Circuit board structure comprising different metal materials with different coefficients of thermal expansion and method for manufacturing same

Abstract

A circuit board structure including different thermal expansion coefficient metal materials and a manufacturing method thereof are disclosed. The circuit board structure includes a core substrate layer, a first circuit layer formed on the core substrate layer, and an insulating dielectric layer formed on the first circuit layer. A signal via is formed in the insulating dielectric layer. The circuit board structure further includes a first metal material and a second metal material formed in the signal via. The first metal material is formed on the first circuit layer, and the second metal material is formed on the first metal material. The first metal material has a first thermal expansion coefficient, the second metal material has a second thermal expansion coefficient, and the second thermal expansion coefficient is greater than the first thermal expansion coefficient. Thus, the signal connection can be maintained when the via of the circuit board is broken.

Description

Technical Field

[0001] This application relates to a circuit board structure, and more particularly to a circuit board structure containing metal materials with different coefficients of thermal expansion and a method for manufacturing the same. Background Technology

[0002] like Figure 1 As shown, in the prior art, adjacent circuit layers L in circuit board E can be connected via, for example, via vias Via and a metal material M (e.g., copper) filling them. During the fabrication of vias Via, the metal material M is primarily filled into the vias through a via-filling electroplating process. Before electroplating, the surfaces of circuit board E to be plated generally need to be cleaned to ensure the plating quality meets requirements. Figure 2 As shown, if the surface to be plated in the circuit board E is not sufficiently cleaned, the final circuit board E may experience interface breakage C at the junction of the metal material M in the via Via and the circuit L or copper layer due to heat during subsequent operation. This would prevent electrical signals from being transmitted between the two adjacent circuit layers L. Consequently, the circuit board E may be deemed functionally faulty due to signal breakage.

[0003] Therefore, the inventor, recognizing that the aforementioned deficiencies could be improved, devoted himself to research and applied theoretical principles, and finally proposed this application with a reasonable design that effectively improves the aforementioned deficiencies. Summary of the Invention

[0004] This application aims to provide a circuit board structure containing metal materials with different coefficients of thermal expansion, in order to effectively improve the shortcomings that may occur in existing torsion plates.

[0005] This application discloses a circuit board structure comprising metal materials with different coefficients of thermal expansion, including: a core substrate layer; a first circuit layer formed on the core substrate layer; an insulating dielectric layer formed on the first circuit layer; wherein a signal via is formed on the inner side of the insulating dielectric layer; a first metal material formed in the signal via and on the first circuit layer; and a second metal material formed in the signal via and on the first metal material; wherein the first metal material has a first coefficient of thermal expansion, the second metal material has a second coefficient of thermal expansion, and the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion.

[0006] Optionally, when the circuit board structure undergoes a high-temperature operation, the volume expansion rate of the second metal material is greater than that of the first metal material, so that the second metal material generates a compressive stress in the direction of the first metal material, and the first metal material can continuously contact the first circuit layer and maintain electrical connection through the compression of the second metal material.

[0007] Optionally, in the signal via, the first metal material has a first thickness, the second metal material has a second thickness, and the second thickness of the second metal material is greater than the first thickness of the first metal material.

[0008] Optionally, the sum of the first thickness and the second thickness is defined as the total thickness, wherein the first thickness of the first metal material accounts for 15% to 45% of the total thickness, and the second thickness of the second metal material accounts for 55% to 85% of the total thickness.

[0009] Optionally, the first coefficient of thermal expansion of the first metallic material and the second coefficient of thermal expansion of the second metallic material are respectively between 10 and 40*10. -6 / K@20℃, and the difference between the second coefficient of thermal expansion and the first coefficient of thermal expansion is not less than 1*10 -6 / K@20℃.

[0010] Optionally, the circuit board structure further includes a second circuit layer formed on the surface of the insulating dielectric layer away from the first circuit layer; wherein the first circuit layer is connected to the first metal material, and the second circuit layer is connected to the second metal material.

[0011] Optionally, the first metal material has a base and a protrusion formed on the base, and the width of the base is greater than the width of the protrusion, so that the first metal material presents a convex structure.

[0012] Optionally, the base is formed on the first circuit layer, and the protrusion is embedded in the second metal material, so that the first metal material is fitted into the second metal material.

[0013] Optionally, when the circuit board structure cools down, the volume shrinkage rate of the first metal material is greater than that of the second metal material, causing a bending stress to be generated at the base in the direction of the protrusion.

[0014] This application also discloses a method for manufacturing a circuit board structure, comprising: providing a core substrate layer; forming a first circuit layer on one side surface of the core substrate layer; forming an insulating dielectric layer on the side surface of the first circuit layer away from the core substrate layer; forming a signal via inside the insulating dielectric layer, wherein the signal via is connected to the upper and lower surfaces of the insulating dielectric layer; forming a first metal material in the signal via and on the first circuit layer; wherein the first metal material has a first coefficient of thermal expansion; and forming a second metal material in the signal via and on the first metal material; wherein the second metal material has a second coefficient of thermal expansion, and the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion.

[0015] In summary, the circuit board structure and manufacturing method of the present application containing metal materials with different coefficients of thermal expansion can maintain signal connection even when the via breaks by "stack and thermal expansion coefficient design of the first and second metal materials in the signal via".

[0016] To further understand the features and technical content of this application, please refer to the following detailed description and drawings of this application. However, these descriptions and drawings are only used to illustrate this application and are not intended to limit the scope of protection of this application in any way. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of a circuit board structure in the prior art.

[0018] Figure 2 This is a schematic diagram showing the interface fracture that occurs at the junction of the metal material and the copper layer in the through-hole of a circuit board structure in the prior art.

[0019] Figure 3 This is a cross-sectional schematic diagram of the circuit board structure according to the first embodiment of this application.

[0020] Figure 4 for Figure 1 A schematic diagram showing the downward compressive stress generated by the second metallic material.

[0021] Figure 5 for Figure 1 Another schematic diagram of a variation of the circuit board structure.

[0022] Figure 6 This is a cross-sectional schematic diagram of the circuit board structure according to the second embodiment of this application.

[0023] Figure 7 for Figure 6 A magnified view of a portion of region VII in the middle.

[0024] Figure 8 for Figure 6 A schematic diagram of the first metallic material generating an inward bending stress.

[0025] Figure 9 This is a flowchart illustrating the manufacturing method of the circuit board structure according to the third embodiment of this application. Detailed Implementation

[0026] The following specific embodiments illustrate the implementation methods disclosed in this application. Those skilled in the art can understand the advantages and effects of this application from the content disclosed in this specification. This application can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this application. Furthermore, the accompanying drawings of this application are for simple illustration only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this application in detail, but the disclosed content is not intended to limit the scope of protection of this application.

[0027] It should be understood that while terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein should, as appropriate, include any combination of one or more of the related listed items.

[0028] First Embodiment

[0029] Please see Figure 3 and Figure 4 As shown, the first embodiment of this application provides a circuit board structure 100, and in particular, a circuit board structure 100 containing metal materials with different coefficients of thermal expansion, which can improve the problem in the prior art that electrical signals cannot be transmitted due to the breakage at the interface between the via and the copper circuit layer.

[0030] To achieve the above objectives, the circuit board structure 100 includes: a core substrate layer 1, a first circuit layer 2, and an insulating dielectric layer 3. The first circuit layer 2 is formed on one side surface of the core substrate layer 1, and the insulating dielectric layer 3 is formed on the side surface of the first circuit layer 2 away from the core substrate layer 1.

[0031] In this embodiment, the core substrate layer 1 may be made of, for example, glass fiber cloth (e.g., FR-4), the first circuit layer 2 may be made of, for example, copper metal circuit layer, and the insulating dielectric layer 3 may be made of, for example, a prepreg (e.g., Prepreg, PP adhesive), but this application is not limited to these.

[0032] Furthermore, a signal via 4 is formed on the inner side of the insulating dielectric layer 3, and the signal via 4 is connected to the upper and lower surfaces of the insulating dielectric layer 3, and corresponds in position to a portion of the first circuit layer 2. In this embodiment, the signal via 4 is a laser-drilled hole, and has a hole shape that is wider at the top and narrower at the bottom, but this application is not limited to this.

[0033] Furthermore, the circuit board structure 100 is filled with a first metal material 41 and a second metal material 42 in sequence inside the signal through hole 4, from the direction close to the first circuit layer 2 to the direction away from the first circuit layer 2 (or from its bottom to its top).

[0034] In other words, the first metal material 41 is formed inside the signal via 4 and is formed on the first circuit layer 2, directly connected to and in contact with the first circuit layer 2. Furthermore, the second metal material 42 is formed inside the signal via 4 and is formed on the surface of the first metal material 41 away from the first circuit layer 2, directly connected to and in contact with the first metal material 41.

[0035] The first metal material 41 and the second metal material 42 may be formed, for example, by at least one of a metal electroplating process, an electroless electroplating process, a metal physical deposition process, and a metal chemical deposition process.

[0036] In this embodiment, both the first metal material 41 and the second metal material 42 are in contact with the sidewall inside the signal conduction hole 4 (e.g., Figure 3 (as shown), but this application is not limited thereto.

[0037] like Figure 5 As shown, in another embodiment of this application, the first metal material 41 may also be formed on the first circuit layer 2 and extend to cover all the sidewalls within the signal via 4. The second metal material 42 fills the remaining portion of the signal via 4 and does not contact the sidewalls within the signal via 4.

[0038] Please continue reading. Figure 3 and Figure 4As shown, further, the first metal material 41 has a first coefficient of thermal expansion α1, and the second metal material 42 has a second coefficient of thermal expansion α2. The second coefficient of thermal expansion α2 of the second metal material 42 is greater than the first coefficient of thermal expansion α1 of the first metal material 41.

[0039] Accordingly, Figure 4 As shown, when the circuit board structure 100 undergoes a high-temperature operation, the volume expansion rate of the second metal material 42 is greater than that of the first metal material 41, so that the second metal material 42 generates a compressive stress F1 in the direction of the first metal material 41, and the first metal material 41 can continuously contact the first circuit layer 2 through the compression of the second metal material 42 to maintain electrical connection.

[0040] The high-temperature operation may be, for example, high-temperature reflow, but this application is not limited to this.

[0041] According to the above configuration, even if an interface break occurs at the junction of the first metal material 41 and the first circuit layer 2, the first metal material 41 will still be subjected to the compressive stress F1 and will continue to be connected and in contact with the first circuit layer 2. Accordingly, the problem of electrical signal transmission failure caused by the breakage at the interface between the via and the copper circuit layer in the prior art can be effectively solved.

[0042] It is worth mentioning that the coefficient of thermal expansion (CTE) referred to in this article is a coefficient that shows the regularity of changes in the geometric properties of a material as temperature rises and falls under the influence of thermal expansion and contraction. The coefficient of thermal expansion of the first and second metallic materials can be the linear coefficient of thermal expansion (CLTE), but is not limited to it.

[0043] It is worth mentioning that, in some embodiments of this application, the first metal material 41 and the second metal material 42 filling the signal via 4 can be selected from at least one of the group of materials consisting of copper, silver, gold, zinc and aluminum, but this application is not limited thereto.

[0044] Regarding the linear thermal expansion coefficient α, for example, the linear thermal expansion coefficient α of copper is 16.5 × 10⁻⁶. -6 / K@20℃. The linear thermal expansion coefficient α of the silver metal is 19.5*10. -6 / K@20℃.

[0045] The linear thermal expansion coefficient α of the gold metal is 14.2 × 10⁻⁶.-6 / K@20℃. And the linear thermal expansion coefficient α of the zinc metal is 36.0*10. -6 / K@20℃. Furthermore, the linear thermal expansion coefficient α of the aluminum metal is 23.0*10. -6 / K@20℃.

[0046] In some embodiments of this application, the second metal material 42 may be, for example, copper (α2 = 16.5 * 10⁻⁶). -6 / K@20℃), and the first metallic material 41 can be, for example, gold (α1=

[0047] 14.2*10 -6 / K@20℃). Alternatively, the second metallic material 42 can be, for example, silver (α2=19.5*10). -6 / K@20℃, and the first metallic material 41 can be, for example, copper (α2=16.5*10 -6 / K@20℃).

[0048] It is worth mentioning that the second thermal expansion coefficient α2 of the second metal material 42 in the above embodiments is greater than the first thermal expansion coefficient α1 of the first metal material 41.

[0049] From another perspective, the first thermal expansion coefficient α1 of the first metallic material 41 and the second thermal expansion coefficient α2 of the second metallic material 42 are respectively between 10 and 40*10. -6 / K@20℃.

[0050] Furthermore, the difference between the second thermal expansion coefficient α2 of the second metal material 42 and the first thermal expansion coefficient α1 of the first metal material 41 is not less than 1*10. -6 / K@20℃, and preferably not less than 2*10 -6 / K@20℃.

[0051] However, it should be noted that the above embodiments are merely illustrative examples, and this application is not limited to the above embodiments.

[0052] Please continue reading. Figure 3 and Figure 4 In the signal via 4, the first metal material 41 has a first thickness T1, and the second metal material 42 has a second thickness T2. The second thickness T2 of the second metal material 42 is greater than the first thickness T1 of the first metal material 41.

[0053] In some embodiments of this application, the sum of the first thickness T1 and the second thickness T2 is defined as the total thickness. The first thickness T1 of the first metal material 41 accounts for 15% to 45% of the total thickness, and preferably 20% to 40%. Furthermore, the second thickness T2 of the second metal material 42 accounts for 55% to 85% of the total thickness, and preferably 60% to 80%.

[0054] Based on the above thickness ratio, the second metal material 42 can generate more sufficient compressive stress F1 on the first metal material 41 during high-temperature operation, so that the first metal material 41 can continuously contact and electrically connect with the first circuit layer 2.

[0055] Furthermore, in this embodiment, the circuit board structure 100 further includes a second wiring layer 5, which is formed on the side surface of the insulating dielectric layer 3 away from the first wiring layer 2. In other words, the first wiring layer 2 and the second wiring layer 5 are respectively formed on two opposite side surfaces of the insulating dielectric layer 3. The first wiring layer 2 is connected to the first metal material 41, and the second wiring layer 5 is connected to the second metal material 42.

[0056] In one embodiment of this application, the first circuit layer 2 and the first metal material 41 may be formed in different electroplating processes or metal deposition processes, and the second circuit layer 5 may be formed in the same electroplating process or metal deposition process as the second metal material 42, but this application is not limited thereto.

[0057] Second Embodiment

[0058] Please see Figures 6 to 8 As shown, a second embodiment of this application further provides a circuit board structure 100'. The circuit board structure 100' includes: a core substrate layer 1, a first circuit layer 2, an insulating dielectric layer 3, and a second circuit layer 5. The first circuit layer 2 is formed on one side surface of the core substrate layer 1, the insulating dielectric layer 3 is formed on the side surface of the first circuit layer 2 away from the core substrate layer 1, and the second circuit layer 5 is formed on the side surface of the insulating dielectric layer 3 away from the first circuit layer 2.

[0059] A signal via 4 is formed on the inner side of the insulating dielectric layer 3, and the signal via 4 connects to the upper and lower surfaces of the insulating dielectric layer 3. A first metal material 41 and a second metal material 42 are sequentially filled inside the signal via 4. The first metal material 41 is formed on the first circuit layer 2, and the second metal material 42 is formed on the first metal material 41. The first metal material 41 has a first coefficient of thermal expansion α1, and the second metal material 42 has a second coefficient of thermal expansion α2, wherein the second coefficient of thermal expansion α2 is greater than the first coefficient of thermal expansion α1. The first metal material 41 is connected to the first circuit layer 2, and the second metal material 42 is connected to the second circuit layer 5, thereby electrically connecting the first circuit layer 2 and the second circuit layer 5.

[0060] The circuit board structure 100' provided in the second embodiment of this application is substantially the same as the circuit board structure 100 of the first embodiment described above. The main difference is that the first metal material 41 in the second embodiment of this application further has a base 411 and a protrusion 412 formed on the base 411. The width of the base 411 is greater than the width of the protrusion 412, so that the second metal material 42 presents a U-shaped structure.

[0061] Furthermore, the base 411 is formed on and directly connected to the first circuit layer 2. The protrusion 412 is embedded in the second metal material 42, so that the first metal material 41 is fitted into the second metal material 42. Accordingly, the contact area between the first metal material 41 and the second metal material 42 can be increased to effectively increase the bonding between dissimilar materials.

[0062] Similar to the first embodiment described above, when the circuit board structure 100' undergoes a high-temperature operation, the volume expansion rate of the second metal material 42 will be greater than that of the first metal material 41, so that the second metal material 42 generates a compressive stress F1 in the direction of the first metal material 41, and the first metal material 41 can continuously contact the first circuit layer 2 through the compression of the second metal material 42 to maintain electrical connection.

[0063] Furthermore, when the circuit board structure 100' is cooled down by the high-temperature operation, the volume shrinkage rate of the first metal material 41 will be greater than that of the second metal material 42, causing a bending stress F2 to be generated in the base 411 towards the protrusion 412 (e.g., Figure 8 As shown), this allows for a tighter bond between the first metal material 41 and the second metal material 42, and downward contact with the first circuit layer 2 to maintain electrical connection.

[0064] According to the above configuration, even if an interface break occurs at the junction of the first metal material 41 and the first circuit layer 2, the first metal material 41 will still remain connected and in contact with the first circuit layer 2. Therefore, the problem of electrical signal transmission failure caused by a break at the interface between the via and the copper circuit layer in the prior art can be effectively solved.

[0065] Third Embodiment

[0066] The above describes the structural and material features of the circuit board structures 100 and 100' according to embodiments of this application. The manufacturing method of the circuit board structures according to embodiments of this application will be described below. Figure 9 As shown, the manufacturing method of the circuit board structure includes steps S110 to S160.

[0067] It should be noted that the order of the steps and the actual operation method described in this embodiment can be adjusted according to the needs, and are not limited to those described in this embodiment.

[0068] Step S110 includes providing a core substrate layer 1. Step S120 includes forming a first circuit layer 2 on one side surface of the core substrate layer 1.

[0069] Step S130 includes: forming an insulating dielectric layer 3 on the surface of the first circuit layer 2 away from the core substrate layer 1.

[0070] Step S140 includes: forming a signal via 4 inside the insulating dielectric layer 3, and the signal via 4 is connected to the upper and lower surfaces of the insulating dielectric layer 3 and corresponds in position to a portion of the first circuit layer 2.

[0071] Step S150 includes: forming a first metal material 41 within the signal via 4, and on the first circuit layer 2, and directly connected to and in contact with the first circuit layer 2. The first metal material 41 may have the following characteristics: Figure 3 The flat, layered shape shown, or the first metal material 41 may also have such a shape. Figure 6 The figure shows a convex shape. The first metal material 41 has a first coefficient of thermal expansion α1.

[0072] Step S160 includes: forming a second metal material 42 within the signal via 4 and on the first metal material 41, and being directly connected to and in contact with the first metal material 41. The second metal material 42 has a second coefficient of thermal expansion α2, and the second coefficient of thermal expansion α2 of the second metal material 42 is greater than the first coefficient of thermal expansion α1 of the first metal material 41.

[0073] In some embodiments of this application, the first metal material 41 and the second metal material 42 may be formed in the signal via 4 by at least one of a metal electroplating process, an electroless electroplating process, a metal physical deposition process, and a metal chemical deposition process, respectively.

[0074] Beneficial effects of the invention

[0075] One of the advantages of this application is that the circuit board structure and manufacturing method of the circuit board containing metal materials with different coefficients of thermal expansion provided by this application can maintain the signal connection even when the via breaks by "stack and thermal expansion coefficient design of the first metal material and the second metal material in the signal via".

[0076] The content disclosed above is only a preferred and feasible embodiment of this application, and is not intended to limit the scope of the patent application. Therefore, all equivalent technical changes made using the content of this application specification and drawings are included in the scope of the patent application.

Claims

1. A circuit board structure comprising metallic materials with different coefficients of thermal expansion, characterized in that, The circuit board structure includes: One core substrate layer; A first circuit layer is formed on the core substrate layer; An insulating dielectric layer is formed on the first circuit layer; wherein a signal via is formed on the inner side of the insulating dielectric layer; A first metallic material is formed within the signal via and on the first circuit layer; and A second metallic material is formed within the signal via and on the first metallic material; Wherein, the first metal material has a first coefficient of thermal expansion, the second metal material has a second coefficient of thermal expansion, and the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion.

2. The circuit board structure comprising metal materials with different coefficients of thermal expansion according to claim 1, characterized in that, When the circuit board structure is subjected to a high-temperature operation, the volume expansion rate of the second metal material is greater than that of the first metal material, so that the second metal material generates a compressive stress in the direction of the first metal material, and the first metal material can continuously contact the first circuit layer through the compression of the second metal material and maintain electrical connection.

3. The circuit board structure comprising metal materials with different coefficients of thermal expansion according to claim 1, characterized in that, In the signal via, the first metal material has a first thickness, the second metal material has a second thickness, and the second thickness of the second metal material is greater than the first thickness of the first metal material.

4. The circuit board structure comprising metallic materials with different coefficients of thermal expansion according to claim 3, characterized in that, The sum of the first thickness and the second thickness is defined as the total thickness, wherein the first thickness of the first metal material accounts for 15% to 45% of the total thickness, and the second thickness of the second metal material accounts for 55% to 85% of the total thickness.

5. The circuit board structure comprising metallic materials with different coefficients of thermal expansion according to claim 1, characterized in that, The first coefficient of thermal expansion of the first metallic material and the second coefficient of thermal expansion of the second metallic material are respectively between 10 and 40*10. -6 / K@20℃, and the difference between the second coefficient of thermal expansion and the first coefficient of thermal expansion is not less than 1*10 -6 / K@20℃.

6. The circuit board structure comprising metallic materials with different coefficients of thermal expansion according to claim 1, characterized in that, The circuit board structure containing metal materials with different coefficients of thermal expansion further includes a second circuit layer formed on the surface of the insulating dielectric layer away from the first circuit layer; wherein the first circuit layer is connected to the first metal material, and the second circuit layer is connected to the second metal material.

7. The circuit board structure comprising metallic materials with different coefficients of thermal expansion according to claim 1, characterized in that, The first metal material has a base and a protrusion formed on the base, and the width of the base is greater than the width of the protrusion, so that the first metal material presents a convex structure.

8. The circuit board structure comprising metal materials with different coefficients of thermal expansion according to claim 7, characterized in that, The base is formed on the first circuit layer, and the protrusion is embedded in the second metal material so that the first metal material is fitted into the second metal material.

9. The circuit board structure comprising metallic materials with different coefficients of thermal expansion according to claim 8, characterized in that, When the circuit board structure cools down, the volume shrinkage rate of the first metal material is greater than that of the second metal material, causing a bending stress to be generated at the base in the direction of the protrusion.

10. A method for manufacturing a circuit board structure, characterized in that, The method for manufacturing the circuit board structure includes: Provide a core substrate layer; A first circuit layer is formed on one side surface of the core substrate layer; An insulating dielectric layer is formed on the surface of the first circuit layer away from the core substrate layer; A signal via is formed inside the insulating dielectric layer, and the signal via is connected to the upper and lower surfaces of the insulating dielectric layer; A first metallic material is formed inside the signal via and on the first circuit layer; Wherein, the first metallic material has a first coefficient of thermal expansion; and A second metallic material is formed within the signal via and on the first metallic material; wherein the second metallic material has a second coefficient of thermal expansion, and the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion.

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