Laser unsealing method

Abstract

The invention discloses a laser unsealing method. The method includes the steps that positions and depths of all elements and a chip in a plastic package device are positioned to obtain size, position and depth information of the elements and the chip in the device; according to the information, a preset unsealing area of the plastic package device is determined for unsealing and positioning; laser ablation is conducted on the plastic package device in a cross filling mode to remove molding materials on the surface of the plastic package device, so that inner lead bonding wires are just exposed out of a chip area, tin-lead welding points are just exposed near a resistor and a capacitor, and inductance is just exposed near an inductor. Acidic liquid is adopted to corrode a molding compound covering the chip till the chip is exposed. The method can well solve the problem that a traditional method can not unseal a plastic mixed integrated circuit easily, and effectively increases the unsealing success rate of the plastic package device.

Description

technical field [0001] The invention relates to the technical field of semiconductor unsealing, in particular to a laser unsealing method based on laser technology. Background technique [0002] Plastic-encapsulated device unsealing technology is mainly used in analysis fields such as destructive physical analysis (DPA) and failure analysis (FA) of electronic components. The purpose of the unsealing technology of plastic-encapsulated devices is to remove the original packaging of plastic-encapsulated devices through physical and chemical methods, and to expose the internal chip on the premise of retaining the original electrical characteristics, not damaging the chip, and not introducing secondary failures, and to conduct subsequent evaluations Analysis test. More and more new processes and technologies are gradually applied in the production and manufacture of plastic-encapsulated semiconductor devices, such as highly integrated multi-chip plastic-encapsulated devices, pla...

AI Technical Summary

Problems solved by technology

[0010] However, since the working mode of the acid unsealing machine is to use high-pressure nitrogen as a power source to push the acid to impact the surface of the sample, the unsealing area after the etching of the plastic-encapsulated device unsealing machine is often larger than the predetermined unsealing area (ie, the diffusivity of acid unsealing), which is not conducive to Precise control of Kaifeng area

At the same time, the unsealing process is uncontrolled. The technicians set the temperature of the acid, the flow rate of the acid and the etching time based on experience. The process state of the sample cannot be observed during the unsealing process. The unsealing process is uncontrolled and cannot be intuitively and effectively Control the corrosion of samples in acid solution

[0011] Due to the above problems, it is inevitable that the copper bonding will be corroded and broken, the chips of GaAs and other microwave devices will be damaged, and the bottom printed board of the multi-chip device will be corroded, which will cause the sample to lose its original electrical characteristics or introduce secondary defects.

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