TW202308476A - 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 special large packaged ICs for failure analysis from printed circuit boards

The present invention relates to a method of unloading a special large packaged IC for failure analysis from a printed circuit board.

The flip-chip packaged ICs are connected to the PCB board with 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 function of the packaged IC can still operate normally, because the inherent method is mainly 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 flathead 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 large Large, some places have reached the set temperature, and some are still far below the set temperature. In the process of separating the packaged IC from 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 ball, the solder ball of the packaged IC itself Seriously deformed, or welded together with the adjacent solder balls, causing confusion or failure to analyze afterwards.

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

One object of the present invention is to disclose a method for unloading 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 a first and a second surface opposite, And the first surface includes a special large-scale package IC, and the special large-scale package IC is fixed on the first surface of the printed circuit board by using a solder; the printed circuit board is cut to obtain a cut sample, the The cut sample includes a 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 special large package IC. The vertical projected area of the packaged IC; a metal foil is provided, and the cut sample is wrapped with the metal foil to form a wrapped sample, and the wrapped sample is placed in a constant temperature oven at the first temperature T1 Heating evenly under ambient conditions for 1-2 hours; remove the evenly heated coated sample from the constant temperature oven, remove the metal foil, and then place the cut sample on a heating plate with a second temperature T2 above, the cut printed circuit board of the cut sample is continuously heated by the heating plate, wherein the second temperature T2 is greater than the first temperature T1, and 50ºC≦(T2-T1)≦70ºC; and providing a peeling tool, and inserting the peeling 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 board The plates are completely separated.

In the above-mentioned method for removing a special large packaged IC for failure analysis from a printed circuit board, the step of cutting the printed circuit board to obtain a cut sample can be completed by using a mechanical cutting machine or a laser cutting machine.

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

In the above-mentioned method of removing a special large package IC for failure analysis from a printed circuit board, the metal foil is aluminum foil or tin foil.

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

Various 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, which can be embodied in various specific forms. The specific embodiments discussed herein are illustrative only and are not intended to limit the scope of the present invention.

Example

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

First, referring to FIG. 1A, a printed circuit board 100 as shown in a top view of FIG. A special large package IC 110 , the special large package IC 110 is fixed on the first surface of the printed circuit board 100 by solder 150 .

Next, referring to FIG. 1B , the printed circuit board 100 is cut to obtain a cut sample 200 as shown in FIG. 1C-1 and FIG. 1C-2 . Wherein, Fig. 1C-2 is a sectional view according to the section line I-I' of the top view of Fig. 1C-1. As shown in Figure 1C-1 and Figure 1C-2, the cut sample 200 includes a cut printed circuit board 100' and a first solder 150 fixed to the cut printed circuit board 100'. 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 completed by, for example but not limited to, a mechanical cutting machine or a laser cutting machine, wherein the mechanical cutting machine is such as but not limited to an electric saw.

Next, referring to FIG. 1D , a metal foil 300 is provided, and the cut sample 200 is wrapped with the metal foil 300 to form a wrapped sample 350 . Then, as shown in FIG. 1E , the coated sample 350 is placed in a constant temperature oven 400 and uniformly heated at the first temperature T1 for 1-2 hours. 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 200°C and 220°C.

Then, referring to FIG. 1F, the evenly heated coated sample 350 is removed from the constant temperature oven 400, and after removing the metal foil 300, the cut sample 200 is placed in a second temperature T2. On the heating plate 500, the cut printed circuit board 110' of the cut sample 200 is continuously heated by the heating plate 500 via 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 is completely separated from the cut printed circuit board 100 ′ as shown in FIG. 1H , so as to facilitate subsequent failure analysis of the special large package IC 110 . The stripping tool 600 used in this embodiment can be, for example but not limited to, a metal sheet, a blade or a flathead screwdriver

To sum up, the method disclosed by the present invention for unloading a special large packaged IC for failure analysis from a printed circuit board is to uniformly heat the cut sample containing the packaged IC, so that it is fixed on the printed circuit board by soldering tin. The special large 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, which is beneficial to the follow-up failure analysis of the special large packaged IC.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Anyone skilled in this 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 defined by the scope of the appended patent application.

100: Printed circuit board 100A: first surface 100B: second surface 100': Trimmed PCB 110: Special large package IC 150: solder 200: cut sample 300: metal foil 350: coated sample 400: constant temperature oven 500: heating plate 600: stripping tool I-I': hatching

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

100': Trimmed PCB

110: Special large package IC

150: solder

200: cut sample

500: heating plate

600: stripping tool

Claims (6)

A method for removing a special large packaged IC for failure analysis from a printed circuit board, the steps of which include: A printed circuit board is provided, the printed circuit board has opposite first and second surfaces, and the first surface contains a special large package IC, and the special large package IC is fixed to the printed circuit board by a solder on the first surface; cutting the printed circuit board to obtain a cut sample, the cut sample includes a cut printed circuit board and the special large package IC fixed on the cut printed circuit board, and the cut The vertical projected area of the cut printed circuit board is slightly larger than that of the particular large packaged IC; Provide a metal foil, and use the metal foil to wrap the cut sample to form a wrapped sample, and place the wrapped sample in a constant temperature oven, and heat it uniformly at the first temperature T1 environment for 1~2 Hour; The uniformly heated coated sample is removed from the constant temperature oven, and after removing the metal foil, the cut sample is placed on a heating plate with a second temperature T2, so that 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 50ºC≦(T2-T1)≦70ºC; and providing a peeling tool, and inserting the peeling 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 board The printed circuit board is completely separated. 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 completed by using a mechanical cutting machine or a laser cutting machine . 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 mechanical cutting machine is an electric saw. 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 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 as described in Claim 1, wherein the first temperature T1 is between 200ºC and 220ºC. The method for removing a special large packaged 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-head screwdriver.

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