CN115295428A - Method for carrying out chip mounting by utilizing scrapped substrate and light-emitting plate - Google Patents

Abstract

The invention relates to the technical field of chip packaging, in particular to a chip mounting method and a light-emitting board using a scrap substrate. The chip mounting method includes the following steps: providing a scrapped substrate and a chip, and solder paste exists in the soldering area of the substrate; performing first reflow soldering on the substrate to melt the solder paste in the soldering area; Flux is dispensed; the chip is bonded to the soldered area after the flux is dispensed. The chip mounting method of the present invention solves the technical problem that the chip cannot be mounted on the substrate which cannot be printed twice because the solder paste is printed on the soldering area. The light-emitting panel of the present invention has the same beneficial effects as the chip mounting method, which will not be repeated here.

Description

Chip mounting method and light-emitting panel using scrap substrate

【Technical field】

The invention relates to the technical field of chip packaging, in particular to a chip mounting method using scrap substrates and a light-emitting panel.

【Background technique】

When the chip is packaged, if the printing solder paste process or the reflow soldering process is not well controlled, it will lead to bad conditions of the solder paste on the soldering area of the substrate, which will cause the substrate to be scrapped and cannot continue to attach the chip installed technical problems.

【Content of invention】

In order to solve the problems in the prior art, the present invention provides a chip mounting method and a light-emitting panel using scrap substrates.

In order to solve the above technical problems, the technical solution provided by the present invention is to provide a chip mounting method using scrap substrates. The chip mounting method includes the following steps:

Provide scrap substrates and chips, where there is solder paste in the soldering area of the substrate;

Carrying out the first reflow soldering to the substrate to melt the solder paste in the soldering area;

Spot-coat flux on the welding area of the substrate after the first reflow soldering;

Die-bonding the chip to the soldering area where the flux has been applied.

Preferably, after the chip is crystal-bonded to the soldering area where the flux has been applied, the method further includes a step of performing a second reflow soldering on the substrate, so as to solder the chip to the soldering area.

Preferably, the surface of the chip in contact with the welding area is provided with a tin-plated layer, and the thickness of the tin-plated layer is 6-18 μm.

Preferably, the flux includes one or more of rosin, tackifier, brightener, and organic solvent, and in the flux, the content of the rosin is 55% to 85% by mass percentage . The content of the tackifier is 1%-6%, the content of the brightener is 8%-17%, and the content of the organic solvent is 8%-17%.

Preferably, before performing the second reflow soldering on the substrate, the method further includes a step of optically inspecting the substrate on which the chips have been bonded.

Preferably, before performing the first reflow soldering on the substrate, a step is further included: spot-coating solder paste with a melting point of 130-180° C. on the soldering area.

Preferably, before performing the second reflow soldering on the substrate, solder paste with a melting point of 130-180° C. is spot-coated on the soldering area where the flux is spot-coated.

Preferably, after spot-coating flux on the soldering area of the substrate after the first reflow soldering, the method further includes a step of performing SPI detection on the solder paste coated with flux.

Preferably, after performing the second reflow soldering on the substrate, a step is further included: applying a sealant layer on the surface of the chip.

Another technical solution of the present invention to solve the above-mentioned technical problems is to provide a light-emitting board, which is made by the above-mentioned mounting method.

Compared with the prior art, a mounting method using scrap substrates provided by the present invention has the following advantages:

1. In the mounting method provided by the embodiment of the present invention, the solder paste in the welding area can be melted by performing the first reflow soldering on the substrate, and then spot-coating flux on the welding area can make the subsequent chip soldering better On the welding area, the chip is finally solidified on the welding area through the crystal bonding technology, thereby completing the chip mounting process. It can be seen that the mounting method provided by the first embodiment of the present invention solves the technical problem that the chip cannot be mounted on the scrapped substrate due to solder paste printed on the soldering area, that is, the mounting method of the present invention can Therefore, the substrate can still realize the function of mounting chips, which can save costs and improve the yield rate of products.

2. The placement method provided by the embodiment of the present invention, through the design of the second reflow soldering on the substrate, after using the solder paste to connect the chip to the welding area, the solder paste is melted by controlling the heating temperature to achieve permanent Bonding, that is, soldering the chip on the pad.

3. The placement method provided by the embodiment of the present invention, through the design of setting the tin-plated layer on the chip and the welding area, firstly, the chip can be better welded on the welding area, that is, the chip can be reduced. The possibility of welding, thus further improving the yield of the product. The second is that when the tin-plated layer of the chip is bonded to the soldering area, there is a certain amount of extrusion between the tin-plated layer of the chip and the soldering area, so that after the second reflow soldering, the chip and the soldering area can be more firmly bonded. . The third is that when the chip is soldered to the welding area, there will be a relative angle offset between the two. After the chip is lit, the chip with the angle offset will emit uneven light and affect the overall luminous effect. It can prevent the possibility of chip tilting, that is, the chips can be arranged and soldered to the welding area according to the preset posture, so as to ensure that after the second reflow soldering, the chips soldered to the substrate can follow the preset state Uniform arrangement.

4. The placement method provided by the embodiment of the present invention, through this design, this flux can show good tin speed, good welding effect and cleaning effect in the welding process, and after welding, the surface of the substrate is relatively weak. More rosin residues can be cleaned with an appropriate cleaning agent to ensure good insulation resistance on the cleaned surface, and the tackifier can greatly increase the viscosity of the welding area, and the brightener can significantly improve the brightness and bonding of the coating in the welding area The strength can greatly improve the stability of the welding area, and the organic solvent can be cleaned with water after the welding work is completed, which not only reduces the production cost of the customer, but also meets the requirements of environmental protection. Therefore, by applying the above-mentioned soldering flux 14 to the soldering area, the first is to clean the surface of the soldering area, which is convenient for subsequent mounting of the chip, the second is to wet the soldering area, and the third is to speed up the welding process. The efficiency can further improve the efficiency of the overall process flow.

5. The placement method provided by the embodiment of the present invention can ensure whether there are missing chips through the design of AOI detection on the substrate before the second reflow soldering of the substrate, thereby further improving the yield of the product.

6. The placement method provided by the embodiments of the present invention can detect the printing area, height, shape, XY offset, bridging and volume of the solder paste printing by designing the SPI detection of the solder paste coated with flux. Consistency, so as to control the quality of solder paste printing and improve the accuracy of subsequent chip soldering.

7. The mounting method provided by the embodiment of the present invention, through the design of spot-coating sealant layer on the surface of the chip, can realize the function of protecting the chip, and can realize the function of different light emission adjustment of the chip.

8. The luminescent panel provided by the embodiment of the present invention has the same beneficial effects as the mounting method of the present invention, which will not be repeated here.

【Description of drawings】

Fig. 1 is a schematic flow chart of a mounting method using scrap substrates provided by the first embodiment of the present invention;

FIG. 2 is a first structural schematic diagram of a scrap substrate provided by the first embodiment of the present invention;

Fig. 3 is a second structural schematic diagram of the scrap substrate provided by the first embodiment of the present invention;

Fig. 4 is a schematic structural view of the scrap substrate provided by the first embodiment of the present invention after the first reflow soldering;

Fig. 5 is a schematic structural view of the discarded substrate provided by the first embodiment of the present invention after being spot-coated with flux;

Fig. 6 is a schematic structural view of a scrap substrate provided by the first embodiment of the present invention after die bonding;

Fig. 7 is a schematic structural diagram of a light-emitting panel provided by the second embodiment of the present invention.

Explanation of the accompanying drawings:

1. Mounting method; 2. Light-emitting board;

11. Substrate; 12. Welding area; 13. Solder paste; 14. Flux; 15. Chip; 16. Alignment point; 21. Substrate; 22. Chip.

【Detailed ways】

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to FIG. 1 , the first embodiment of the present invention provides a chip mounting method 1 using scrap substrates. The chip mounting method 1 includes the following steps:

S1: Provide scrap substrates and chips, and there is solder paste in the soldering area of the substrate;

S2: Perform the first reflow soldering on the substrate to melt the solder paste in the soldering area;

S3: spot-coating flux on the soldering area of the substrate after the first reflow soldering;

S4: Die-bonding the chip to the soldering area where flux has been applied.

It should be noted that referring to FIG. 2 and FIG. 3 , the substrate 11 provided by the first embodiment of the present invention is a board with solder paste 13 printed on the soldering area 12 and cannot be reworked twice. In addition, the substrate 11 is made of insulating materials, such as BT board (Bismaleimide Triazine), FR-4 board, FPC board (Flexible Printed Circuit), etc. In this embodiment, the substrate 11 is described by taking an FPC board as an example. In addition, the chip 15 of the present invention uses a Mini LED chip 15 .

Specifically, please refer to FIG. 4 to FIG. 6. In the chip mounting method 1 provided by the first embodiment of the present invention, the first reflow soldering is performed on the substrate 11. Through this design, the bonding area 12 on the substrate 11 can The solder paste 13 is melted, and then the soldering area 12 after the first reflow soldering is designed to apply flux 14, so that the chip 15 can be better welded on the welding area 12 and can reduce the difficulty of operation. The complexity and the accuracy of chip mounting are improved, thereby improving the efficiency of the overall process flow. Finally, the chip 15 is bonded to one side of the welding area 12 through the die-bonding technology, thereby completing the mounting process of the chip 15 . It can be seen that the mounting method 1 provided by the first embodiment of the present invention solves the technical problem that the chip 15 cannot be mounted on the substrate 11 that cannot be reworked twice because the solder paste 13 is printed on the soldering area 12, that is, Adopting the mounting method 1 of the present invention can make the substrate 11 still realize the function of mounting the chip 15 , which can save costs and improve the yield of products.

It should be noted that the die-bonding technology is an existing technology and will not be repeated here.

Optionally, when the substrate 11 is subjected to reflow soldering for the first time, the reflow soldering equipment adopts temperature zone 10 or temperature zone 13 for reflow soldering.

It can be understood that by using the equipment in the 10 temperature zone or the 13 temperature zone to perform the first reflow soldering design on the substrate 11, since the reflow curve of the equipment in the 10 temperature zone or the 13 temperature zone will be more stable, it can make the substrate 11 The solder paste 13 melts better on the soldering area 12 . As a preferred solution of the first embodiment of the present invention, equipment with 10 temperature zones is used for the first reflow soldering.

Further, before performing the first reflow soldering on the substrate, a step is further included: spot-coating solder paste 13 with a melting point of 130-180° C. on the soldering area 12 . Preferably, solder paste 13 with a melting point of 138-172° C. is used to spot-coat the soldering area 12 .

Understandably, with this design, solder paste is dispensed before the first reflow soldering, so that the solder paste can be cured by the first reflow soldering.

Further, after the chip 15 is solidified on one side of the welding area 12 after the flux 14 has been applied, a step is further included: performing a second reflow on the substrate 11 to solder the chip 15 on the welding area 12 .

Understandably, through the second reflow design of the substrate 11, after using the solder paste 13 to connect the chip 15 to the soldering area 12 on the substrate 11, the solder paste 13 is melted by controlling the heating temperature to achieve permanent Bonding, that is, soldering the chip 15 on the pad 12 .

Further, before performing the second reflow soldering on the substrate, a step is further included: spot-coating solder paste 13 with a melting point of 130-180° C. onto the soldering area 12 spot-coated with flux. Preferably, solder paste 13 with a melting point of 138-172° C. is used to spot-coat the soldering area 12 .

Understandably, with this design, the solder paste is dispensed before the second reflow soldering, so that the solder paste can be cured by the second reflow soldering.

Optionally, when performing the second reflow soldering on the substrate 11 , the reflow soldering equipment adopts temperature zone 10 or temperature zone 13 for reflow soldering.

It can be understood that by adopting the equipment in temperature zone 10 or 13 to perform the second reflow soldering on the substrate 11, since the reflow curve of the equipment in temperature zone 10 or 13 will be more stable, it is possible to make the soldering zone 12 The solder paste 13 on it melts better, so that the chip 15 is better soldered on the pad 12 . As a preferred solution of the first embodiment of the present invention, equipment with 10 temperature zones is used for the first reflow soldering.

Further, after performing the second reflow soldering on the substrate 11 , a step is further included: applying a sealant layer on the surface of the chip 15 to package the chip 15 .

Optionally, the material of the sealant layer can be, but not limited to, silica gel, epoxy glue and the like.

It can be understood that the design of spot-coating the sealant layer on the surface of the chip 15 can realize the function of protecting the chip 15 and realize the function of different light emission adjustment of the chip 15 . Specifically, in the embodiment of the present invention, the sealant layer is made of epoxy glue. With this design, since the epoxy glue has better ductility after curing, the chip 15 can be better protected.

Further, the surface of the chip 15 in contact with the soldering area 12 is provided with a tin-plated layer, and the thickness of the tin-plated layer is 6-18 μm. Preferably, the thickness of the tin plating layer is 8-15 μm.

Optionally, the thickness of the tin plating layer may be, but not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm.

Understandably, through the design of the tin-plated layer on the side of the chip 15 in contact with the soldering area 12, because the soldering area 12 will be partially recessed, there will be a bump after printing the solder paste 13, but this bump The height of the chip 15 may be lower than the concave plane of the welding area 12, so a tin-plated layer is provided on the side of the chip 15 in contact with the welding area 12, which can better weld the chip 15 on the welding area 12, that is, it can reduce the size of the chip. 15 The possibility of virtual soldering occurs, thereby further improving the yield of the product. In addition, when the tin-plated layer of the chip 15 is bonded to the welding area 12, there is a certain extrusion between the tin-plated layer of the chip 15 and the welding area 12, so that after the second reflow soldering, the chip 15 and the welding area Between 12 can be more solid. In addition, when the chip 15 is soldered to the welding area 12, there will be a relative angular shift between the two. After the chip 15 is lit, the chip 15 with the angular shift will emit uneven light, which will affect the overall luminous effect. Therefore, by setting the chip 15 and the design of the tin-plated layer on the welding area 12, the possibility of tilting the chip 15 can also be prevented, that is, the chip 15 can be arranged and relatively welded to the welding area 12 according to the preset posture. , so as to ensure that after the second reflow soldering, the chips 15 soldered to the substrate 11 can be uniformly arranged according to a preset state.

Further, the flux 14 includes one or more of rosin, tackifier, brightener, and organic solvent. In the flux 14, the content of rosin is 55% to 85%, and the tackifier The content of the brightener is 1% to 6%, the content of the brightener is 8% to 17%, and the content of the organic solvent is 8% to 17%.

As a preferred scheme of the first embodiment of the present invention, the content of rosin is 60% to 80%, the content of tackifier is 2% to 5%, the content of brightener is 10% to 15%, and the content of organic solvent 10% to 15%.

It can be understood that, through this design, this flux 14 can exhibit good tin speed, good soldering effect and cleaning effect during the soldering process. After the soldering work, there are more rosin residues on the surface of the substrate 11. The cleaning agent cleaning ensures that the cleaning surface has good insulation resistance, and the tackifier can greatly increase the viscosity of the welding zone 12, and the brightening agent can significantly improve the brightness and bonding force of the coating on the welding zone 12, which can greatly improve The stability of the welding area 12, and the organic solvent can be cleaned with water after the welding work is completed, which not only reduces the production cost of the customer, but also meets the environmental protection requirements. Therefore, by applying the above-mentioned soldering flux 14 to the welding area 12, the first is to clean the surface of the welding area 12, which facilitates the subsequent mounting of the chip 15; the second is to achieve the effect of wetting the welding area 12; It can speed up the efficiency of welding and further improve the efficiency of the overall process flow.

Further, before performing the second reflow soldering on the substrate 11 , a step is further included: performing automatic optical inspection on the substrate 11 after the chip 15 has been bonded.

Specifically, in the embodiment of the present invention, AOI (Automatic Optic Inspection, automatic optical inspection) is used to inspect and confirm the substrate 11 of the die-bonded chip 15 . AOI scans through optical methods, reads the images of chips 15 and solder feet through cameras, and detects solder paste 13, solder joints and chips 15 through logic algorithms or image comparison methods, so as to find out whether there are chip 15 offsets, chips 15 Defects such as missing assembly and welding short circuit, etc., and the defects can be marked through the display or automatic signs for maintenance personnel to repair.

It can be understood that, through the design of performing AOI inspection on the substrate 11 before performing the second reflow soldering on the substrate 11 , it is possible to ensure whether there are missing chips 15 , thereby further improving the yield rate of the product.

Further, after dispensing the solder flux 14 on the soldering area 12 of the substrate 11 after the first reflow soldering, a step is further included: performing SPI detection on the solder paste 13 which is dispensed with the flux 14 .

It can be understood that, through the design of SPI detection on the solder paste 13 coated with flux 14, it is possible to detect the consistency of the printed area, height, shape, XY offset, bridging and volume of the solder paste 13, so as to control The printing quality of the solder paste 13 further improves the precision of the subsequent soldering of the chip 15 . It is also understandable that the range of the above-mentioned detection index can be set according to the quality requirements of the product, which is not limited in this embodiment of the present invention.

In addition, please continue to refer to FIG. 2 , alignment points 16 are also provided on the substrate 11 in the embodiment of the present invention.

It can be understood that with this design, some positional deviations may occur during the process of the substrate 11 and the device (such as performing the second reflow soldering or die bonding), once the bonding between the substrate 11 and the device produces a position deviation, then after the second reflow soldering or after the crystal bonding, all the chips 15 may be soldered or bonded to the wrong position of the substrate 11, resulting in the chip 15 not being able to emit light normally, even if it can emit light normally, the effect of the light is not good. will be greatly affected. Therefore, by setting the alignment point 16 at the corresponding position of the substrate 11, all the chips 15 on the substrate 11 can be attached to the soldering area 12 at the correct position, thereby further ensuring the yield rate of the product. It can be seen that the above-mentioned design effectively improves the reliability of the placement method 1, that is, the products made by the placement method 1 have better luminous effect.

Please refer to FIG. 7 , the second embodiment of the present invention provides a light-emitting board 2 , and the light-emitting board 2 is made by the mounting method 1 of the first embodiment of the present invention.

Specifically, the light-emitting panel 2 includes a substrate 21 and a chip 22 disposed on the substrate 21 . It can be understood that the light-emitting panel 2 of the second embodiment of the present invention has the same beneficial effect as that of the mounting method 1 of the first embodiment of the present invention, which will not be repeated here.

Compared with the prior art, a mounting method using scrap substrates provided by the present invention has the following advantages:

1. In the mounting method provided by the embodiment of the present invention, the solder paste in the welding area can be melted by performing the first reflow soldering on the substrate, and then spot-coating flux on the welding area can make the subsequent chip soldering better On the welding area, the chip is finally solidified on the welding area through the crystal bonding technology, thereby completing the chip mounting process. It can be seen that the mounting method provided by the first embodiment of the present invention solves the technical problem that the chip cannot be mounted on the scrapped substrate due to solder paste printed on the soldering area, that is, the mounting method of the present invention can Therefore, the substrate can still realize the function of mounting chips, which can save costs and improve the yield rate of products.

2. The placement method provided by the embodiment of the present invention, through the design of the second reflow soldering on the substrate, after using the solder paste to connect the chip to the welding area, the solder paste is melted by controlling the heating temperature to achieve permanent Bonding, that is, soldering the chip on the pad.

3. The placement method provided by the embodiment of the present invention, through the design of setting the tin-plated layer on the chip and the welding area, firstly, the chip can be better welded on the welding area, that is, the chip can be reduced. The possibility of welding, thus further improving the yield of the product. The second is that when the tin-plated layer of the chip is bonded to the soldering area, there is a certain amount of extrusion between the tin-plated layer of the chip and the soldering area, so that after the second reflow soldering, the chip and the soldering area can be more firmly bonded. . The third is that when the chip is soldered to the welding area, there will be a relative angle offset between the two. After the chip is lit, the chip with the angle offset will emit uneven light and affect the overall luminous effect. It can prevent the possibility of chip tilting, that is, the chips can be arranged and soldered to the welding area according to the preset posture, so as to ensure that after the second reflow soldering, the chips soldered to the substrate can follow the preset state Uniform arrangement.

4. The placement method provided by the embodiment of the present invention, through this design, this flux can show good tin speed, good welding effect and cleaning effect in the welding process, and after welding, the surface of the substrate is relatively weak. More rosin residues can be cleaned with an appropriate cleaning agent to ensure good insulation resistance on the cleaned surface, and the tackifier can greatly increase the viscosity of the welding area, and the brightener can significantly improve the brightness and bonding of the coating in the welding area The strength can greatly improve the stability of the welding area, and the organic solvent can be cleaned with water after the welding work is completed, which not only reduces the production cost of the customer, but also meets the requirements of environmental protection. Therefore, by applying the above-mentioned soldering flux 14 to the soldering area, the first is to clean the surface of the soldering area, which is convenient for subsequent mounting of the chip, the second is to wet the soldering area, and the third is to speed up the welding process. The efficiency can further improve the efficiency of the overall process flow.

5. The placement method provided by the embodiment of the present invention can ensure whether there are missing chips through the design of AOI detection on the substrate before the second reflow soldering of the substrate, thereby further improving the yield of the product.

6. The placement method provided by the embodiments of the present invention can detect the printing area, height, shape, XY offset, bridging and volume of the solder paste printing by designing the SPI detection of the solder paste coated with flux. Consistency, so as to control the quality of solder paste printing and improve the accuracy of subsequent chip soldering.

7. The mounting method provided by the embodiment of the present invention, through the design of spot-coating sealant layer on the surface of the chip, can realize the function of protecting the chip, and can realize the function of different light emission adjustment of the chip.

8. The luminescent panel provided by the embodiment of the present invention has the same beneficial effects as the mounting method of the present invention, which will not be repeated here.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements within the principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A chip mounting method utilizing scrap substrate, is characterized in that: said chip mounting method comprises the following steps: Provide scrap substrates and chips, where there is solder paste in the soldering area of the substrate; Carrying out the first reflow soldering to the substrate to melt the solder paste in the soldering area; Spot-coat flux on the welding area of the substrate after the first reflow soldering; Die-bonding the chip to the soldering area where the flux has been applied. 2. The mounting method according to claim 1, characterized in that: after the chip is solidified to the welding area after the flux is applied, it also includes the step of: performing a second reflow soldering on the substrate to The chip is welded on the welding area. 3 . The mounting method according to claim 2 , wherein a tin-plated layer is provided on the surface of the chip in contact with the soldering area, and the thickness of the tin-plated layer is 6-18 μm. 4 . 4. The mounting method according to claim 1, characterized in that: the flux includes one or more of rosin, tackifier, brightener, organic solvent, in the flux, the mass In percentage terms, the content of the rosin is 55% to 85%, the content of the tackifier is 1% to 6%, the content of the brightener is 8% to 17%, and the content of the organic solvent is 8% to 17%. 5 . The mounting method according to claim 2 , characterized in that: before performing the second reflow soldering on the substrate, it further comprises a step of optically inspecting the substrate on which the chips have been bonded. 6 . 6. The mounting method according to claim 1, characterized in that: before performing the first reflow soldering on the substrate, it further comprises the step of: spot-coating solder paste with a melting point of 130-180°C on the soldering area superior. 7. The mounting method according to claim 2, characterized in that: before performing the second reflow soldering on the substrate, it further comprises the step of: spot-coating solder paste with a melting point of 130-180°C until the spot-coating is helpful. flux on the soldering area. 8. mounting method as claimed in claim 6 is characterized in that: after carrying out spot-coating flux to the soldering area of the substrate after the first reflow soldering, also comprises the step; Solder paste for SPI inspection. 9. The mounting method according to claim 2, characterized in that: after performing the second reflow soldering on the substrate, further comprising the step of: applying a sealant layer on the surface of the chip. 10. A light-emitting board, characterized in that: the light-emitting board is made by the mounting method according to any one of claims 1-9.

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