Substrate with micro-pitch conductive bumps and method for manufacturing the same

Abstract

A method for manufacturing a substrate with micro-pitch conductive bumps, comprising the steps of: providing a base pad on a circuit substrate, the circuit substrate including a first connection pad and a second connection pad, and the base pad being provided on the first connection pad; providing a printing stencil on the circuit substrate, the printing stencil being provided with a printing hole therethrough, and the printing hole corresponding to the base pad; providing a first solder in the printing hole, the first solder being solder paste, melting and solidifying the first solder to form a first solder body, and the first solder body connecting the base pad; removing the printing stencil; providing a second solder on the second connection pad, the second solder being a solder ball, melting and solidifying the second solder to form a second solder body, and flattening the first solder body and the second solder body to make them flush to obtain a substrate. Wherein, the first solder body and the base pad form a first conductive bump, the second solder body forms a second conductive bump, and the distance between the first conductive bump and the second conductive bump is less than 90 microns. Additionally, the present application also provides a substrate with micro-pitch conductive bumps.

Description

Technical Field

[0001] This application relates to the field of manufacturing electronic products, and particularly to a substrate with micro-pitch conductive bumps and a manufacturing method thereof. Background Art

[0002] In modern electronic products, the connection between the substrate and the semiconductor component is welded through conductive bumps. With the progress of technology, the number of conductive bumps arranged is increasing continuously, the wiring structure becomes more and more dense, and the distance between conductive bumps is getting smaller and smaller.

[0003] Traditional conductive bumps are mainly formed by the following two methods: One is screen printing solder paste. That is, using screen printing technology to accurately print the solder paste onto the predetermined position on the substrate to form conductive bumps. However, the reduction of the conductive bump pitch not only increases the difficulty of processing using screen printing solder paste, but also may cause solder bridging, resulting in electrical abnormalities, such as open circuit or short circuit. The other is secondary image transfer. That is, through chemical or electroplating metal methods, electroplated conductive bumps are formed. However, this method requires complex processes such as multiple alignments, adding solder mask layers, electroless plating of metal, and electroplating of metal. In addition, the solder mask layer and part of the exposed electroless plating layer need to be removed in subsequent processes. This method is also easily affected by the electroplating uniformity, resulting in inconsistent heights of the conductive bumps. Summary of the Invention

[0004] In view of this, it is necessary to provide a manufacturing method for micro-pitch conductive bumps to solve the above problems.

[0005] In addition, this application also provides a connection substrate manufactured according to the above manufacturing method for micro-pitch conductive bumps.

[0006] A method for manufacturing a substrate with micro-pitch conductive bumps, comprising the steps of: providing a base pad on a circuit substrate, the circuit substrate including a first connection pad and a second connection pad, the base pad being provided on the first connection pad; providing a printing stencil on the circuit substrate, the printing stencil being provided with printing holes therethrough, the printing holes corresponding to the base pad; providing a first solder in the printing holes, the first solder connecting the base pad; removing the printing stencil; providing a second solder on the second connection pad, and flattening the first solder and the second solder so that the first solder and the second solder are flush, thereby obtaining the substrate, wherein the first solder and the base pad form a first conductive bump, the second solder forms a second conductive bump, and the distance between the first conductive bump and the second conductive bump is less than 90 micrometers. The first solder is solder paste, the second solder is solder ball, and the method for manufacturing the substrate further comprises the steps of: melting and solidifying the first solder to form a first solder body, melting and solidifying the second solder to form a second solder body, and flattening the first solder body and the second solder body so that the first solder body and the second solder body are flush.

[0007] In some possible embodiments, the step of "providing a base pad on a circuit substrate" includes: providing a first solder resist layer on one side of the substrate, the first solder resist layer covering the first connection pad and the second connection pad; exposing and developing the first solder resist layer to form a first solder resist layer, the first solder resist layer being formed with a first opening therethrough, the first connection pad being exposed at the bottom of the first opening; electroplating to form the base pad in the first opening.

[0008] In some possible embodiments, the first conductive bump further includes a first treatment layer located between the first solder and the base pad, the second conductive bump further includes a second treatment layer located between the second solder and the second connection pad. Before the step of "providing a printing stencil on the circuit substrate", it further includes: providing a first treatment layer on the base pad and providing a second treatment layer on the second connection pad, the first treatment layer and the second treatment layer being flush with the first solder resist layer respectively. The step of "providing a first solder in the printing holes" includes: providing the first solder on the first treatment layer, wherein the first solder, the base pad and the first treatment layer form the first conductive bump. The step of "providing a second solder on the second connection pad" includes: providing the second solder on the second treatment layer, wherein the second solder and the second treatment layer form the second conductive bump.

[0009] In some possible embodiments, both the first treatment layer and the second treatment layer are formed by chemical deposition or electroplating.

[0010] In some possible implementations, the circuit substrate includes a third connection pad, a conductive body, and an insulator, the first connection pad and the second connection pad are exposed on one side of the insulator, the third connection pad is exposed on the other side of the insulator, the conductive body connects the first connection pad and the third connection pad, and the step of "forming the base pad by electroplating in the first opening" includes: setting a seed layer on the third connection pad. Connecting the seed layer and a plating cathode, immersing the first connection pad in a plating solution, and reducing the metal ions in the plating solution to a metal element on the first connection pad to form the base pad. After the step of "setting the base pad on the circuit substrate", it also includes: removing the seed layer.

[0011] In some possible implementations, the step of "arranging a seed layer on the third connection pad" includes: arranging a second solder resist layer on the other side of the insulator, exposing and developing the second solder resist layer to form a second solder resist layer, the second solder resist layer having a second opening formed therethrough, and the third connection pad is exposed in the second opening. The seed layer is arranged on the second solder resist layer, and a portion of the seed layer is filled into the second opening to connect to the third connection pad.

[0012] In some possible implementations, the step of “disposing a seed layer on the third connection pad” includes: disposing the seed layer on the third connection pad by sputtering or chemical deposition.

[0013] In some possible implementations, the second solder is a solder ball, and the step of “arranging the second solder on the second connection pad” includes: implanting the solder ball mechanically or manually.

[0014] A substrate with micro-pitch conductive bumps, comprising a circuit substrate, a first conductive bump and a second conductive bump. The substrate comprises a first connection pad and a second connection pad electrically insulated from the first connection pad. The first conductive bump is arranged on one side of the circuit substrate, the first conductive bump comprises a base pad and a first solder body, the first connection pad is connected to the circuit substrate, and the base pad is connected between the first solder body and the first connection pad. The second conductive bump is arranged on one side of the circuit substrate, the distance between the first conductive bump and the second conductive bump is less than 90 microns, the second conductive bump comprises a second solder body, and the second connection pad is connected to the circuit substrate.

[0015] In some possible embodiments, the circuit substrate further includes an insulator and a conductor buried in the insulator, the first connection pad is exposed on one side of the insulator, one end of the conductor is connected to the first connection pad, the second connection pad is exposed on the other side of the insulator, and the other end of the conductor is connected to the second connection pad.

[0016] Compared with the prior art, the manufacturing method of the substrate with micro-pitch conductive bumps provided by the present application sets the first solder body on the first processing layer by using printing technology, and sets the second solder body on the second processing layer by using the ball mounting technology. On the premise that the total number of the first solder body and the second solder body remains unchanged, compared with forming all the first solder bodies and the second solder bodies only by using printing technology, the combined use of printing technology and ball mounting technology can reduce the hole density of the printing stencil used in the printing technology, thereby helping to improve the quality of the first solder body obtained by printing and reducing bridging short circuits. In addition, since a base pad is provided on the first connection pad before the first processing layer is set, the base pad can help reduce the height of the first solder body, thereby reducing the amount of solder used, and thus the steel plate opening can be reduced, and the concern about the inability to open the loop due to too close spacing can be eliminated. Furthermore, since the solder is printed into the first opening of the first solder resist layer in a stuffing manner, the height difference of the first solder can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a cross-sectional schematic view of a circuit board provided by an embodiment of the present application.

[0018] Figure 2 is Figure 1 a cross-sectional schematic view of the circuit board shown after the first solder resist layer and the second solder resist layer are provided.

[0019] Figure 3 is Figure 2 a cross-sectional schematic view of the second solder resist layer shown after a seed layer is provided.

[0020] Figure 4 is Figure 3 a cross-sectional schematic view of the first solder resist layer shown after a base pad is provided therein.

[0021] Figure 5 is Figure 4 a cross-sectional schematic view of the circuit board shown after the base pad is provided with the first processing layer.

[0022] Figure 6 is Figure 5 a cross-sectional schematic view of the first processing layer shown after the first solder is provided.

[0023] Figure 7 is Figure 6 a cross-sectional schematic view of the second connection pad shown after the second solder is provided.

[0024] Figure 8 FIG. is a cross-sectional schematic view of a substrate with micro-pitch conductive bumps provided by an embodiment of the present application.

[0025] MAIN ELEMENT SYMBOL DESCRIPTION

[0026] Circuit board 10

[0027] Insulator 11

[0028] First connection pad 12

[0029] Second connection pad 13

[0030] Third connection pad 14

[0031] Conductor 15

[0032] Resin 151

[0033] Core board 16

[0034] First side plate 17

[0035] Second side plate 18

[0036] First insulator 111

[0037] Second insulator 112

[0038] Third insulator 113

[0039] First circuit layer 171

[0040] Second circuit layer 181

[0041] First solder resist layer 20

[0042] Second solder resist layer 21

[0043] First opening 201

[0044] Second opening 211

[0045] Seed layer 23

[0046] Base pad 24

[0047] First groove 241

[0048] First treatment layer 30

[0049] Second treatment layer 31

[0050] Second groove 311

[0051] Third treatment layer 32

[0052] Third groove 321

[0053] Printing stencil 33

[0054] Printing hole 331

[0055] First solder 40

[0056] Second solder 41

[0057] The first solder body 401

[0058] The second solder body 411

[0059] The first conductive bump 101

[0060] The second conductive bump 102

[0061] The substrate 100

[0062] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Specific embodiments

[0063] Next, the technical solutions in the embodiments of the present application will be described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0064] It should be noted that when a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time.

[0065] Please refer to Figures 1 to 8 , an embodiment of the present application provides a method for manufacturing a substrate 100 with micro-pitch conductive bumps, including the steps of:

[0066] S1: Please refer to Figure 1 , provide a circuit substrate 10, the circuit substrate 10 includes an insulator 11, a first connection pad 12, a second connection pad 13, a third connection pad 14, and a conduction body 15. The first connection pad 12 and the second connection pad 13 are spaced apart on one side of the insulator 11. The third connection pad 14 is disposed on the other side of the insulator 11. The conduction body 15 is disposed inside the insulator 11, and one end of the conduction body 15 is connected to the first connection pad 12 and the other end is connected to the third connection pad 14. Wherein, the conduction body 15 is a hollow conduction body, and the inside of the conduction body 15 is filled with resin 151.

[0067] In this embodiment, the circuit board 10 includes a core board 16, a first side plate 17, and a second side plate 18. The first side plate 17 and the second side plate 18 are respectively disposed on opposite side surfaces of the core board 16. The insulator 11 includes a first insulator 111, a second insulator 112, and a third insulator 113. The first side plate 17 includes the first insulator 111, a first circuit layer 171, the first connection pad 12, and the second connection pad 13. The core board 16 includes the third insulator 113 and the conduction body 15. The second side plate 18 includes the second insulator 112, a second circuit layer 181, and the third connection pad 14. The first insulator 111 and the second insulator 112 are respectively disposed on opposite sides of the third insulator 113.

[0068] The first circuit layer 171 is disposed within the first insulator 111. The first connection pad 12 and the second connection pad 13 are connected to the first circuit layer 171, and both the first connection pad 12 and the second connection pad 13 are exposed on a side of the first insulator 111 facing away from the third insulator 113. The first connection pad 12 is connected to one end of the conduction body 15.

[0069] The second circuit layer 181 is disposed within the second insulator 112. The third connection pad 14 is connected to the second circuit layer 181, and the third connection pad 14 is exposed on a side of the second insulator 112 facing away from the third insulator 113. The third connection pad 14 is connected to the other end of the conduction body 15.

[0070] In this embodiment, the first connection pad 12, the second connection pad 13, and the third connection pad 14 are all formed by multi-layer stacked electroplating. The number of the first connection pads 12 is two, the number of the second connection pads 13 is one, the number of the third connection pads 14 is three, and the number of the conduction bodies 15 is two. Each of the first connection pads 12 is connected to one of the third connection pads 14 through one of the conduction bodies 15. The second connection pad 13 is not connected to the third connection pad 14 through the conduction body 15. In other embodiments of the present application, the number of the first connection pads 12 may be three or more, the number of the second connection pads 13 may be two or more, the number of the third connection pads 14 may be four or more, and the number of the conduction bodies 15 may be three or more. The present application does not limit the numbers of the first connection pad 12, the second connection pad 13, the third connection pad 14, and the conduction body 15.

[0071] S2: Please refer to Figure 2A first solder resist layer 20 and a second solder resist layer 21 are respectively disposed on both sides of the circuit substrate 10. The first solder resist layer 20 has a first opening 201, and the first connection pad 12 and the second connection pad 13 are both exposed at the bottom of the first opening 201. The second solder resist layer 21 has a second opening 211, and the third connection pad 14 is exposed at the bottom of the second opening 211.

[0072] In this embodiment, step S2 specifically includes:

[0073] S21: Form the first solder resist layer 20 and the second solder resist layer 21 by coating, printing and image transfer. The first solder resist layer 20 and the second solder resist layer 21 can be used to prevent solder from diffusing in unwanted areas and ensure that solder is formed only at desired locations.

[0074] S3: See Figure 3 A seed layer 23 is disposed on the second solder resist layer 21. A portion of the seed layer 23 fills the second opening 211 and connects to the third connection pad 14. Specifically, the seed layer 23 is formed on the second solder resist layer 21 by sputtering or chemical deposition.

[0075] S4: See Figure 4 A base pad 24 is disposed on the first connection pad 12 exposed in the first opening 201. The thickness of the base pad 24 is smaller than the depth of the first opening 201, so that the first opening 201 cannot be filled by the base pad 24, thereby forming a first groove 241.

[0076] In this embodiment, step S4 specifically includes:

[0077] S41: Connecting the seed layer 23 and the electroplating cathode (not shown). The seed layer 23 is electrically connected to the third connection pad 14, and the third connection pad 14 is electrically connected to the first connection pad 12 through the conductive body 15. It can be understood that the third connection pad 14 is not connected to the second connection pad 13, so the seed layer 23 is not electrically connected to the second connection pad 13.

[0078] S42: Put the first connection pad 12 and the second connection pad 13 into the electroplating solution together, so that the metal ions in the electroplating solution are reduced to metal elements on the first connection pad 12 and deposited to form the base pad 24. It can be understood that the electroplating cathode is not connected to the second connection pad 13, so the base pad 24 cannot be formed on the second connection pad 13.

[0079] S43: removing the seed layer 23.

[0080] S5: See Figure 5, a first treatment layer 30 is disposed on the base pad 24, and a second treatment layer 31 is disposed on the second connection pad 13. Specifically, the first treatment layer 30 is disposed in the first groove 241, and the outer surface of the first treatment layer 30 is flush with the outer surface of the first solder resist layer 20. The thickness of the second treatment layer 31 is less than the depth of the first opening 201, so that the first opening 201 cannot be filled by the second treatment layer 31, thereby forming a second groove 311. Among them, the material of the first treatment layer 30 and the second treatment layer 31 is nickel, palladium, gold, tin or alloys thereof, and the first treatment layer 30 and the second treatment layer 31 can be used to provide a good welding foundation at the same time, so that the subsequent solder can be evenly and firmly attached.

[0081] In this embodiment, step S5 further includes:

[0082] S51: a third processing layer 32 is provided on the third connection pad 14, wherein the thickness of the third processing layer 32 is less than the depth of the second opening 211, thereby forming a third groove 321. The third processing layer 32 is made of the same material as the first processing layer 30, and can be used to prevent the solder from diffusing in unnecessary areas, ensuring that the solder is formed only at the required position, and can also be used to protect the third connection pad 14 from being affected by heat or chemicals, etc. The third groove 321 can be used for soldering when connecting other electronic components.

[0083] S6: See Figure 6 , a printing screen 33 is arranged on the first solder resist layer 20. The printing screen 33 is provided with printing holes 331, and the printing holes 331 are arranged corresponding to the base pad 24. The printing screen 33 covers the second groove 311; then the first solder 40 is scraped into the printing hole 331 on one side of the printing hole 331 by a scraper, and the first solder 40 is connected to the base pad 24.

[0084] S7: See Figure 7 , remove the printed stencil 33, and implant the second solder 41 in the second groove 311, the second solder 41 is connected to the second connection pad 13. Specifically, the second solder 41 is a solder ball, which is implanted into the second groove 311 manually or mechanically and connected to the second connection pad 13.

[0085] S8: See Figure 8, melting and solidifying the first solder 40 to form a first solder body 401, melting and solidifying the second solder 41 to form a second solder body 411, and flattening the first solder body 401 and the second solder body 411 so that the first solder body 401 and the second solder body 411 are flush, thereby obtaining the substrate 100. Wherein, the first solder body 401, the base pad 24, and the first treatment layer 30 form a first conductive bump 101. The second solder body 411 and the second treatment layer 31 form the second conductive bump 102. The distance between the first conductive bump 101 and the second conductive bump 102 is less than 90 micrometers. It can be understood that, in other embodiments of the present application, step S8 can also be omitted.

[0086] Compared with the prior art, the substrate manufacturing method of the micro-pitch conductive bump provided by the present application has the following advantages:

[0087] (1) By using a printing technique to dispose the first solder body 401 on the first treatment layer 30, and by using a ball mounting technique to dispose the second solder body 411 on the second treatment layer 31. On the premise that the total number of the first solder body 401 and the second solder body 411 remains unchanged, compared with forming all the first solder body 401 and the second solder body 411 only by using the printing technique, the combined use of the printing technique and the ball mounting technique can reduce the hole density of the printing stencil used in the printing technique, thereby helping to improve the quality of the first solder body 401 obtained by printing and reducing bridging short circuits. In addition, since the base pad 24 is disposed on the first connection pad 12 before the first treatment layer 30 is disposed, the base pad 24 can help reduce the height of the first solder body 401, thereby reducing the amount of solder used, and thus the steel plate open loop can be reduced, and the concern about the inability to open the loop due to too close spacing can be eliminated. Furthermore, since the solder is printed into the first opening of the first solder resist layer in a stuffing manner, the height difference of the first solder can be improved.

[0088] (2) By electrically connecting the first connection pad 12 to the third connection pad 14 on the opposite side of the circuit substrate 10, then connecting a seed layer 23 on the third connection pad 14, and then connecting the seed layer 23 to the electroplating cathode, during the electroplating process, the base pad 24 can be deposited and formed on the first connection pad 12, so that there is no need to perform multiple image transfer processes on the side of the circuit substrate 10 where the first connection pad 12 is disposed to prepare the base pad 24, which is beneficial to simplifying the process and improving production efficiency.

[0089] Also, please refer to Figure 8, an embodiment of the present application further provides a substrate 100 for micro-pitch conductive bumps. The substrate 100 includes a circuit substrate 10, a first conductive bump 101, and a second conductive bump 102. The first conductive bump 101 is disposed on one side of the circuit substrate 10. The first conductive bump 101 includes a base pad 24, a first treatment layer 30, and a first solder body 401. The first connection pad 12 is connected to the first conductive bump 101, and the base pad 24 is connected between the first solder body 401 and the first connection pad 12. The second conductive bump 102 is disposed on the other side of the circuit substrate 10. The distance between the first conductive bump 101 and the second conductive bump 102 is less than 90 micrometers. The second conductive bump 102 includes a second solder body 411 and the second treatment layer 31. The second connection pad 13 is connected between the circuit substrate 10 and the second solder body 411. Wherein, the first solder body 401 and the second solder body 411 can be used to connect a chip, and the third groove 321 can be used to implant solder balls, and the solder balls can be used to connect electronic components (such as, a flexible board, another chip).

[0090] Those of ordinary skill in the art of the present technology should recognize that the above embodiments are only used to illustrate the present application, rather than to limit the present application. As long as within the spirit and scope of the present application, appropriate changes and variations made to the above embodiments fall within the scope of the disclosure of the present application.

Claims

1. A method for manufacturing a substrate with micro-pitch conductive bumps, It is characterized in that Includes steps: A base pad is arranged on a circuit substrate, wherein the circuit substrate comprises a first connection pad, a second connection pad, a third connection pad, a conductive body and an insulator, wherein the first connection pad and the second connection pad are exposed on one side of the insulator, and the third connection pad is exposed on the other side of the insulator, the conductive body connects the first connection pad and the third connection pad, and the base pad is arranged on the first connection pad; A first solder resist layer is provided on one side of the substrate, the first solder resist layer covers the first connection pad and the second connection pad; the first solder resist layer is exposed and developed to form a first solder resist layer, a first opening is formed through the first solder resist layer, the first connection pad is exposed at the bottom of the first opening, and the thickness of the base pad is less than the depth of the first opening, thereby forming a first groove; The step of "arranging a base pad on the circuit substrate" includes: arranging a seed layer on the third connection pad; connecting the seed layer and a plating cathode, immersing the first connection pad in a plating solution, and reducing the metal ions in the plating solution to a metal element on the first connection pad to form the base pad; after the step of "arranging a base pad on the circuit substrate", it also includes: removing the seed layer; A first processing layer is disposed on the base pad, and a second processing layer is disposed on the second connection pad, wherein the first processing layer is flush with the first solder resist layer, and the thickness of the second processing layer is less than the depth of the first opening, thereby forming a second groove; A printing screen is arranged on the circuit substrate, wherein the printing screen is provided with printing holes, and the printing holes are arranged corresponding to the base pad; Disposing a first solder in the printing hole, wherein the first solder is connected to the base pad, comprising: disposing a first solder in the first groove, wherein the first solder is connected to the first processing layer; removing the printing screen; Disposing a second solder on the second connection pad includes: disposing a second solder in the second groove, the second solder connecting the second processing layer, and The first solder and the second solder are flattened so that the first solder and the second solder are flush with each other to obtain the substrate, wherein The first solder, the base pad and the first processing layer form a first conductive bump, the second solder and the second processing layer form a second conductive bump, and the distance between the first conductive bump and the second conductive bump is less than 90 micrometers; The first solder is solder paste, the second solder is solder balls, and the substrate manufacturing method further comprises the steps of: melting and solidifying the first solder to form a first solder body, melting and solidifying the second solder to form a second solder body, The first weld body and the second weld body are flattened so that the first weld body and the second weld body are flush.

2. The manufacturing method according to claim 1, It is characterized in that The first treatment layer and the second treatment layer are both formed by chemical deposition or electroplating.

3. The manufacturing method according to claim 1, It is characterized in that The step of "arranging a seed layer on the third connection pad" includes: A second solder resist layer is provided on the other side of the insulator, Expose and develop the second solder resist layer to form the second solder resist layer, a second opening is formed through the second solder resist layer, and the third connection pad is exposed in the second opening; Provide the seed layer on the second solder resist layer, and part of the seed layer is filled into the second opening to connect the third connection pad.

4. The manufacturing method according to claim 3, wherein, the step of "providing a seed layer on the third connection pad" includes: providing the seed layer on the third connection pad by sputtering or chemical deposition.

5. The manufacturing method according to claim 1, wherein, the second solder is a solder ball, and the step of "providing the second solder on the second connection pad" includes: implanting the solder ball by mechanical or manual means.

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