阅读说明：本技术 一种超薄基板结构的制造方法 (Manufacturing method of ultrathin substrate structure ) 是由 陈先明 赵江江 冯磊 宝玥 黄本霞 洪业杰 于 2020-12-16 设计创作，主要内容包括：本发明提供了一种超薄基板结构的制造方法,包括如下步骤：(a)准备承载板,在所述承载板的表面形成第一阻焊层,并在所述第一阻焊层内形成第一阻焊开窗；(b)在所述第一阻焊层上形成第一金属种子层,在所述第一金属种子层上形成第一布线层、在所述第一布线层上的第一通孔柱层、覆盖所述第一布线层和所述第一通孔柱层的第一介电层和在所述第一介电层上的第二布线层,其中所述第一布线层和所述第二布线层通过所述第一通孔柱层导通连接；(c)在所述第二布线层上形成第二阻焊层,并在所述第二阻焊层内形成第二阻焊开窗；(d)移除所述承载板。(The invention provides a manufacturing method of an ultrathin substrate structure, which comprises the following steps: (a) preparing a bearing plate, forming a first solder mask layer on the surface of the bearing plate, and forming a first solder mask windowing in the first solder mask layer; (b) forming a first metal seed layer on the first solder resist layer, forming a first wiring layer on the first metal seed layer, a first via post layer on the first wiring layer, a first dielectric layer covering the first wiring layer and the first via post layer, and a second wiring layer on the first dielectric layer, wherein the first wiring layer and the second wiring layer are conductively connected through the first via post layer; (c) forming a second solder mask layer on the second wiring layer, and forming a second solder mask windowing window in the second solder mask layer; (d) and removing the bearing plate.)

1. A manufacturing method of an ultrathin substrate structure comprises the following steps:

(a) preparing a bearing plate, forming a first solder mask layer on the surface of the bearing plate, and forming a first solder mask windowing in the first solder mask layer;

(b) forming a first metal seed layer on the first solder resist layer, forming a first wiring layer on the first metal seed layer, a first via post layer on the first wiring layer, a first dielectric layer covering the first wiring layer and the first via post layer, and a second wiring layer on the first dielectric layer, wherein the first wiring layer and the second wiring layer are conductively connected through the first via post layer;

(c) forming a second solder mask layer on the second wiring layer, and forming a second solder mask windowing window in the second solder mask layer;

(d) and removing the bearing plate.

2. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein the carrier plate comprises a support layer and a metal foil on at least one surface of the support layer.

3. The method of manufacturing an ultra-thin substrate structure of claim 2, wherein the copper foil is a double-layer metal foil, and the double-layer metal foil is attached together by physical pressing.

4. The manufacturing method of an ultra-thin substrate structure according to claim 2, wherein the copper foil is a single-layer metal foil, and a release layer is provided between the support layer and the single-layer metal foil.

5. The method of manufacturing an ultra-thin substrate structure of claim 2, wherein the support layer comprises a prepreg layer.

6. The method of claim 4, wherein the release layer comprises a heat removable foam layer.

7. The method of manufacturing an ultra-thin substrate structure of claim 2, wherein the metal foil comprises copper, aluminum, or nickel.

8. The method of claim 1, wherein the first metal seed layer comprises titanium, copper, titanium tungsten alloy, or combinations thereof.

9. The method of claim 8, wherein the first metal seed layer comprises a titanium layer and a copper layer on the titanium layer.

10. The method of manufacturing an ultra-thin substrate structure according to claim 9, wherein the titanium layer has a thickness of 0.1-0.3 μm and the copper layer has a thickness of 0.8-2.0 μm.

11. The method of manufacturing an ultra-thin substrate structure according to claim 10, wherein the titanium layer has a thickness of 0.1 μm and the copper layer has a thickness of 1.0 μm.

12. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein the height of the first via post layer is 15-30 μ ι η.

13. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein the thickness of the first dielectric layer is 15-30 μ ι η.

14. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein the thickness of the first and second wiring layers is 8-15 μ ι η.

15. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein step (b) comprises:

(b1) applying a first metal seed layer on the first solder mask layer;

(b2) applying a first photoresist layer on the first metal seed layer, and patterning the first photoresist layer to form a first characteristic pattern;

(b3) electroplating the first characteristic pattern to form a first wiring layer;

(b4) applying a second photoresist layer outside the first wiring layer, and patterning the second photoresist layer to form a second feature pattern;

(b5) electroplating the second characteristic pattern to form a first through hole column layer;

(b6) removing the first photoresist layer and the second photoresist layer, and etching away the exposed first metal seed layer;

(b7) laminating a dielectric material to form a first dielectric layer, and thinning the first dielectric layer to expose the end part of the first through hole column layer;

(b8) applying a second metal seed layer on the first dielectric layer exposing the end of the first via post layer;

(b9) applying a third photoresist layer on the second metal seed layer, and patterning the third photoresist layer to form a third feature pattern;

(b10) electroplating the third characteristic pattern to form a second wiring layer;

(b11) and removing the third photoresist layer, and etching away the exposed second metal seed layer.

16. The method of manufacturing an ultra-thin substrate structure of claim 15, wherein step (b7) includes integrally thinning the first dielectric layer by lapping or plasma etching to expose an end portion of the first via post layer.

17. The method of claim 15, wherein step (b7) comprises locally thinning the first dielectric layer by laser machining or drilling or by exposure development to expose an end of the first via post layer.

18. The method of manufacturing an ultra-thin substrate structure according to claim 2, wherein the step (d) further comprises removing the metal foil on the first solder resist layer by etching after removing the carrier board by separating the support layer and the metal foil.

19. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein step (b) comprises:

(b 1') applying a first metal seed layer on the first solder mask layer;

(b 2') applying a first photoresist layer on the first metal seed layer and patterning the first photoresist layer to form a first feature pattern;

(b 3') electroplating the first feature pattern to form a first wiring layer;

(b 4') removing the first photoresist layer, etching away the exposed first metal seed layer;

(b 5') laminating a dielectric material on the first wiring layer to form a first dielectric layer;

(b 6') forming a first via in the first dielectric layer and applying a second metal seed layer on the first dielectric layer;

(b 7') applying a third photoresist layer on the second metal seed layer, patterning the third photoresist layer to form a third feature pattern exposing the first via;

(b 8') electroplating the third feature pattern while forming a first via post layer and a second wiring layer;

(b 9') removing the third photoresist layer and etching away the exposed second metal seed layer.

20. The method of manufacturing an ultra-thin substrate structure of claim 1, wherein the step (c) further comprises: and continuously adding a third wiring layer formed on a second dielectric layer on the second wiring layer, forming a second solder mask layer on the third wiring layer, and forming a second solder mask windowing window in the second solder mask layer.

Technical Field

The present invention relates to a method of manufacturing an ultra-thin substrate structure.

Background

With the increasing demand for package size, the thickness of the package substrate, which is an important component of the package, is also required to be increased. Ultra-thin substrates are one way to reduce the thickness of the substrate. The ultra-thin substrate is very thin (two-layer plate is usually as low as 60um or even lower), is inconvenient to process in the processing process, is incompatible with the conventional substrate processing technology in many aspects, is extremely easy to damage in the processing process, and has insufficient supporting strength in post-process reprocessing operation after the substrate is manufactured.

Chinese patent publication CN106409688A discloses a processing method of an ultra-thin coreless package substrate, which is implemented as follows: firstly, prepare the loading board, the loading board includes compound copper foil layer, compound copper foil separable ultra-thin copper foil layer, then make first circuit layer on ultra-thin copper foil layer, then pressfitting insulating layer and outer copper foil layer on first circuit layer, then make the conducting hole, then make second circuit layer and a second floor conducting hole on outer copper foil, then hinder to weld and the surface coating to the second circuit layer handles, then divide the board, then bond the ultra-thin base plate of separation to the backup pad, the backup pad bonds in the one side at second circuit layer place, then etch ultra-thin copper foil layer and expose first circuit layer, hinder to weld and the surface coating is handled first circuit layer at last.

However, in the prior art, the seed layer is a laminated copper foil or a copper-deposited layer, and the bonding force between the seed layer and the dielectric layer is poor compared with the bonding force between the sputtered seed layer and the dielectric layer. Secondly, the way that the copper post need be used laser processing to switch on between the circuit has following not enough: a: the laser drilling machining precision is poor relative to the graphical imaging processing of photoresist, and the laser machining cannot manufacture high-level fine paths (generally, the laser precision is 10um level, and the graphical photoetching precision is within 3 um); b: the copper columns obtained by laser drilling are large at the top and small at the bottom, and relative to the copper columns electroplated by the patterns and regular at the top and bottom, the stability and the thermal conductivity of the related electric signals are poor; c: the laser aperture is large at the top and small at the bottom, and the large aperture limits the spacing of fine lines; d: laser machining of copper pillars on a substrate can be time consuming. And thirdly, when the copper foil of the first circuit layer is etched in a board-by-board mode, the copper foil and the circuit layer are integrated without protection, the circuit layer has the risk of being etched, and the uniformity of the circuit layer is difficult to control. Finally, the prior art has long process flow, complex process and high manufacturing and processing cost.

Disclosure of Invention

Embodiments of the present invention are directed to providing a method of manufacturing an ultra-thin substrate structure to solve the above technical problems. According to the invention, the sputtered seed titanium layer is arranged at the lower side of the first wiring layer, so that the first wiring layer can be well protected when the metal layer is etched and separated, and the wiring layer has higher controllability; the through hole column is manufactured by a copper column method, the upper and lower sizes of the through hole column are consistent, and the through hole column has higher electric signal reliability and better heat conductivity; the metal seed layer is manufactured in a sputtering mode, and the bonding force between the wiring layer and the dielectric layer is better, so that the reliability is higher; the wiring layer and the conduction column are manufactured by adopting pattern electroplating, the width, the distance and the height of the wiring layer are more controllable, and the uniformity is good; and the manufacturing process is greatly reduced, the production efficiency is improved, and the manufacturing cost is reduced.

The invention relates to a manufacturing method of an ultrathin substrate structure, which comprises the following steps:

(a) preparing a bearing plate, forming a first solder mask layer on the surface of the bearing plate, and forming a first solder mask windowing in the first solder mask layer;

(b) forming a first metal seed layer on the first solder resist layer, forming a first wiring layer on the first metal seed layer, a first via post layer on the first wiring layer, a first dielectric layer covering the first wiring layer and the first via post layer, and a second wiring layer on the first dielectric layer, wherein the first wiring layer and the second wiring layer are conductively connected through the first via post layer;

(c) forming a second solder mask layer on the second wiring layer, and forming a second solder mask windowing window in the second solder mask layer;

(d) and removing the bearing plate.

In some embodiments, wherein the carrier plate comprises a support layer and a metal foil on at least one surface of the support layer.

In some embodiments, wherein the copper foil is a double-layer metal foil, and the double-layer metal foil is attached together by physical pressing.

In some embodiments, wherein the copper foil is a single layer of metal foil with a release layer between the support layer and the single layer of metal foil.

In some embodiments, wherein the support layer comprises a prepreg layer.

In some embodiments, wherein the release layer comprises a heat removable foam adhesive layer.

In some embodiments, wherein the metal foil comprises copper, aluminum, or nickel.

In some embodiments, wherein the first metal seed layer comprises titanium, copper, a titanium tungsten alloy, or a combination thereof.

In some embodiments, wherein the first metal seed layer comprises a titanium layer and a copper layer on the titanium layer.

In some embodiments, wherein the titanium layer has a thickness of 0.1 to 0.3 μm and the copper layer has a thickness of 0.8 to 2.0 μm.

In some embodiments, wherein the titanium layer is 0.1 μm thick, the copper layer is 1.0 μm thick.

In some embodiments, wherein the height of the first via post layer is 15-30 μm.

In some embodiments, wherein the thickness of the first dielectric layer is 15-30 μm.

In some embodiments, wherein the thickness of the first wiring layer and the second wiring layer is 8-15 μm.

In some embodiments, wherein step (b) comprises:

(b1) applying a first metal seed layer on the first solder mask layer;

(b2) applying a first photoresist layer on the first metal seed layer, and patterning the first photoresist layer to form a first characteristic pattern;

(b3) electroplating the first characteristic pattern to form a first wiring layer;

(b4) applying a second photoresist layer outside the first wiring layer, and patterning the second photoresist layer to form a second feature pattern;

(b5) electroplating the second characteristic pattern to form a first through hole column layer;

(b6) removing the first photoresist layer and the second photoresist layer, and etching away the exposed first metal seed layer;

(b7) laminating a dielectric material to form a first dielectric layer, and thinning the first dielectric layer to expose the end part of the first through hole column layer;

(b8) applying a second metal seed layer on the first dielectric layer exposing the end of the first via post layer;

(b9) applying a third photoresist layer on the second metal seed layer, and patterning the third photoresist layer to form a third feature pattern;

(b10) electroplating the third characteristic pattern to form a second wiring layer;

(b11) and removing the third photoresist layer, and etching away the exposed second metal seed layer.

In some embodiments, step (b7) comprises thinning the first dielectric layer entirely by way of lapping or plasma etching to expose an end portion of the first via post layer.

In some embodiments, step (b7) comprises locally thinning the first dielectric layer by laser machining or drilling or by exposure development to expose an end of the first via post layer.

In some embodiments, wherein step (d) further comprises removing the metal foil on the first solder resist layer by etching after removing the carrier board by separating the support layer and the metal foil.

In some embodiments, wherein step (b) comprises:

(b 1') applying a first metal seed layer on the first solder mask layer;

(b 2') applying a first photoresist layer on the first metal seed layer and patterning the first photoresist layer to form a first feature pattern;

(b 3') electroplating the first feature pattern to form a first wiring layer;

(b 4') removing the first photoresist layer, etching away the exposed first metal seed layer;

(b 5') laminating a dielectric material on the first wiring layer to form a first dielectric layer;

(b 6') forming a first via in the first dielectric layer and applying a second metal seed layer on the first dielectric layer;

(b 7') applying a third photoresist layer on the second metal seed layer, patterning the third photoresist layer to form a third feature pattern exposing the first via;

(b 8') electroplating the third feature pattern while forming a first via post layer and a second wiring layer;

(b 9') removing the third photoresist layer and etching away the exposed second metal seed layer.

In some embodiments, wherein said step (c) further comprises: and continuously adding a third wiring layer formed on a second dielectric layer on the second wiring layer, forming a second solder mask layer on the third wiring layer, and forming a second solder mask windowing window in the second solder mask layer.

Drawings

For a better understanding of the invention and to show embodiments thereof, reference is made to the accompanying drawings, purely by way of example.

With specific reference to the drawings, it must be emphasized that the specific illustrations are exemplary and are merely intended to illustratively discuss a preferred embodiment of the invention, and are presented in order to provide what is believed to be the most useful and readily understood illustration of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention; those skilled in the art will recognize how the several forms of the present invention may be embodied in practice with reference to the description of the figures. In the drawings:

FIGS. 1(a) to 1(m) show schematic cross-sectional views of intermediate structures obtained by the process of the present invention.

Detailed Description

First embodiment

The first embodiment of the method for manufacturing an ultra-thin substrate structure includes the steps of: the carrier plate 101 is prepared-step (a), as shown in FIG. 1 (a). The carrier plate 101 may comprise a support layer 1011 and a metal foil on at least one surface of the support layer 1011. In general, the metal foil may be a double-layer metal foil formed by attaching a first metal foil 1012 and a second metal foil 1013 together through physical pressing, the first metal foil 1012 is located on the first surface of the support layer 1011, and the second metal foil 1013 is located on the surface of the first metal foil 1012, and the subsequent removal of the carrier plate 101 may be achieved by separating the first metal foil 1012 and the second metal foil 1013, and then etching the second metal foil 1013. The metal foil may also be a single-layer metal foil, and a release layer is disposed between the support layer 1011 and the single-layer metal foil, the release layer may include a foaming adhesive layer that can be removed by heating, the foaming adhesive layer is made of a temperature-sensitive material, and the substrate may be heated to a specific temperature to separate the foaming adhesive layer from the single-layer metal foil when the carrier board 101 is subsequently removed, and then the single-layer metal foil is etched. The carrier plate 101 may further comprise a third metal foil 1014 on the second surface of the support layer 1011. In general, the support layer 1011 may include a prepreg layer; the metal foil may comprise copper, aluminium or nickel, preferably copper.

Generally, the thickness of each layer of the carrier plate 101 can be set according to actual requirements, so as to provide sufficient support strength for the ultra-thin substrate structure; preferably, the first metal foil 1012 is a 3 μm copper foil, the second metal foil 1013 is an 18 μm copper foil, the third metal foil 1014 is an 18 μm copper foil, and the support layer is 145 μm polypropylene.

Next, a first solder mask layer 102 is formed on the surface of the carrier board 101, and a first solder mask opening window 1021 is formed in the first solder mask layer 102 — step (b), as shown in fig. 1 (b). The first solder resist layer 102 is formed by applying a solder resist material on the surface of the second metal foil 1013, the solder resist material may be a photosensitive dielectric material, such as green oil or PID material, and the like, and is not limited specifically; but may also be a non-photosensitive dielectric material. When the solder mask material is a photosensitive dielectric material, a first solder mask opening window 1021 can be formed in the first solder mask layer 102 in an exposure and development mode; when the solder resist material is a non-photosensitive dielectric material, the first solder resist opening window 1021 can be formed in the first solder resist layer 102 by laser machining or drilling. The thickness of the first solder resist layer may be 5-15 μm.

Then, a first metal seed layer 1031 is applied on the first solder resist layer 102, a first photoresist layer 1032 is applied on the first metal seed layer 1031 and the first photoresist layer 1032 is patterned to form a first feature pattern, and the first feature pattern is plated to form a first wiring layer 1033 — step (c), as shown in fig. 1 (c). Typically, a first metal seed layer 1031 may be applied on the first solder resist layer 102 by electroless plating or sputtering; the first metal seed layer 1013 may include titanium, copper, titanium tungsten alloy, or a combination thereof; preferably, a first metal seed layer 1031 is applied by sputtering a titanium layer first and then sputtering a copper layer on the surface of the titanium layer; the thickness of the titanium layer can be 0.1-0.3 μm, and the thickness of the copper layer can be 0.8-2.0 μm; preferably, the thickness of the titanium layer is 0.1 μm, and the thickness of the copper layer is 1.0 μm; the titanium layer is directly adjacent to the second metal layer 1013, and in a subsequent step of etching the second metal layer 1013, the first wiring layer 1033 can be prevented from being etched by a chemical solution, so that controllability of the first wiring layer 1033 can be improved. Copper is electroplated in the first feature pattern to form a first wiring layer 1033, the first wiring layer 1033 having a thickness of 8-15 μm. The wiring layer is prepared in a pattern electroplating mode, the width and the distance of the wiring layer are controllable, and the uniformity is good.

Next, in step (c), a second photoresist layer 1034 is applied outside the first wiring layer 1033 and patterned to form a second feature pattern, and the second feature pattern is electroplated to form a first via post layer 1035 — step (d), as shown in fig. 1 (d). Typically, copper is electroplated in the second feature pattern to form a first via post layer 1035, the height of the first via post layer 1035 being 15-30 μm. The through hole column is prepared in an image electroplating mode, the upper size and the lower size of the through hole column are consistent, and the through hole column has higher electric signal reliability and better heat conductivity.

Then, the first photoresist layer 1032 and the second photoresist layer 1034 are removed, the exposed first metal seed layer 1031 is etched away, the dielectric material is laminated to form the first dielectric layer 103, and the first dielectric layer 103 is thinned to expose the end portion of the first via post layer 1035, step (e), as shown in fig. 1 (e). In general, the dielectric material may include an organic dielectric material, an inorganic dielectric material, or a combination thereof; preferably, the dielectric material comprises polyimide, epoxy, bismaleimide, triazine resin, ceramic filler, glass fiber, or combinations thereof; the dielectric material includes photosensitive dielectric material and non-photosensitive dielectric material according to the functional requirement. When the dielectric material is a non-photosensitive dielectric material, the first dielectric layer 103 may be thinned entirely by plate grinding or plasma etching to expose the end of the first via post layer 1035, or the first dielectric layer 103 may be thinned locally by laser machining or drilling to expose the end of the first via post layer 1035; when the dielectric material is a photosensitive dielectric material, the first dielectric layer 103 may be locally thinned by exposure and development to expose the end of the first via post layer 1035.

Next, a second metal seed layer 1036 is applied over the first dielectric layer 103; applying a third photoresist layer on the second metal seed layer 1036 and patterning the third photoresist layer to form a third feature pattern; electroplating the third feature pattern to form a second wiring layer 1038; the third photoresist layer is removed and the exposed second metal seed layer 1036 is etched away, step (f), as shown in fig. 1 (f). Typically, a second metal seed layer 1036 may be applied over the first dielectric layer 103 by electroless plating or sputtering; the second metal seed layer 1036 may comprise titanium, copper, titanium tungsten alloy, or a combination thereof; preferably, the second metal seed layer 1036 is applied by first sputtering a 0.1 μm titanium layer and then sputtering a 1 μm copper layer on the surface of the titanium layer; by forming the second metal seed layer 1036 by sputtering, the second wiring layer 1038 and the first dielectric layer 103 have better bonding strength and higher reliability. The second wiring layer 1038 is formed by electroplating copper in the third feature pattern, and the thickness of the second wiring layer 1038 is 8 to 15 μm. The second wiring layer 1038 and the first wiring layer 1033 are conductively connected through the first via post layer 1035.

Then, a second solder resist layer 104 is formed on the second wiring layer 1038, and a second solder resist opening window 1041 is formed in the second solder resist layer 104 — step (g), as shown in fig. 1 (g). The second solder resist layer 104 is formed by applying a solder resist material on the second wiring layer 1038. When the solder resist material is a photosensitive dielectric material, a second solder resist opening window 1041 may be formed in the second solder resist layer 104 by exposure and development; when the solder resist material is a non-photosensitive dielectric material, the second solder resist opening window 1041 may be formed in the second solder resist layer 104 by laser processing or drilling. After the second solder resist opening window 1041 is formed, a metal surface treatment may be performed on the exposed second wiring layer 1038 by applying nickel palladium gold or an organic solder resist film. The thickness of the second solder resist layer is 5-15 μm.

Next, the carrier 101 is removed to obtain the ultra-thin substrate structure 100, step (h), as shown in fig. 1 (h). Generally, the loading plate 101 may be removed by separating the first metal foil 1012 and the second metal foil 1013 and then etching the second metal foil 1013.

Second embodiment

The second embodiment of the method for manufacturing an ultra-thin substrate structure includes steps (a) - (c) as described in the first embodiment, and will not be described again.

Then, step (c) is performed, the first photoresist layer 1032 is removed, the exposed first metal seed layer 1031 is etched away, and a dielectric material is laminated on the first wiring layer 1033 to form a first dielectric layer 103, as shown in fig. 1 (i). Typically, the thickness of the first dielectric layer 103 is 15-30 μm.

Next, a first via 1039 is formed in the first dielectric layer 103 and a second metal seed layer 1036 is applied over the first dielectric layer 103, step (j), as shown in fig. 1 (j). When the dielectric material is a non-photosensitive dielectric material, the dielectric material may be locally thinned by laser processing or drilling to form a first via 1039 in the first dielectric layer 103; when the dielectric material is a photosensitive dielectric material, the first via 1039 can be formed in the first dielectric layer 103 by partially thinning the dielectric material by exposure and development.

Then, a third photoresist layer is applied on the second metal seed layer 1036 and patterned to form a third feature pattern exposing the first via 1039; electroplating the third feature pattern while forming the first via post layer 1035 and the second wiring layer 1038; the second photoresist layer is removed and the exposed second metal seed layer 1036 is etched away. Step (k), as shown in FIG. 1 (k). Typically, the first via post layer 1035 and the second wiring layer 1038 are formed by electroplating copper in the third feature pattern, the height of the first via post layer 1035 is 15-30 μm, and the thickness of the second wiring layer 1038 is 8-15 μm. The second wiring layer 1038 and the first wiring layer 1033 are conductively connected through the first via post layer 1035.

Next, a second solder resist layer 104 is formed on the second wiring layer 1038, and a second solder resist opening window 1041 is formed in the second solder resist layer 104 — step (l), as shown in fig. 1 (l).

Then, the carrier 101 is removed, and the ultra-thin substrate structure 200 is obtained, step (m), as shown in fig. 1 (m).

In addition, the above structure is only an example of a process for demonstrating the structure of the ultra-thin substrate, the structure is not limited to 2 layers, and a third wiring layer formed on the second dielectric layer may be further added on the second wiring layer 1038 according to actual needs, a second solder mask layer is formed on the third wiring layer, and a second solder mask opening window is formed in the second solder mask layer.

Those skilled in the art will recognize that the present invention is not limited to what has been particularly shown and described hereinabove and hereinbelow. Rather, the scope of the present invention is defined by the appended claims, including both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description.

In the claims, the terms "comprise" and variations such as "comprises," "comprising," and the like, mean that the recited elements are included, but generally not the exclusion of other elements.