Circuit board and manufacturing method thereof

Abstract

This application discloses a circuit board and its manufacturing method. The circuit board includes a circuit substrate, a plurality of conductive pillars, a plurality of solder pastes, and electronic components. The circuit substrate includes a first substrate, which includes a first substrate layer and a first conductor layer and a second conductor layer disposed on two opposing surfaces of the first substrate layer. The first conductor layer includes a plurality of connector pads, and the second conductor layer has an opening exposing the first substrate layer. The first substrate layer has a plurality of through holes exposed in the opening. The plurality of conductive pillars are accommodated in the opening and pass through the plurality of through holes to connect with the plurality of connector pads. The conductive pillars are disposed separately from the second conductor layer, and the surface of the conductive pillars facing away from the connector pads has a groove. Solder paste is accommodated in the groove. The electronic components include solder balls, which cover the surface of the conductive pillars facing away from the connector pads and are in contact with the solder paste.

Description

[Technical Field]

[0001] This application relates to the field of circuit board technology, and in particular to a circuit board and a method for manufacturing the same. [Previous Technology]

[0002] With the rapid development of technology, high-density miniaturization has become a major trend in electronic products, resulting in increasingly smaller spacing between solder pads on circuit boards used to mount various electronic components. In the prior art, when electronic components are soldered onto circuit boards, insufficient solder strength can easily lead to poor soldering. [Summary of the Invention]

[0003] In view of this, it is necessary to provide a circuit board that can solve the above problems and a method for manufacturing the same.

[0004] A first aspect of this application provides a circuit board, including a circuit substrate, a plurality of conductive pillars, a plurality of solder pastes, and electronic components. The circuit substrate includes a first substrate, which includes a first substrate layer and a first conductor layer and a second conductor layer disposed on two opposing surfaces of the first substrate layer. The first conductor layer includes a plurality of connector pads. The second conductor layer has an opening exposing the first substrate layer. The first substrate layer has a plurality of through-holes exposed in the opening. The plurality of connector pads are respectively exposed in the plurality of through-holes. The plurality of conductive pillars are received in the opening and pass through the plurality of through-holes to contact the plurality of connector pads. The conductive pillars are disposed separately from the second conductor layer, and the surface of the conductive pillar facing away from the connector pads has a groove. The solder paste is received in the groove. The electronic components include solder balls, which cover the surface of the conductive pillar facing away from the connector pads and are in contact with the solder paste.

[0005] A second aspect of this application provides a method for manufacturing a circuit board, comprising the following steps: providing a circuit substrate, the circuit substrate comprising a first substrate, the first substrate comprising a first substrate layer and a first conductor layer and a second conductor layer disposed on two opposing surfaces of the first substrate layer; forming a plurality of through holes on the first substrate, the through holes penetrating the second conductor layer and the first substrate layer, and exposing a portion of the first conductor layer; filling the through holes with a conductive material, the conductive material filling the plurality of through holes and covering the surface of the second conductor layer, the conductive material also being in contact with the first conductor layer; removing a portion of the conductive material to form a plurality of spaced conductive pillars, the plurality of conductive pillars respectively filling a plurality of fillers and connecting to the first conductor layer; removing a portion of the second conductor layer, so that the conductive pillars are disposed apart from the second conductor layer; forming a groove on the surface of the conductive pillars away from the first conductor layer; filling the groove with solder paste; and fabricating a plurality of connection pads on the first conductor layer, the plurality of connection pads corresponding to and connected to the plurality of conductive pillars one by one. Electronic components are mounted on a plurality of conductive pillars, each electronic component comprising a plurality of solder balls, each solder ball making contact with a plurality of solder pastes in a corresponding manner; the circuit board on which the electronic components are mounted is placed in a reflow oven and heated, causing the solder balls and solder pastes to melt and bond together.

[0006] In the circuit board and manufacturing method provided in the embodiments of this application, by configuring conductive pillars connected to the connecting pads, opening grooves on the conductive pillars, and filling the grooves with solder paste, electronic components are soldered by solder balls to the solder paste contained in the conductive pillars and the surface of the conductive pillars, thereby increasing the contact area between the solder and the conductive pillars, which is beneficial to improve the bonding force and thus improve the soldering strength.

Implementation Method

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0017] One embodiment of this application provides a method for manufacturing a circuit board, which includes the following steps.

[0018] Step S1, referring to FIG. 1, a circuit board 10 is provided. The circuit board 10 includes a first substrate 11. The first substrate 11 includes a first substrate layer 111 and a first conductor layer 112 and a second conductor layer 113 disposed on two opposite surfaces of the first substrate layer 111. In this embodiment, the first conductor layer 112 and the second conductor layer 113 are circuit layers formed by patterned copper layers. In another embodiment, the first conductor layer 112 and the second conductor layer 113 are a single piece of copper foil, and the first substrate 11 is a double-sided copper-clad laminate.

[0019] In some embodiments, the circuit board 10 further includes a second substrate 12, which is bonded to the surface of the second conductor layer 113 by an adhesive layer 13. The second substrate 12 includes a second substrate layer 121 and a third conductor layer 122 stacked together. The adhesive layer 13 is sandwiched and bonded between the second substrate layer 121 and the second conductor layer 113. In this embodiment, the third conductor layer 122 is a circuit layer formed by patterned copper layers. In another embodiment, the third conductor layer 122 is a single-sided copper-clad laminate of the entire second substrate 12. The circuit board 10 is provided with an opening 120 that penetrates the third conductor layer 122, the second substrate layer 121 and the adhesive layer 13, and the opening 120 exposes a portion of the second conductor layer 113.

[0020] The materials of the first substrate layer 111 and the second substrate layer 121 may each be, but are not limited to, prepreg (PP) containing glass fiber and epoxy resin, polyimide, polyethylene terephthalate, or polyethylene naphthalate. The materials of the first conductor layer 112, the second conductor layer 113, and the third conductor layer 122 may each be, but are not limited to, gold, silver, etc.

[0021] Step S2, referring to FIG2, a plurality of through holes 110 are formed on the first substrate 11. The through holes 110 penetrate the second conductor layer 113 and the first substrate layer 111, and expose a portion of the first conductor layer 112. The plurality of through holes 110 are exposed in the opening 120, and the sidewalls of the through holes 110 are misaligned with the sidewalls of the opening 120 to reduce the risk of interference between the first substrate 11 and the electronic components during subsequent mounting. The through holes 110 are formed by laser drilling or mechanical drilling processes.

[0022] Step S3, referring to FIG3, a filler 20 is formed in the through hole 110, and the filler 20 is supported on the first conductor layer 112. There is a gap between the sidewall of the filler 20 and the sidewall of the through hole 110, that is, the filler 20 contained in the through hole 110 does not contact the first substrate layer 111 and the second conductor layer 113. The side surface of the filler 20 is beveled to increase the contact area between the filler 20 and the subsequently formed conductive pillar. In this embodiment, the filler 20 is generally trapezoidal.

[0023] In this embodiment, the filler 20 is solder paste. After the solder paste is filled into the through-hole 110, the circuit board 10 is heated in a reflow oven to melt the solder paste, thereby improving the adhesion between the solder paste and the first conductor layer 112. In another embodiment, the filler 20 is an adhesive with good adhesion, which facilitates fixation to the first conductor layer 112. In another embodiment, the filler 20 is a solid refrigerant, such as a fluoride or a polymer, which helps to improve heat dissipation performance.

[0024] Step S4, referring to FIG4, is to fill the through hole 110 and opening 120 with conductive material 30. The conductive material 30 covers the plurality of fillers 20 and covers the surface of the second conductor layer 113 exposed in the opening 120. The conductive material 30 is also in contact with the plurality of connecting pads 112a. The conductive material 30 may be, but is not limited to, a metal, such as copper, silver, etc. In this embodiment, the conductive material 30 is copper. The conductive material 30 may be formed by an electroplating process.

[0025] Step S5, referring to FIG5, remove a portion of the conductive material to form a plurality of spaced conductive pillars 31. The plurality of conductive pillars 31 respectively cover a plurality of fillers 20 and are connected to the first conductor layer 112. The conductive pillars 31 are disposed separately from the sidewall of the opening 120. In this embodiment, the conductive material located outside the through hole 110 is removed by laser cutting along the sidewall of the through hole 110 to form a plurality of conductive pillars 31. That is, the portion of conductive material located inside the through hole 110 and aligned with the corresponding through hole 110 constitutes a conductive pillar 31.

[0026] In some embodiments, step S5 further includes: removing a portion of the second conductor layer 113, so that the conductive post 31 and the second conductor layer 113 are disposed separately. In some embodiments, the second conductor layer 113 exposed in the opening 120 is removed along the sidewall of the opening 120 by a laser cutting process.

[0027] Step S6, referring to FIG5, a groove 311 is formed on the surface of the conductive post 31 facing away from the first conductor layer 112. The groove 311 is disposed separately from the filler 20, that is, the groove 311 and the filler 20 are separated by a portion of the conductive post 31. The side surface of the groove 311 is beveled to increase the contact area between the conductive post 31 and the subsequently formed solder paste. In this embodiment, the groove 311 is generally inverted trapezoidal. The groove 311 is formed by laser drilling.

[0028] Step S7, referring to Figure 6, fill the groove 311 with solder paste 40. The solder paste 40 fills the groove 311 completely. The surface of the solder paste 40 away from the bottom wall of the groove 311 is lower than or flush with the surface of the conductive post 31 away from the first conductor layer 112, in order to reduce the risk of molten solder paste overflowing into the space between two adjacent conductive posts 31 during subsequent reflow soldering. In another embodiment, the surface of the solder paste 40 away from the bottom wall of the groove 311 is slightly lower than the conductive post 31. The solder paste 40 can be filled into the groove 311 by a spraying process.

[0029] Step S8, please refer to Figure 6, a plurality of connecting pads 112a are fabricated on the first conductor layer 112. A plurality of conductive pillars 31 are connected to the plurality of connecting pads 112a in a one-to-one correspondence. In this embodiment, a laser cutting process is used to fabricate the plurality of connecting pads 112a on the first conductor layer 112. Compared to etching, laser cutting has higher precision and can fabricate connecting pads 112a with smaller spacing, which is beneficial for the miniaturization of the circuit board.

[0030] Step S9, referring to Figure 7, involves mounting the electronic component 50 onto a plurality of conductive posts 31. The electronic component 50 includes a plurality of solder balls 51, each of which makes contact with a plurality of solder paste 40. The electronic component 50 is mounted onto the plurality of conductive posts 31 using surface mount technology. In some embodiments, the electronic component 50 is a chip.

[0031] Step S10, please refer to Figure 8, place the circuit board 10 on which the electronic components 50 are mounted in the reflow oven and heat it so that the solder balls 51 and the solder paste 40 melt and bond together to obtain the circuit board 100.

[0032] During the reflow soldering process, the molten solder paste 40 is soldered to the sidewall of the groove 311, improving the bonding force between the solder paste 40 and the conductive post 31; and the molten solder ball 51 is soldered to the surface of the conductive post 31, improving the bonding force between the solder ball 51 and the conductive post 31. In addition, the increased solder capacity of the sidewall of the conductive post 31 helps maintain a small gap between adjacent conductive posts 31; when molten solder overflows from the surface of the conductive post 31, it flows along the sidewall of the conductive post 31 into the space between adjacent conductive posts 31. When the overflowing solder is small, it can only cover the sidewall of the conductive post 31 without flowing into the space between adjacent conductive posts 31.

[0033] In some embodiments, the method of manufacturing a circuit board further includes the following steps: forming a solder resist layer (not shown) on the surface of the circuit board, the solder resist layer covering the surface of the third conductor layer away from the second substrate layer and the surface of the first conductor layer away from the first substrate layer.

[0034] In some embodiments, the method of manufacturing the circuit board further includes the following steps: filling the opening with adhesive, wherein the adhesive fills the gap between adjacent conductive posts and the gap between the conductive posts and the sidewall of the opening, thereby improving stability.

[0035] Referring to FIG8, one embodiment of this application provides a circuit board 100, including a circuit board 10, a plurality of conductive pillars 31, a plurality of solder pastes 40, and electronic components 50. The circuit board 10 includes a first substrate 11, which includes a first substrate layer 111 and a first conductor layer 112 and a second conductor layer 113 disposed on two opposite surfaces of the first substrate layer 111. The first conductor layer 112 includes a plurality of spaced-apart connecting pads 112a. The second conductor layer 113 has an opening 120 exposing the first substrate layer 111, and the first substrate layer 111 has a plurality of through holes 110 exposing the plurality of connecting pads 112a. The plurality of through holes 110 are exposed in the opening 120. The conductive pillars 31 are accommodated in the opening 120 and pass through the through holes 110 to connect to the connecting pads 112a. The conductive pillars 31 are disposed separately from the second conductor layer 113. The conductive post 31 has a groove 311 on its surface away from the connecting pad 112a, and solder paste 40 is accommodated in the groove 311. The electronic component 50 includes a plurality of solder balls 51, which cover at least a portion of the surface of the conductive post 31 away from the connecting pad 112a and are in contact with the solder paste 40.

[0036] In some embodiments, the circuit board 100 further includes a plurality of fillers 20. The fillers 20 are disposed within the conductive posts 31 and supported on the connecting pads 112a. In some embodiments, the fillers 20 are solder paste. In other embodiments, the fillers 20 are adhesives or solid refrigerants.

[0037] In some embodiments, the circuit board 100 further includes a second substrate 12 and an adhesive layer 13, wherein the second substrate 12 is bonded to the surface of the second conductor layer 113 away from the first substrate layer 111 by means of the adhesive layer 13. An opening 120 extends through the second substrate 12 and the adhesive layer 13, and a plurality of conductive pillars 31 are accommodated in the opening 120 and disposed away from the sidewall of the opening 120.

[0038] In some embodiments, both the side surface of the solder paste 40 and the side surface of the filler 20 are beveled.

[0039] In the circuit board and its manufacturing method provided in the embodiments of this application, by configuring conductive pillars 31 connected to the connecting pads 112a, a groove 311 is formed on the conductive pillar 31, and solder paste 40 is filled in the groove 311. The electronic components 50 are soldered to the solder paste 40 contained in the conductive pillar 31 and the surface of the conductive pillar 31 by solder balls 51, which increases the contact area between the solder and the conductive pillar 31, which is beneficial to improve the bonding force and thus improve the soldering strength. In addition, the conductive pillars 31 and the connecting pads 112a are manufactured by laser cutting process, which is beneficial to reduce the spacing between adjacent connecting pads 112a / conductive pillars 31, which is beneficial to miniaturization.

[0040] In addition, those skilled in the art can make other changes within the spirit of the present invention. Of course, all such changes made in accordance with the spirit of the present invention should be included within the scope of protection claimed by the present invention. [Simplified Explanation of the Diagram]

[0007] Figure 1 is a cross-sectional schematic diagram of a circuit board provided in one embodiment of this application.

[0008] Figure 2 is a cross-sectional schematic diagram of a through hole formed on the first substrate of the circuit board shown in Figure 1.

[0009] Figure 3 is a cross-sectional schematic diagram of the through hole shown in Figure 2 after the filler is formed.

[0010] Figure 4 is a cross-sectional schematic diagram of the through hole shown in Figure 3 after it is filled with conductive material.

[0011] Figure 5 is a cross-sectional schematic diagram of the conductive column formed after removing part of the conductive material shown in Figure 4.

[0012] Figure 6 is a cross-sectional schematic diagram of the conductive pillars shown in Figure 5 filled with solder paste and the connection pads formed on the circuit board.

[0013] Figure 7 is a cross-sectional schematic diagram of the conductor shown in Figure 6 after electronic components are installed.

[0014] Figure 8 is a schematic diagram of the circuit board provided in one embodiment of this application. [Biomaterial Storage]

[0042] None

Claims

1. A circuit board, wherein, include: A circuit board, comprising a first substrate, the first substrate including a first substrate layer and a first conductor layer and a second conductor layer disposed on two opposite surfaces of the first substrate layer, the first conductor layer including a plurality of connecting pads, the second conductor layer having an opening exposing the first substrate layer, the first substrate layer having a plurality of through holes exposed in the opening, and the plurality of connecting pads respectively exposed in the plurality of through holes; a plurality of conductive pillars, the plurality of conductive pillars being accommodated in the opening and respectively passing through the plurality of through holes and contacting the plurality of connecting pads, the conductive pillars being disposed separately from the second conductor layer, and the surface of the conductive pillars facing away from the connecting pads having a groove; solder paste, the solder paste being accommodated in the groove; and electronic components, the electronic components including solder balls, the solder balls covering the surface of the conductive pillars facing away from the connecting pads and contacting the solder paste.

2. The circuit board as claimed in claim 1, wherein, The circuit board also includes a filler material disposed within the conductive pillar and supported on the connecting pad.

3. The circuit board as claimed in claim 2, wherein, The filler is solder paste.

4. The circuit board as claimed in claim 2, wherein, The filler is an adhesive.

5. The circuit board as claimed in claim 1, wherein, The circuit board further includes a second substrate and an adhesive layer, wherein the second substrate is bonded to the surface of the second conductor layer opposite to the first substrate layer by the adhesive layer, and the opening extends through the adhesive layer and the second substrate.

6. A method for manufacturing a circuit board, wherein, The process includes the following steps: providing a circuit board, the circuit board including a first substrate, the first substrate including a first substrate layer and a first conductor layer and a second conductor layer disposed on two opposing surfaces of the first substrate layer; forming a plurality of through holes on the first substrate, the through holes penetrating the second conductor layer and the first substrate layer, and exposing a portion of the first conductor layer; filling the through holes with a conductive material, the conductive material filling the plurality of through holes and covering the surface of the second conductor layer, the conductive material also being in contact with the first conductor layer; removing a portion of the conductive material to form a plurality of spaced conductive pillars, the plurality of conductive pillars respectively filling the plurality of through holes and connecting to the first conductor layer; removing a portion of the second conductor layer, so that the conductive pillars are disposed apart from the second conductor layer; forming grooves on the surface of the conductive pillars away from the first conductor layer; filling the grooves with solder paste; and fabricating a plurality of connection pads on the first conductor layer, the plurality of connection pads corresponding to and connected to the plurality of conductive pillars one by one. Electronic components are mounted on a plurality of conductive pillars, each electronic component comprising a plurality of solder balls, each solder ball making contact with a plurality of solder pastes in a corresponding manner; the circuit board on which the electronic components are mounted is placed in a reflow oven and heated, causing the solder balls and solder pastes to melt and bond together.

7. The method for manufacturing a circuit board as described in claim 6, wherein, Before the step "filling the through hole with conductive material", the method further includes the following steps: forming a filler in the through hole, the filler being supported on the first conductor layer; wherein, after forming the plurality of conductive pillars, the plurality of conductive pillars respectively cover the plurality of fillers.

8. A method for manufacturing a circuit board as described in claim 7, wherein, The filler is solder paste.

9. A method for manufacturing a circuit board as described in claim 7, wherein, The filler is an adhesive.

10. A method for manufacturing a circuit board as described in claim 6, wherein, A plurality of the connecting pads are fabricated on the first conductor layer using a laser cutting process.

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