TW201715675A - Method for checking coated state of flux onto flip chip using a strength difference of reflected light to check the coated state of flux onto a flip chip - Google Patents

Abstract

The present invention relates to a method for checking the coated state of flux onto a flip chip. The method includes the following steps: coating flux onto the bumps of a flip chip; identifying the positions of the bumps of the flip chip and correcting the identified positions; irradiating light having a wavelength range in a specific domain with a high absorbability for the flux onto the bumps of the flip chip; capturing a video or image from photographing the reflected light reflected by the bumps due to the irradiated light ; and reading the obtained video or image for checking the coated state of flux onto the flip chip.

Description

Method for inspecting the state of flux coating of flip chip

The present invention relates to a method for inspecting a flux coating state of a flip chip, and more particularly to irradiating light having a wavelength range of a specific region having the strongest absorption of the flux, thereby reflecting light reflected according to the reflected light. A method of checking the state of flux coating of a flip chip by the difference in intensity.

In recent years, with the development of electronic communication technologies, electronic devices are increasingly becoming smaller and lighter. Therefore, electronic components (for example, semiconductor wafers) built in various electronic devices must satisfy high integration and ultra-small size.

Therefore, the surface mounting technology for mounting a high-density, ultra-small surface mount component (SMD: Surface Mount Device) to a printed circuit board (PCB: Printed Circuit Board, hereinafter, referred to as " substrate " ) Research is still active today.

As such a surface mounting technology, instead of the conventional bonding technique, a bump is used as a semiconductor wafer. The die of the die and the flip chip technology of the substrate are connected.

A flip chip is a mounting board that can mount an electronic device or a semiconductor wafer directly to a substrate in a face-down configuration.

When the flip chip is mounted on the substrate, electrical connection can be realized by forming conductive bumps on the surface of the wafer, and when the wafer is mounted on the substrate, the wafer is mounted in an inverted state, so It is a flip chip.

Flip-chips do not require wire bonds, so flip-chips are significantly smaller in size than conventional wire-bonding processes. Further, in the wire bonding, the bonding between the wafer of the bonding wire and the substrate is performed one by one, and conversely, in the flip chip, a plurality of bonding can be performed at the same time, and therefore, compared to the bonding wire The cost of wafers, flip-chips will be reduced, and the flip-chip bonding length is shorter than that of wire-bonded wafers, so performance will also be improved.

Hereinafter, a procedure for attaching a flip chip to a substrate according to the flip chip technique described above will be briefly described.

First, a bumping process is performed, that is, the wafer is separated and taken out from the wafer, and the wafer is flipped to reverse the position of the upper and lower surfaces.

After that, a reflow process is performed, that is, a placement machine The head moves the flipped wafer to a predetermined position after it is adsorbed, and heats the face containing the bumps as needed.

At this time, in order to improve the bonding property between the substrate and the wafer, a Fluting procedure, that is, a bump transfer flux (Flux) to the wafer is performed.

Thereafter, a procedure is performed to identify the pad on the substrate as a predetermined position at which the wafer is to be mounted by using camera vision, thereby identifying the position of the bump and causing the bump to abut the pad for mounting (Mounting) ) wafer.

Finally, heating is performed by reflow to bond the substrate and the wafer, and underfill is performed by coating epoxy, and curing is performed by heat or the like to protect the wafer.

In the flip chip process as described above, when the fluxing process for transferring the flux to the wafer bump is performed, it may happen that the flux cannot be normally applied to the bump of the wafer, in which case the wafer does not have The possibility of bonding to the substrate normally is large, and accordingly, there may be a problem of producing defective electronic components.

In this regard, in the prior art, various methods for checking whether a flux is normally applied to a wafer bump have been proposed as follows: for example, after the wafer is immersed in a container having a flux, The camera is used to photograph the bump marks of the flux in the container, and the flux is coated or not. However, in this method, since the flux is composed of a liquid, the trace will disappear instantaneously, which makes it difficult. To easily check the problem of flux application to the wafer bumps.

In addition, there is also a technique of adding an identifiable other additive to the flux to enable the recognition process to be easily performed, however, there may be a problem of the flux property change for the technique.

In addition, there has been proposed a method of inspecting the application of flux to the wafer bump by using a camera to capture a video or image obtained by applying a flux to a bump state of a wafer. However, in this case, since the flux is a colorless liquid, in order to correctly judge the state in which the flux is applied to the bump of the wafer, that is, a camera having a lens having a high price is required, there is a problem that a cost burden occurs. .

Advanced technical literature

Patent Document 1: Korean Patent No. 10-1377444

Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-041758

The present invention has been made in view of the above various problems, and a technical object to be solved by the present invention is to provide a method for inspecting a flux coating state of a flip chip, which is convex to a flip chip coated with a flux. Pointing, illuminating the light having a wavelength range of a specific region that the flux can absorb most strongly, according to which the light intensity of the light reflected from the bump coated with the flux and the bump not coated with the flux The difference is compared and judged, so that the application of the flux can be more easily checked.

In addition, another technical problem to be solved by the present invention is A method for inspecting a flux coating state of a flip chip, which method is used to determine a flux coating state by using a calibration result of a flip chip position impregnated with a flux and a size information of a nozzle By searching the area, it is possible to prevent the occurrence of the coating state of the flux from being different depending on the size of the bump or the size and shape of the nozzle.

The subject matter of the present invention is not limited to the above-described problems, and those skilled in the art should be able to easily understand other problems not mentioned based on the description below.

The method of inspecting a flux coating state of a flip chip according to an embodiment of the present invention may include the steps of: applying a flux to a bump of a flip chip; identifying a bump position of the flip chip, and correcting the location a recognized position; illuminating the bump of the flip chip with illumination light having a wavelength range of a specific region having a higher absorption rate of the flux; and reflecting the reflection from the bump by the illumination light Light is taken to acquire a video or image; and, the captured video or image is read, and the state of application of the flux to the bump of the flip chip is checked.

Preferably, the specific region has a wavelength range in which a wavelength range in which the absorption rate of the flux exhibits one of a plurality of peaks as a function of wavelength changes.

Here, it is preferable to set a search area from the bumps of the flip chip and acquire a video or image of the reflected light reflected from the bump located in the search area.

In this case, the setting of the search area is performed based on the position of the bump, the corrected information, and the size information of the nozzle that adsorbs the flip chip.

In addition, the method may include the steps of: extracting an average light intensity value of the bump located in the search area, and comparing the extracted average light intensity value with a preset and input reference light intensity value, thereby determining The flux is good or bad for the coated state of the flip chip bumps.

Here, if the preset reference light intensity value is greater than the average light intensity value of each bump in the search area, it can be determined that the flux is coated on the flip chip bump. If the preset reference light intensity value is less than the average light intensity value of each bump in the search area, it may be determined that the flux is poorly coated with respect to the bump of the flip chip.

Further, the search area is set to be reset based on the position of the bump, the corrected information, and the size information of the nozzle that adsorbs the flip chip.

Further, preferably, the predetermined reference light intensity value is input before the step of extracting the average light intensity value of the bump located in the search area.

Moreover, the wavelength range of the specific region may be a wavelength range of a region of 400 nm to 500 nm, or a wavelength range of the specific region may be provided by arranging a polarizing film at a position through which the illumination light is transmitted. Surrounded by light.

Other specific matters of the present invention are included in the detailed description and the drawings.

According to the flux coating state inspection method of the flip chip according to the embodiment of the present invention, the present invention can provide the effect that the bump irradiation of the flip chip coated with the flux enables the flux to be absorbed most strongly. The light in a specific region wavelength range can be more easily checked for the flux according to the difference in light intensity between the bumps coated with the flux and the bumps not coated with the flux. Overridden.

Further, according to the flux coating state inspection method of the flip chip according to the embodiment of the present invention, the present invention can also provide the following effects: the position correction result of the flip chip impregnated with the flux and the size information of the nozzle, And re-setting the search area for judging the coating state of the flux, can prevent the occurrence of the coating state of the flux, and the result is different depending on the size of the flip chip bump or the size and shape of the nozzle, thereby The inspection of the coating state of the flux can be performed more accurately.

The effects according to the present invention are not limited to those described above, and more diverse effects will be included in the present specification.

110‧‧‧ nozzle

116‧‧‧Flip Chip

118‧‧‧ bumps

120‧‧‧Bumped front end of flat shape

1 is a view sequentially showing, in order, a flux coating state for inspecting a flip chip according to an embodiment of the present invention. A diagram of the method's surface mounter.

2 is a sequence diagram showing, in order, a method of inspecting a flux coating state of a flip chip in accordance with an embodiment of the present invention, in accordance with an embodiment of the present invention.

Fig. 3 is a sequence diagram showing the method of judging the state of coating by inspecting the state of coating of the flux of the flip chip in order.

Fig. 4 is a view schematically showing the relationship between the execution of the fluxing program in a state where the nozzle sucks the flip chip.

Figs. 5a and 5b are diagrams schematically showing a flux-based shape of the bump located inside the nozzle area and the bump outside the nozzle area in Fig. 4.

Fig. 6 is a graph showing the measurement results of the absorption spectrum of the flux in order to confirm the wavelength range region of the light which the flux can absorb most strongly.

Fig. 7 and Fig. 8 are diagrams showing judgment results of a method of inspecting a flux coating state of a flip chip according to an embodiment of the present invention.

Advantages and features of the present invention, as well as methods for achieving the same, will become more apparent. However, the present invention is not limited to the embodiments disclosed below, which may be implemented in various forms that are different from each other, but the purpose of providing the present embodiment is to completely disclose the present invention and to have the usual technical field to which the present invention pertains. A person skilled in the knowledge can fully understand the scope of the present invention, and The description is only defined by the categories described in the scope of the patent application. Throughout the specification, the same reference symbols are used to refer to the same constituent elements.

Further, the embodiments described in the present specification will be described with reference to cross-sectional views and/or schematic drawings which are ideal schematic views of the present invention. Thus, the form of the schematic may be modified depending on manufacturing techniques and/or tolerances and the like. Further, in the respective drawings shown in the present invention, the respective constituent elements may be enlarged or reduced in consideration of convenience of explanation. Throughout the specification, the same reference symbols refer to the same constituent elements.

Hereinafter, a preferred embodiment of the flux coating state inspection method of the flip chip according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram showing, in order, a surface mount technical program including a method for inspecting a flux coating state of a flip chip according to an embodiment of the present invention.

As shown, the surface mount technique includes engineering that uses a pick-up head with a pick-up to pick-up a flip-chip pick-up project placed on a die shuttle; and, for a fluxing project, A flux is applied to the bump surface of the flip chip that is picked up.

If the flux is applied to the bump surface of the flip chip by the fluxing process, the flip chip is bonded to the substrate after the positional correction of the flip chip, thereby achieving mounting.

At this time, the flux applied to the bump surface of the flip chip The function of flip chip bonding to the substrate is exercised.

Therefore, if the flux is not normally applied to the bumps of the flip chip by the fluxing process, the flip chip cannot be bonded to the substrate, eventually producing defective electronic components.

In order to solve the problem of producing defective electronic components as described above, the present invention proposes a method of inspecting a flux coating state of a flip chip.

2 is a flow chart showing, in order, a method of inspecting a flux coating state of a flip chip according to an embodiment of the present invention; and FIG. 3 is a view showing an inspection of a flux coating state of a flip chip in order. A flow chart of a method of determining the state of application.

First, as shown in FIG. 2, the flux coating state inspection method of a flip chip according to an embodiment of the present invention includes the steps of: picking up a flip chip having a plurality of bumps formed on one side from a die shuttle (S10) The flux is applied to the bump surface (S20) by immersing the flux on the bump of the picked flip chip.

Further, the method further includes the steps of: photographing the position of the bump by the camera in a state where the illumination portion irradiates the bump coated with the flux with the first illumination light (S30); and identifying the bump by the above-described photographing step (S40).

When the image recognition bump of the bump is captured, the following steps may be included: if the recognition is not normally performed, an error occurs (S50); if the bump is successfully recognized, the flip chip is aligned to the preset position, Thereby the correction of the position is completed (S60).

Further, after the correction of the position of the flip chip (ie, the bump) is completed, the illumination portion irradiates the bump with the second illumination light having a wavelength range of a specific region that the flux can absorb most strongly, in this state. The method may include the steps of: the camera taking the reflected light of the second illumination light reflected from the bump (S70); and checking the coating state of the flux of the bump by the difference in the light intensity of the reflected light (S80).

Here, the first illumination light irradiated by the illumination portion may be: light for improving ambient brightness when photographing the camera in order to recognize the bump of the flip chip; the second illumination light may be: having the strongest flux Light that absorbs a specific range of wavelengths in a specific region. In the following, the second illumination light will be described in detail.

The video or image obtained by capturing the reflected light of the second illumination light can be read by a vision confirmation unit (not shown), and the coating state of the flux can be checked. Figure 3 illustrates the specific inspection method as follows.

If there is a second illumination light of a wavelength range of a specific region that the flux can absorb most strongly, the bump is irradiated to the flip chip by the illumination portion, and in this state, the camera captures the second illumination light reflected from the bump When the light is reflected, the captured video or image can be acquired (S810).

Thereafter, the following steps are performed: setting a search area for checking the coating state of the flux with the acquired video or image (S820).

Figure 4 is a schematic view showing the adsorption of flip chip on the nozzle In the state of performing the fluxing process, it can be seen that the cross-sectional area of the nozzle 110 is relatively smaller than the overall cross-sectional area of the flip chip 116.

Therefore, if the flux pad is contacted while the nozzle 110 is attracted to the flip chip 116, the bump located in the nozzle area is pressed as shown in FIG. 5a due to the pressure contact of the flux pad. The front end of the bump will be deformed into a flat shape 120, and the bump 118 outside the area of the nozzle 110 does not form a crimp to the flux pad, so as shown in Fig. 5b, the bump can be maintained Original (ie, spherical).

That is, the bumps located in the area of the nozzle 110 can normally achieve the application of the flux, and conversely, the bumps outside the area of the nozzle 110 may not properly achieve the application of the flux.

Therefore, in the step of setting the search area (S820), it is preferable to input the size information of the nozzle 110 and the corrected information of the position of the flip chip 116 (S830) to set the search area.

For example, the size of the nozzle 110 is not fixed, and various sizes of nozzles can be used. Therefore, in the process for checking the flux coating state of the bumps 118, the setting for the search area can be based on the nozzle 110. The size information and the position of the flip chip 116 are different by the input of the corrected information (S830).

As described above, if the search area for checking the coating state of the flux to the bump is set (S820), the step of inputting the preset reference light intensity value (S840) may be performed.

In the method of inspecting the flux coating state of the flip chip according to the embodiment of the present invention, the step (S840) of inputting the predetermined reference light intensity value after the search region setting step (S820) has been performed as an example. Illustratively, however, this is merely an example, and this step can be performed in any step as long as it is before the average light intensity value extraction step (S850) of each bump in the search area described below.

Further, after the search area setting step (S820) is performed, the step of extracting the average light intensity values of the respective bumps in the search area may be performed (S850).

The step of extracting the average light intensity value of each bump in the search area as described above (S850) can be extracted by reading a video or image obtained by photographing the reflected light, that is, the reflection As described above, the light system illuminates the second illumination light toward the bump and reflects the reflected light from the bump.

The second illumination light of the illumination portion can be illuminated from a source of light in a wavelength range of a particular region that is applied to the bumps of the flip chip that is most strongly absorbed by the flux.

Figure 6 is a graph showing the measurement results of the absorption spectrum of the flux in order to confirm the wavelength range region of the light having the strongest absorption of the flux by the applicant of the present invention, as shown in Fig. 6, the flux to the light The amount of absorption increases as the wavelength range gradually increases from the wavelength range of the 300 nm region, especially at a wavelength of about 420 nm at which the first peak is located. It has the highest absorption rate of light.

In addition, it can be seen that as the wavelength range gradually increases from the wavelength range of about 420 nm, the absorption of light first decreases, and then the absorption rate of light is also in the wavelength range of about 465 nm where the second peak is located. Relatively high.

Therefore, in the flux coating state inspection method of the flip chip according to the embodiment of the present invention, the second illumination light can be irradiated by the light source having a wavelength range of a region of 400 nm to 500 nm.

However, it is of course also possible to use a light source having a wavelength range other than the wavelength range of the region, and to arrange a polarizing film or the like to illuminate light of a wavelength range (400 nm to 500 nm) of the above region.

As described above, the second illumination light can be irradiated to the bump of the flip chip by the wavelength light source having the specific region where the flux can be most strongly absorbed, and the light intensity of the reflected light reflected by each bump in the search region is extracted and extracted as The average value is (S850), and the following step (S860) is performed: the average light intensity value of each of the bumps in the extracted search area is compared with the reference light intensity value that is preset and input.

At this time, if the reference light intensity value input as being read in advance is larger than the average light intensity value of each bump in the search area, it can be determined that the coating state of the flux is good (S870), and conversely, if When the reference light intensity value read as being preset and input is smaller than the average light intensity value of each bump in the search area, the coating state of the flux can be determined. Bad (S880).

As described above, the second illumination light is light having a wavelength of a specific region that the flux can absorb most strongly, and therefore, part of the light is absorbed by the flux applied to the bumps of the flip chip.

For example, assuming that the light intensity of the second illumination light is 100, the light intensity of the light reflected from the bumps of the flip chip is absorbed as part of the light is absorbed by the flux applied to the bumps of the flip chip. Will drop below 100.

Conversely, in the case where the bumps of the flip chip are not coated with the flux, the amount of light reflected from the bumps of the flip chip will remain at the original 100.

Therefore, if the reference light intensity value input for reading is set to be larger than the average reflected light intensity value of each bump in the search area, it indicates that the flux is normally applied to each bump in the search area, thereby absorbing A part of the light of the second illumination light, according to which, it can be judged that the coating state of the flux is good.

On the contrary, if the reading reference light intensity value input for the preset is smaller than the average reflected light intensity value of each bump in the search area, it indicates that the flux is not normally applied to the bumps in the search area, thereby The second illumination light is directly reflected, and accordingly, it can be judged that the coating state of the flux is poor.

FIG. 7 and FIG. 8 are views showing a judgment result displayed by the visual confirmation unit by the flux coating state inspection method of the flip chip according to an embodiment of the present invention, wherein the seventh figure indicates the search. The average reflected light intensity value of each bump in the region is larger than the value of the light intensity input in advance, so that the flux is not normally coated (refer to the AA ' line light intensity) map; the eighth figure indicates the search area. The average light intensity value of each bump in the inside is smaller than the light intensity value input in advance, and thus the flux is normally coated (refer to the light intensity of the BB ' line).

If the inspection result of the flux coating state of the flip chip is checked by the inspection method as described above, it is judged that the flux coating state is good, the flip chip is transferred to the subsequent process, and conversely, if it is judged to be the coating state If it is not good, the fluxing process for the flip chip is re-executed, thereby eliminating the problem of excessive production of defective electronic components.

In addition, according to another embodiment of the present invention, in the method of inspecting the flux coating state of a flip chip, the search area can be reset according to the position of the flip chip corrected and the information of the size of the nozzle, thereby The search area for checking the application state of the flux to the bumps of the flip chip can be changed according to the nozzles of different sizes, so that the coating state of the flux can be more accurately checked.

It is to be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Therefore, it is to be understood that the above-described embodiments are illustrative in all aspects and are not limiting. This hair The scope of the patent is expressed by the scope of the patent application, and is not limited to the above detailed description, and all the changes or changes derived from the equivalent concepts and scopes of the patent application. Morphology is to be construed as being included in the scope of the present invention.

110‧‧‧ nozzle

116‧‧‧Flip Chip

118‧‧‧ bumps

Claims (10)

A method for inspecting a flux coating state of a flip chip, comprising the steps of: (a) applying a flux to a bump of a flip chip; (b) identifying a bump position of the flip chip, and correcting the location Identifying the position; (c) illuminating the bump of the flip chip with illumination light having a wavelength range of a specific region having a high absorption rate for the flux; (d) from the illumination light by the illumination light The reflected light reflected by the bump is photographed to acquire a video or an image; and (e) reading the acquired video or image to check a coating state of the bump for the flip chip, wherein The wavelength range of the specific region is such that the absorption rate for the flux is a wavelength range of one of a plurality of peaks displayed as a function of wavelength. The method of inspecting a flux coating state of a flip chip according to claim 1, wherein the step (d) has the following procedure: setting a search area from the bump of the flip chip, and acquiring A video or image of reflected light reflected from a bump located within the search area. Flux coating of flip chip as described in claim 2 The state inspection method, wherein the setting of the search area is performed based on the position of the bump, via corrected information, and information for adsorbing the size of the nozzle of the flip chip. The method for inspecting a flux coating state of a flip chip according to claim 2, comprising the steps of: extracting an average light intensity value of a bump located in the search area, and extracting the extracted average The light intensity value is compared with a preset reference light intensity value to determine whether the flux is good or bad for the coated state of the bump of the flip chip. The method for inspecting a flux coating state of a flip chip according to the fourth aspect of the invention, wherein the predetermined reference intensity value is greater than an average light intensity value of each bump in the search area. Then, it is judged that the flux is coated well with respect to the bump of the flip chip. The method for inspecting a flux coating state of a flip chip according to the fourth aspect of the invention, wherein the predetermined reference intensity value is less than an average light intensity value of each bump in the search area. Then, it is judged that the flux is poor in the coating state of the bump of the flip chip. The inspection method of the flux coating state of the flip chip according to the second aspect of the invention, wherein the setting of the search area is corrected information according to the position of the bump and the flipping is performed. The size of the nozzle of the wafer is re-set. Flux-coated flux coating as described in claim 4 The method of checking the state, wherein the predetermined reference light intensity value is input before the step of extracting the average light intensity value of the bump located in the search area. The method for inspecting a flux-coated state of a flip chip according to the first aspect of the invention, wherein the specific region has a wavelength range of between 400 nm and 500 nm. The method for inspecting a flux-coated state of a flip chip according to the first or the ninth aspect of the invention, wherein the polarizing film is disposed at a position through which the illumination light is transmitted, thereby providing the specific Light illumination in the wavelength range of the region.