method: generally chemical, mechanical, laser and plasma decap

Kaifeng Laboratory: decap laboratory can handle almost all IC packaging forms (COB, QFP, dip, sot, etc.) and wiring types (Au Cu Ag).

Analysis of advantages and disadvantages of chip capping

Advantages of chip cover opening detection method: it can quickly confirm whether it is produced by the original factory.

Disadvantages of chip cover opening detection method: destructive test, the IC after opening the cover can no longer be used; The chip without original factory logo cannot be opened for confirmation; Opening the cover requires special machinery, equipment and chemicals, which can only be completed by professional institutions.

Under the action of hot concentrated nitric acid (98%) or concentrated sulfuric acid, the polymer resin is corroded into a low molecular compound easily soluble in acetone. Under the action of ultrasound, the low molecular compound is washed away to expose the surface of the chip.

Unsealing method 1: take a stainless steel plate, lay a thin layer of yellow sand on it (or heat the product directly on the steel plate), heat it on the electric furnace, the sand temperature should reach 100-150 degrees, put the product on the sand, the front of the chip faces upward, and use a straw to absorb a small amount of fuming nitric acid (concentration > 98%). Drop it on the product surface. At this time, the resin surface has a chemical reaction and bubbles appear. Drop it again after the reaction stops. After 5-10 drops, clamp it with tweezers and put it into a beaker containing acetone and CH3COCH3. After cleaning in an ultrasonic machine for 2-5 minutes, take it out and drop it again. Repeat this until the chip is exposed. Finally, clean acetone must be used, CH3COCH3 is repeatedly cleaned to ensure that there is no residue on the chip surface.

Chip unsealing method 2:Boil all products in 98% concentrated sulfuric acid at one time. This method is more suitable for the case of large quantity and only depending on whether the chip is broken. The disadvantage is that the operation is dangerous, so we must master the essentials.

Precautions for chip unsealing:

All operations shall be carried out in the fume hood and acid proof gloves shall be worn.

The more the product is opened, the less acid should be dropped and cleaned frequently to avoid excessive corrosion.

During cleaning, the tweezers shall not touch the gold wire and chip surface to avoid scratching the chip and gold wire.

According to the product or analysis requirements, some conductive adhesive under the chip shall be exposed after opening the cap, Or the second point

In addition, in some cases, the open cap products shall be retested according to the row. At this time, first observe whether the gold wire on the chip is broken and collapsed under an 80x microscope. If not, scrape the black film on the pin with a blade and send it for measurement.

Pay attention to control the opening temperature not too high.

Acids commonly used in analysis:

concentrated sulfuric acid: it refers to 98% concentrated sulfuric acid, which has strong dehydration, water absorption and oxidation. When opening the cap, it is used to cook a large number of products at one time. Here, its dehydration and strong oxidation are used.

Concentrated hydrochloric acid: refers to 37% (V / V) hydrochloric acid with strong volatility and oxidation. It is used to remove the aluminum layer on the chip in the analysis.

Fuming nitric acid: refers to nitric acid with a concentration of 98% (V / V). To open the hat. It has strong volatility and oxidation, and is reddish brown due to the dissolution of NO2.

Aqua regia: refers to the mixture of one volume of concentrated nitric acid and three volumes of concentrated hydrochloric acid. It is used to rot gold ball in analysis because it is highly corrosive and can corrode gold.

The above is the related content of "chip cover opening detection" brought by the core creation detection. Through this article, I hope it can be helpful to you. If you like this article, you might as well continue to pay attention to our website, and we will bring more wonderful content later. If you have any needs related to the inspection and testing of electronic products, please call Chuangxin testing, and we will serve you wholeheartedly.