TWI553751B - Method for cleaning molding flash of semiconductor package - Google Patents

Description

Decapsulation method for packaged wafer

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of removing a packaged wafer, and more particularly to a method for removing a package for a tetragonal planar lead package wafer.

In the prior art, a QFN (quad flat no-lead) chip packaging process is first performed on a substrate (a lead frame strip) to form a plurality of lead frame units, each of which includes a wafer holder and a plurality of rows of pins; A semiconductor wafer is fixed on the upper surface of the wafer holder via a die attach step, and a wire bond or a pre-formed electrical connection component (such as a flip chip) is interposed between the wafer and each of the leads. Blocking) to form an electrical connection; attaching a barrier film on the lower surface of the substrate; then, holding the substrate with a pair of upper and lower molds, and injecting the molten colloidal material into the molten state by plastic injection molding The mold cavity of the mold covers the wafer, the bonding wire and the pin on the upper surface side of the substrate, and forms a basic package outline of the semiconductor package structure after being cooled and formed; finally, the barrier film is removed to complete the The molding process of the wafer packaging process; subsequent, and can be cut to become a plurality of QFN packages.

However, in the process of forming the existing package colloid, it is easy to cause a melting flash defect, that is, a part of the flowing colloid accidentally enters between the barrier film and the lower surface of the wafer holder (or the lead), so Improper coverage of the wafer holder or pin lower surface after the program Excessive residual rubber burrs, such that the wafer holder or pins can not completely expose the lower surface, resulting in heat dissipation or poor electrical contact, indirectly causing the yield of the wafer after packaging to decline.

In view of the above-mentioned shortcomings, the applicant is in the method of removing the glue of the packaged wafer of the application of the invention No. 201513236, by performing an image analysis operation on the image of a substrate by an arithmetic unit and comparing with the template to detect the wafer of the substrate. The portion of the socket and the lead portion that is covered by the residual glue due to the overflow of the glue, and then the laser trace of a laser generator is used to ablate and remove the residual glue to avoid the electrical contact failure of the lead portion of the wafer.

However, when the image analysis operation is performed, the wafer holder and the lead portion are synchronously compared with the pattern, which is more likely to be affected by the position error caused by the wafer holder and the lead portion during the configuration. Degree, thus it is impossible to accurately identify the part covered by the residual glue; further, each lead frame unit is defined by a plurality of stamping or etching perforations, and the lead frame is also easier to be compared with the shape of the lead hole due to the shape of the lead hole. Small and densely arranged to effectively identify the part covered by the residual glue.

Therefore, it is necessary to provide an improved method of removing the packaged wafer to solve the problems of the conventional technology.

The main purpose of the present invention is to provide a method for removing a packaged wafer, which can effectively improve the removal of glue by separately positioning and removing the glue pins of the wafer holder and the lead portion in the package block in two stages. The accuracy.

In order to achieve the above object, the present invention provides a method for removing a packaged wafer, comprising a photographing step, a wafer holder positioning step, a wafer holder residue detecting step, a pin portion positioning step, and a lead portion. Residue detection step and a de-glue step; the shooting step utilizes a The photomicrograph device captures a substrate image of a lead frame substrate after the chip is packaged, wherein the substrate image comprises a plurality of package blocks arranged adjacent to each other, each package block having a wafer holder and a plurality of rows of leads a leg portion and a gel portion, the pin portions respectively surrounding the wafer holder, and each of the lead portions has a plurality of pins, and the glue portion fills the pin portions and the wafer holder The upper surface and the two; the wafer bearing positioning step uses an arithmetic unit to load the substrate image, and performs image analysis to locate the position of the wafer holder in the package block; the wafer bearing residual glue detection The measuring step uses the computing unit to compare the wafer holders of the package blocks with a wafer holder sample image to detect residual glue covering the wafer holders of the package blocks; The positioning step is performed by the computing unit to perform image analysis to locate the position of the pin portion in the package block; the pin portion residual glue detecting step uses the operation unit to pin each pin of each row with at least One pin sample image ratio To detect residual glue covering the pins of the pin portions; the de-glue step uses a laser generator to remove the wafer holders of the package blocks and the pins of the pin portions Residual glue.

In an embodiment of the present invention, the computing unit performs image analysis by comparing the plurality of positioning portions of the substrate image with a positioning portion sample image to locate the packaging regions. The location of the wafer holder within the block.

In an embodiment of the present invention, in the process of detecting the residual adhesive of the wafer, the wafer holder of the package block and the sample image of the wafer holder are compared by using pixel values of the wafer holder to detect Residual glue covering the wafer holders of the package blocks.

In an embodiment of the present invention, in the pin portion positioning step, the operation unit performs image analysis to locate the positions of the four side lengths of the wafer holders of the package blocks, and then calculates the packages. The position of the pin portion of the block.

In an embodiment of the present invention, in the pin portion positioning step, after the positions of the four side lengths of the wafer holders of the package blocks are positioned, the wafer holder periphery is separately estimated according to the side lengths. Four rectangular regions, each rectangular region is divided into a plurality of segments, and a plurality of pins of each row of pin portions are respectively located in corresponding segments, thereby calculating a pin portion in the package blocks The position of the pin.

In an embodiment of the present invention, in the step of removing the glue, the laser generator performs laser ablation according to a center of the section at the corresponding pin position to remove the cover on the pin. Residue.

In an embodiment of the present invention, in the step of detecting the residual portion of the lead portion, the pin of the pin portion of the package block is compared with the sample image of the pin by using the pixel value of the pin. Detecting residual glue covering the pins of the pins.

In an embodiment of the present invention, in the step of detecting the residual portion of the lead portion, the pins of the four rows of the pin portions of the package blocks respectively correspond to the image of the four pin samples in different orientations for pixel The values are compared.

In an embodiment of the invention, after the photographing step, an automatic dimming step is further included to detect the intensity of the light source of the photomicrography device by detecting the color gradation of the substrate image.

In an embodiment of the present invention, before the photographing step, a pre-stored step is further included, and the wafer holder sample image and the pin sample image are stored in the operation unit.

As described above, the present invention can position the pins of the wafer holder and the lead portion of the package block in two stages by using the obtained substrate image, thereby effectively improving the accuracy of positional positioning; Using the wafer holder sample image and the pin sample image respectively Pixel value comparison between the wafer holder and the pin can also effectively identify the portion covered by the residual glue, thereby improving the efficiency of removing the packaged wafer.

S201‧‧‧ Pre-existing steps

S202‧‧‧Photographing steps

S203‧‧‧Automatic dimming step

S204‧‧‧ wafer holder positioning step

S205‧‧‧ wafer holder residue detection step

S206‧‧‧Pin section positioning steps

S207‧‧‧Pin section residual glue detection step

S208‧‧‧Degumming step

100‧‧‧Substrate image

1‧‧‧Package block

11‧‧‧ wafer holder

12‧‧‧Lead Department

121‧‧‧ pin

13‧‧‧Colloid

14‧‧‧ Positioning Department

15‧‧‧Rectangular area

Section 151‧‧‧

21‧‧‧ Positioning sample image

22‧‧‧ wafer holder sample image

23‧‧‧ Pin sample image

1 is a flow chart of a method for removing a packaged wafer according to a preferred embodiment of the present invention; and FIG. 2 is a schematic view of a substrate image of a method for removing a packaged wafer according to a preferred embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 4 is a schematic view showing a sample image of a positioning portion of a method for removing a packaged wafer according to a preferred embodiment of the present invention; FIG. 4 is a view showing a sample of a wafer holder for a method for removing a packaged wafer according to a preferred embodiment of the present invention. 5 is a schematic diagram of dividing a rectangular region into a plurality of segments by a method of removing a packaged wafer according to a preferred embodiment of the present invention; and FIG. 6 is a view of a preferred embodiment of the present invention. Schematic diagram of the pin sample image of the decapsulation method of the packaged wafer.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as upper, lower, top, bottom, front, rear, left, right, inner, outer, side, surrounding, central, horizontal, horizontal, vertical, longitudinal, axial, Radial, uppermost or lowermost, etc., only refer to the direction of the additional schema. Therefore, the directional terminology used is for the purpose of illustration and understanding of the invention.

Referring to FIG. 1 , a method for removing a packaged wafer according to a preferred embodiment of the present invention is performed on a substrate used in a known quad flat no-lead package (QFN package) process. The substrate (the lead frame strip) has a plurality of wafer holders and lead portions, and the plurality of semiconductor wafers are disposed on the corresponding wafer holders, and the upper surfaces of the wafer holders and the lead portions and both A colloid is coated between them to achieve an insulating effect. The method for removing the packaged wafer includes a pre-storing step S201, a photographing step S202, an automatic dimming step S203, a wafer holder positioning step S204, a wafer holder residue detecting step S205, and a pin portion positioning step. S206, a lead portion residual glue detecting step S207 and a glue removing step S208, the detailed structure, assembly relationship and operation principle of each element will be described in detail below.

Referring to FIG. 1 , in the pre-storing step S201, a positioning portion sample image 21 (see FIG. 3 ), a wafer holder sample image 22 (see FIG. 4 ), and a plurality of pin sample images are first introduced. 23 (see FIG. 6) and stored in an arithmetic unit (not shown), wherein the positioning portion sample image, the wafer holder sample image 22, and the pin sample images 23 are template images drawn by software.

Referring to FIGS. 1 and 2, in the photographing step S202, a substrate image 100 of a lower surface of the packaged lead frame substrate of the semiconductor wafer is obtained by using a microphotography device (not shown). The substrate image 100 (ie, the lower surface of the lead frame substrate) includes a plurality of package blocks 1 arranged adjacent to each other, each package block 1 having a wafer holder 11, a plurality of rows of pins 12, and a colloid Each of the lead portions 12 surrounds the wafer holder 11 and each of the lead portions 12 has a plurality of pins 121. The glue portion 13 fills the lead portions 12 and the wafer holder. The upper surface of 11 and between the two.

Referring to FIGS. 1 and 2, in the automatic dimming step S203, the color gradation of the substrate image 100 is detected to adjust the intensity of a light source of the photomicrography device, and then The lead frame substrate is photographed to obtain a substrate image 100 of a preset value that can conform to the color gradation.

Referring to the first, second, and third figures, in the wafer carrier positioning step S204, the substrate image 100 is loaded by the computing unit, and image analysis is performed to locate the wafer holders in the package blocks 1. In the embodiment, the computing unit performs the image analysis system to compare the plurality of positioning portions 14 of the substrate image 100 with a positioning portion sample image 21, by calculating the positioning portion 14 and the wafer bearing The relative positions of the seats 11 position the positions of the wafer holders 11 within the package blocks 1.

Referring to FIGS. 1, 2, and 4, in the wafer carrier residue detecting step S205, the wafer holder 11 of the package block 1 and the wafer holder sample image 22 are used by the arithmetic unit. Aligning to detect residual glue covering the lower surface of the wafer holder 11 of the package block 1; in this embodiment, the wafer holder 11 of the package block 1 and the wafer holder The sample images 22 are aligned using their own pixel values to detect residual glue covering the lower surface of the wafer holder 11 of the package block 1; for example, the pixel value of one of the wafer holders 11 The difference in pixel values of the wafer holder sample image 22 is greater than a predetermined value, indicating that the lower surface of the wafer holder 11 has a plurality of residual glue.

Referring to the first, second, and fifth figures, in the pin portion positioning step S206, the image unit is used to perform image analysis to locate the position of the lead portion 12 in the package block 1. In this embodiment, The operation unit performs image analysis to locate the positions of the four sides of the wafer holder 11 of the package block 1, and then calculates the four rectangular regions 15 around the wafer holder 11 according to the sides. (Fig. 5 shows only one of them), in which each rectangular area 15 is divided into a plurality of sections 151, and the plurality of pins 121 of each row of the pin portions 12 are respectively located in the corresponding segments 151, thereby calculating the positions of the pins 121 of the pin portions 12 in the package blocks 1.

Referring to the first, second, and sixth figures, in the lead portion residual glue detecting step S207, the arithmetic unit is used to perform the pin 121 of each row of the pin portion 12 and the at least one pin sample image 23. Aligning to detect the residual glue covering the lower surface of the pin 121 of the pin portion 12; in this embodiment, the pins 121 of the four rows of the pin portions 12 of each package block 1 are respectively The four pin sample images 23 (see FIG. 6) corresponding to different orientations are compared; for example, the pin 121 of the upper pin portion 12 and the pin sample above the sixth figure of each package block 1 The image 23 is compared; in addition, the pin 121 of the pin portion 12 of the package block 1 and the pin sample image 23 are compared by their own pixel values to detect coverage on the pin portions. Residual glue on the lower surface of pin 121 of 12.

Referring to FIGS. 1 and 2, in the de-glue step S208, the wafer holder 11 of the package block 1 and the lead portions 12 are removed by a laser generator (not shown). Residual glue on the lower surface of the pin 121; in this embodiment, the laser generator uses a sub-Gray shot, and the laser beam generated by the laser generator has a power and a wavelength of 16 to 24 watts, respectively. And 851~1277 nm; the laser generator performs laser ablation according to a center obtained by the opposite side operation of the wafer holder 11 to remove the residual glue covering the lower surface of the wafer holder 11, and At a center of the section 151 (see FIG. 5) at the position of the corresponding pin 121, laser ablation is performed to remove the residual glue covering the lower surface of the lead 121.

According to the above structure, first, the lead frame substrate is photographed by the photomicrography device to obtain the substrate image 100, and the position of the wafer holder 11 in the package block 1 is positioned, and the wafer holder is positioned. The sample images 22 are aligned to detect residual glue covering the lower surface of the wafer holder 11 of the package block 1; then, the position of the wafer holder 11 is utilized. The position of the pin 121 of the pin portion 12 in the package block 1 is calculated and located, and then compared with the pin sample image 23 to detect the pin 121 covering the pin portion 12. Residual glue on the lower surface; finally, the residual glue covering the lower surface of the wafer holder 11 and the lead 121 is removed by the laser generator.

With the above design, the present invention can effectively position the substrate holders 11 and the pins 121 of the lead portions 12 in the package blocks 1 in two stages by the obtained substrate image 100. The accuracy of the positional positioning; at the same time, the pixel bearing sample image 22 and the pin sample image 23 are respectively compared with the wafer holder 11 and the pin 121 for pixel value comparison, and the portion covered by the residual glue can be effectively recognized, and further Improve the efficiency of de-glueing the packaged wafer.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

S201‧‧‧ Pre-existing steps

S202‧‧‧Photographing steps

S203‧‧‧Automatic dimming step

S204‧‧‧ wafer holder positioning step

S205‧‧‧ wafer holder residue detection step

S206‧‧‧Pin section positioning steps

S207‧‧‧Pin section residual glue detection step

S208‧‧‧Degumming step

Claims (10)

A method for removing a packaged wafer, comprising: a photographing step of obtaining a substrate image of a lead frame substrate after a chip package by using a microphotography device, wherein the substrate image comprises a plurality of package regions arranged adjacent to each other Block, each package block has: a wafer holder; a plurality of rows of lead portions respectively surrounding the wafer holder, and each row of lead portions has a plurality of pins; and a colloid portion filled with the a lead portion and an upper surface of the wafer holder and between the two; a wafer holder positioning step of loading the substrate image by an arithmetic unit and performing image analysis to locate the wafer holder in the package block a wafer bearing residue detection step, wherein the wafer holder of the package block is compared with a wafer holder sample image by the operation unit to detect a wafer covering the package block Residual glue on the socket; a pin positioning step, the image unit is used to perform image analysis to locate the position of the pin portion in the package block; and a pin portion residual glue detecting step is performed by using the operation unit Each row of pins The pins are compared with at least one pin sample image to detect the residual glue covering the pins of the pin portions; and a de-glue step, using a laser generator to remove the package blocks The wafer holder and the residual glue on the pins of the pins. The method for removing a packaged wafer according to claim 1, wherein in the wafer holder positioning step, the operation unit performs image analysis on the substrate The plurality of positioning portions of the image are compared with a positioning portion sample image to locate the position of the wafer holder in the packaging block. The method for removing a packaged wafer according to the first aspect of the invention, wherein in the wafer carrier residue detecting step, the wafer holder of the package block and the wafer holder sample image utilize the same The pixel values are compared to detect residual glue covering the wafer holders of the package blocks. The method for removing a packaged wafer according to claim 1, wherein in the step of positioning the lead portion, the image unit is used to perform image analysis to locate four sides of the wafer holder of the package block. The position, and thus the position of the pin portion of the package block. The method for removing a packaged wafer according to claim 4, wherein in the pin portion positioning step, the positions of the four side lengths of the wafer holders of the package blocks are positioned, and then according to the The side lengths respectively calculate four rectangular regions on the periphery of the wafer holder, each rectangular region is divided into a plurality of segments, and the plurality of pins of each row of pin portions are respectively located in the corresponding segments, thereby calculating the The position of the pin of the pin portion in the package block. The method of removing a packaged wafer according to claim 5, wherein in the step of removing the glue, the laser generator performs laser ablation according to a center of a section at a corresponding pin position. The residual glue covering the pin is removed. The method for removing a packaged wafer according to claim 1, wherein in the step of detecting the residual portion of the lead portion, the pin of the package portion of the package block is The pin sample image is compared using its own pixel values to detect the residual glue covering the pins of the pins. The method for removing a packaged wafer according to claim 7, wherein in the step of detecting the residual portion of the lead portion, the pins of the four rows of the lead portions of the package block respectively correspond to different orientations. Four pin sample images are compared for pixel values. The method for removing a packaged wafer according to claim 1, wherein after the photographing step, an automatic dimming step is further included, and the color gradation of the substrate image is detected to adjust the photomicrography device. The intensity of a light source. The method for removing a packaged wafer according to claim 1, wherein before the photographing step, a pre-stored step is further included, and the wafer holder sample image and the pin sample image are stored in the operation unit.