TWI772140B - A method of separating a special large-scale ic package for failure analysis from a printed circuit board - Google Patents

Abstract

The present invention discloses a method of separating a special large-scale IC package for failure analysis from a printed circuit board, which is characterized in that a constant temperature oven and a heating hotplate are used, and the special large-scale IC package mounted by soldering on the surface of the printed circuit board can be easily separated from the surface of the print circuit board by a stripping tool to facilitate subsequent failure analysis of the special large packaged IC.

Description

A method of removing a special large package IC for failure analysis from a printed circuit board

The present invention relates to a method for removing a special large package IC for failure analysis from a printed circuit board.

The ICs after flip chip packaging are all connected to the PCB board by solder balls. The number of solder balls ranges from hundreds to even thousands, and there are more small ICs and small solder balls inside each packaged IC. complex structure. In order to analyze the demand, it is quite difficult to completely remove the packaged IC that has been fixed on the PCB board, and the packaged IC function can still operate normally, because the inherent method is to put the PCB board on the heating platform first. , heated to a temperature slightly lower than the melting point of the solder ball, and finally use a flat-blade screwdriver or similar tool to separate the packaged IC from the PCB board, but because the PCB board is a material with poor thermal conductivity, the temperature difference on the board is very high Large, some places have reached the set temperature, and some are still far below the set temperature. During the separation process of the packaged IC and the PCB board, the IC will be damaged, and because the temperature of some parts of the IC is already higher than the melting point of the solder balls, the packaged IC itself solder balls Serious deformation, or welding with the adjacent solder balls, causing trouble or inability to analyze after the event.

In view of this, this invention proposes an innovative method for removing the special large package IC for failure analysis from the printed circuit board, which can improve the success rate of removing the special large package IC for failure analysis, so as to facilitate the subsequent failure analysis. conduct.

An object of the present invention is to disclose a method for removing a special large package IC for failure analysis from a printed circuit board, the steps of which include: providing a printed circuit board, the printed circuit board has opposite first and second surfaces, And the first surface includes a special large package IC, the special large package IC is fixed on the first surface of the printed circuit board with a solder; cut the printed circuit board to obtain a cutting sample, the The cut sample includes a cut printed circuit board and a special large package IC fixed on the cut printed circuit board, and the vertical projected area of the cut printed circuit board is slightly larger than the special large The vertical projected area of the packaged IC; a metal foil is provided, and the cut sample is covered with the metal foil to form a coated sample, and the coated sample is placed in a constant temperature oven at a first temperature T1 Heating evenly in the environment for 1-2 hours; removing the uniformly heated coated sample from the constant temperature oven, removing the metal foil, and placing the cut sample on a heating plate with a second temperature T2 on, making the cut printed circuit board of the cut sample continue to be heated by the heating plate, wherein the second temperature T2 is greater than the first temperature T1, and 50ºC≦(T2-T1)≦70ºC; and a Stripping tool, inserting the stripping tool between the special large package IC of the cut sample and the cut printed circuit board, and applying an external force to make the special large package IC and the cut printed circuit The plates are completely separated.

As described above, in the method of removing the special large package IC for failure analysis from the printed circuit board, the step of cutting the printed circuit board to obtain a cut sample can be performed using a mechanical cutting machine or a laser cutting machine.

The method of removing the special large package IC for failure analysis from the printed circuit board as described above, the mechanical cutting machine is a chainsaw.

The method of removing the special large package IC for failure analysis from the printed circuit board as described above, the metal foil is aluminum foil or tin foil.

The method for removing the special large package IC for failure analysis from the printed circuit board as described above, wherein the first temperature T1 is between 200°C and 220°C.

The method for removing the special large package IC for failure analysis from the printed circuit board as described above, wherein the stripping tool is a metal sheet, a blade or a flat-blade screwdriver.

The embodiments of the present invention will be described in detail below. It should be noted, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific forms. The specific embodiments discussed herein are illustrative only and are not intended to limit the scope of the invention.

Example

This embodiment is described in detail below with reference to FIGS. 1A to 1H .

First, referring to FIG. 1A , a printed circuit board 100 as shown in the top view of FIG. 1A is provided. The printed circuit board 100 has opposite first and second surfaces 100A and 100B, and the first surface 100A includes a The special large package IC 110 is fixed on the first surface of the printed circuit board 100 with solder 150 .

Next, referring to FIG. 1B , the printed circuit board 100 is cut to obtain a cut sample 200 as shown in FIGS. 1C-1 and 1C-2 . 1C-2 is a cross-sectional view according to the section line I-I' of the top view of FIG. 1C-1. As shown in FIGS. 1C-1 and 1C-2 , the cut sample 200 includes a cut printed circuit board 100 ′ and a first printed circuit board 100 ′ fixed to the cut printed circuit board 100 ′ by solder 150 The special large package IC 110 on the surface 100A, and the vertical projected area of the cut printed circuit board 100 ′ is slightly larger than the vertical projected area of the special large package IC 110 . The above step of cutting the printed circuit board 100 can be accomplished by, for example, but not limited to, a mechanical cutting machine or a laser cutting machine, wherein the mechanical cutting machine is, for example, but not limited to, a chainsaw.

Next, referring to FIG. 1D , a metal foil 300 is provided, and the cut sample 200 is covered with the metal foil 300 to form a covered sample 350 . Then, as shown in FIG. 1E, the coated sample 350 is placed in a constant temperature oven 400, and heated evenly for 1-2 hours under the environment of the first temperature T1. In this embodiment, the metal foil 300 may be, for example, but not limited to, aluminum foil or tin foil. The first temperature T1 set by the constant temperature oven 400 is, for example, but not limited to, between 200ºC and 220ºC.

Then, referring to FIG. 1F, the uniformly heated coated sample 350 is removed from the constant temperature oven 400, the metal foil 300 is removed, and then the cut sample 200 is placed in an oven with a second temperature T2 On the heating plate 500, the cut printed circuit board 110' of the cutting sample 200 is continuously heated by the heating plate 500 through the second surface 110B, wherein the second temperature T2 is greater than the first temperature T1, and 50ºC≦(T2-T1)≦70ºC.

Finally, referring to FIG. 1G , a stripping tool 600 is provided, and the stripping tool 600 is inserted between the special large package IC 110 of the cut sample 200 and the cut printed circuit board 100 ′, and an external force is applied , so that the special large package IC 110 and the cut printed circuit board 100 ′ are completely separated as shown in FIG. 1H , so as to facilitate the subsequent failure analysis of the special large package IC 110 . The peeling tool 600 used in this embodiment can be, for example, but not limited to, a metal sheet, a blade or a flat-blade screwdriver

To sum up, the method of dismounting the special large package IC for failure analysis from the printed circuit board disclosed in the present invention is to uniformly heat the cut sample including the package IC, so that it is fixed on the printed circuit board by soldering. The special large-scale packaged IC on the surface of the circuit board can be easily removed to avoid damage to the IC or serious deformation of the solder balls of the packaged IC itself, so it is conducive to the subsequent failure analysis of the special large-scale packaged IC.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be determined by the scope of the appended patent application.

100: Printed Circuit Board 100A: first surface 100B: Second Surface 100': cut printed circuit board 110: Special large package IC 150: Solder 200: Cut the sample 300: metal foil 350: Coated sample 400: constant temperature oven 500: heating plate 600: Stripping Tool I-I': Hatch line

FIGS. 1A to 1H are schematic top views and cross-sectional views of a process of a method for removing a special large package IC for failure analysis from a printed circuit board according to an embodiment of the present invention.

100': cut printed circuit board

110: Special large package IC

150: Solder

200: Cut the sample

500: heating plate

600: Stripping Tool

Claims (6)

A method for removing a special large package IC for failure analysis from a printed circuit board, the steps comprising: providing a printed circuit board, the printed circuit board has opposite first and second surfaces, and the first surface includes A special large-scale package IC, the special large-scale package IC is fixed on the first surface of the printed circuit board with a solder; cutting the printed circuit board to obtain a cutting sample, the cutting sample includes a cutting The cut printed circuit board and the special large package IC fixed on the cut printed circuit board, and the vertical projected area of the cut printed circuit board is slightly larger than the vertical projected area of the special large package IC; A metal foil is provided, and the cut sample is covered with the metal foil to form a coated sample, and the coated sample is placed in a constant temperature oven, and heated evenly for 1-2 times under the environment of the first temperature T1 hour; remove the coated sample after uniform heating from the constant temperature oven, remove the metal foil, and place the cut sample on a heating plate with a second temperature T2 to make the cut sample The cut printed circuit board is continuously heated by the heating plate, wherein the second temperature T2 is greater than the first temperature T1, and 50°C≦(T2-T1)≦70°C; and a peeling tool is provided, and the The peeling tool is inserted between the special large package IC of the cut sample and the cut printed circuit board, and applies an external force to completely separate the special large package IC from the cut printed circuit board. According to the method for removing a special large package IC for failure analysis from a printed circuit board as described in claim 1, the step of cutting the printed circuit board to obtain a cut sample can be accomplished by using a mechanical cutting machine or a laser cutting machine . The method for removing a special large package IC for failure analysis from a printed circuit board as described in claim 2, the mechanical cutting machine being a chainsaw. The method for removing a special large package IC for failure analysis from a printed circuit board as described in claim 1, the metal foil is aluminum foil or tin foil. The method for removing a special large package IC for failure analysis from a printed circuit board according to claim 1, wherein the first temperature T1 is between 200°C and 220°C. The method for removing a special large package IC for failure analysis from a printed circuit board as described in claim 1, wherein the stripping tool is a metal sheet, a blade or a flat-blade screwdriver.

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