A method for manufacturing a solder mask layer of a packaging substrate and a packaging substrate

Abstract

The present invention provides a method for manufacturing a solder resist layer of a packaging substrate and the solder resist layer of the packaging substrate, the manufacturing method comprising: providing a packaging substrate; pre-processing the packaging substrate; vacuum laminating the pre-processed packaging substrate so that the solder resist film made of solder resist ink is tightly combined with the packaging substrate; exposing a preset area of ​​the solder resist film to obtain a first solder resist layer; developing the first solder resist layer to remove the unexposed portion thereof to obtain a second solder resist layer; pre-baking the second solder resist layer before curing so that the solder resist ink forming the second solder resist layer is heated and flows to obtain a third solder resist layer; the surface area of ​​the third solder resist layer is greater than the surface area of ​​the second solder resist layer; curing the third solder resist layer to obtain the solder resist layer of the packaging substrate. Aiming at the problem of side erosion during development, the present invention adds a pre-baking step before curing between the development and curing steps, which can effectively reduce the side erosion amount of the final solder resist layer.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor processing, and in particular relates to a method for manufacturing a solder resist layer of a packaging substrate and a packaging substrate. Background Art

[0002] The solder resist ink is applied to the circuit board to form a pattern consistent with the film in the form of a film layer. The film-like solder resist ink can prevent bridging during welding, provide a long-term insulating environment and anti-chemical protection. The film-like solder resist ink is generally called a solder resist layer.

[0003] The conventional method for making solder mask is: pre-treatment → lamination → exposure → development → curing. However, due to the increasing packaging density and packaging precision of substrates, the pad size and line width of substrates are getting smaller and smaller. Correspondingly, the requirements for the alignment precision and window size of solder mask development openings are getting higher and higher. This poses a great challenge to the conventional method for making solder mask. For example, if the post-curing treatment is directly performed after the development step, the side erosion parts that appear in the development step will also be directly shaped, thereby increasing the probability that the subsequent finished package substrate will be defective. Summary of the invention

[0004] In view of the above-mentioned problems existing in the existing circuit board processing technology, the main purpose of the present invention is to provide a method for manufacturing a solder mask layer of a packaging substrate and a packaging substrate. The provided method for manufacturing a solder mask layer of a packaging substrate addresses the problem of side etching during development, and a pre-baking step before curing is added between the development and curing steps, which can effectively reduce the amount of side etching of the final solder mask layer.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for manufacturing a solder resist layer of a packaging substrate, comprising the following steps:

[0007] Providing a packaging substrate;

[0008] Pre-processing the packaging substrate;

[0009] Performing vacuum lamination on the pre-treated packaging substrate so that the solder resist film made of solder resist ink is tightly combined with the packaging substrate;

[0010] Exposing a preset area of ​​the solder resist film to obtain a first solder resist layer;

[0011] Developing the first solder resist layer to remove the unexposed portion thereof to obtain a second solder resist layer;

[0012] Pre-baking the second solder resist layer before curing, so that the solder resist ink of the second solder resist layer flows under the heat, so as to obtain a third solder resist layer; the surface area of ​​the third solder resist layer is larger than the surface area of ​​the second solder resist layer;

[0013] The third solder resist layer is cured to obtain the package substrate solder resist layer.

[0014] As a further description of the above technical solution, in the step of "pre-baking the second solder resist layer before curing, so that the solder resist ink of the second solder resist layer flows when heated to obtain a third solder resist layer", the pre-baking temperature before curing is 100°C-150°C, and the pre-baking time before curing is 10min-20min.

[0015] As a further description of the above technical solution, in the step of "vacuum laminating the pre-treated packaging substrate to ensure a tight bond between the solder resist film made of solder resist ink and the packaging substrate", a vacuum laminating machine is used to vacuum hot-press the solder resist film.

[0016] As a further description of the above technical solution, in the step of "curing the third solder resist layer to obtain the package substrate solder resist layer", the curing includes sequentially performing first photocuring, thermal curing and second photocuring on the fourth solder resist layer.

[0017] As a further description of the above technical solution, the first light curing and the second light curing both use LED cold light UV machine;

[0018] The thermal curing is carried out in an oven or a hot air furnace.

[0019] The present invention also provides a packaging substrate, comprising a packaging substrate solder resist layer manufactured by the manufacturing method of the packaging substrate solder resist layer as described above.

[0020] By means of the above technical solution, the outstanding effects of the present invention are:

[0021] When the method for manufacturing a solder resist layer of a package substrate provided by the present invention is used to manufacture the solder resist layer of a package substrate, after the second solder resist layer is obtained by development, it is pre-baked before curing, so that the solder resist ink forming the second solder resist layer flows toward its periphery under the heat to obtain the third solder resist layer; therefore, the third solder resist layer having a larger outer surface area than the second solder resist layer can effectively cover the part where the side corrosion occurs during development from the edge, and the side corrosion amount of the solder resist layer of the package substrate formed after curing is effectively reduced;

[0022] In the manufacturing method of the solder mask layer of the packaging substrate provided by the present invention, the parameter setting of the pre-baking temperature and time before curing ensures that the third solder mask layer effectively covers the parts where side etching occurs during development from the edge, while avoiding the situation where the third solder mask layer excessively covers the board surface where no side etching occurs during development, resulting in insufficient development in the end. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The invention discloses a method for manufacturing a solder resist layer of a packaging substrate, comprising the following steps:

[0025] Providing a packaging substrate;

[0026] Pre-processing the packaging substrate;

[0027] Performing vacuum lamination on the pre-treated packaging substrate so that the solder resist film made of solder resist ink is tightly combined with the packaging substrate;

[0028] Exposing a preset area of ​​the solder resist film to obtain a first solder resist layer;

[0029] Developing the first solder resist layer to remove the unexposed portion thereof to obtain a second solder resist layer;

[0030] Pre-baking the second solder resist layer before curing, so that the solder resist ink of the second solder resist layer flows under the heat, so as to obtain a third solder resist layer; the surface area of ​​the third solder resist layer is larger than the surface area of ​​the second solder resist layer;

[0031] The third solder resist layer is cured to obtain the package substrate solder resist layer.

[0032] By means of the above method, first, the provided packaging substrate is pre-treated to clean and roughen the board surface so as to subsequently enhance the bonding strength between the board surface and the solder resist film; then, the pre-treated packaging substrate can be vacuum pressed to make the solder resist film made of solder resist ink tightly bonded to the packaging substrate; then, a preset area of ​​the solder resist film is exposed to obtain a first solder resist layer; then, the first solder resist layer is developed to remove the unexposed portion thereof, but in this step, due to the dense circuit graphics, even if various parameters are strictly controlled, there will still be side etching due to development; therefore, before curing it, a pre-curing pre-bake is also performed to make the solder resist ink of the second solder resist layer flow under the heat. In this step, the surface area of ​​the second solder resist layer gradually increases, so as to slowly cover the part where the side erosion occurs on its edge. After the step is completed, the second solder resist layer becomes the third solder resist layer. Compared with the second solder resist layer, the surface area of ​​the third solder resist layer is slightly larger than that of the second solder resist layer. Since the amount of solder resist ink is the same, the thickness of the third solder resist layer is slightly smaller than that of the second solder resist layer. It should be understood that the difference in thickness between the second solder resist layer and the third solder resist layer formed in this step needs to be designed according to the type of solder resist ink used in actual production, the size of the side erosion part and its qualified parameter requirements, so that the package substrate solder resist layer obtained by curing the third solder resist layer meets the preset requirements. As a result, the side erosion amount of the package substrate solder resist layer finally formed after curing is effectively reduced, thereby reducing the probability that the subsequent finished package substrate is a defective product.

[0033] One embodiment includes the following steps:

[0034] First, a packaging substrate is provided;

[0035] Secondly, the packaging substrate is pre-processed; more specifically, a specific physical and / or chemical method is first used to clean and roughen the surface of the packaging substrate so as to subsequently enhance the bonding strength between the surface and the solder resist film.

[0036] Next, a solder resist film is applied to the pre-treated packaging substrate. More specifically, a vacuum laminator is used to vacuum and hot-press the solder resist film made of solder resist ink onto the surface of the packaging substrate, and make it tightly bonded to the packaging substrate.

[0037] Then, an exposure film designed according to actual needs is attached to the solder mask, and a preset area of ​​the solder mask is exposed under ultraviolet light to obtain a first solder mask layer with a solder mask pattern. In this step, the preset area irradiated by ultraviolet rays (i.e., the area without shading) will be cured and finally retained through subsequent processing steps, while the part other than the preset area will be removed in subsequent steps.

[0038] Subsequently, developing the first solder resist layer with a developer to remove the unexposed portion except for a preset area to obtain a second solder resist layer;

[0039] Then, the second solder resist layer is pre-baked before curing. In this step, the temperature is maintained at 125°C to heat the second solder resist layer for 15 minutes, so that the solder resist ink constituting the second solder resist layer flows due to heat. The flowing solder resist ink starts to cover the developing side erosion part from the outer edge of the developing side erosion, gradually reducing the area of ​​the developing side erosion effectively, and avoiding the excessive coverage of the board surface where the developing side erosion does not occur, resulting in insufficient development. After this step, the second solder resist layer becomes the third solder resist layer. Looking up or down at the second solder resist layer and the third solder resist layer, the outer surface area of ​​the third solder resist layer is larger than that of the second solder resist layer, which is equivalent to the third solder resist layer being formed by the overall widening of the solder resist ink of the second solder resist layer due to the flow of the solder resist ink. At the same time, it should be understood that since the amount of solder resist ink is certain, the thickness of the third solder resist layer is slightly smaller than that of the second solder resist layer, and the thickness direction is perpendicular to the direction of the package substrate. Of course, in other embodiments, the heating temperature parameter of this step can be selected as other values ​​between 100°C and 150°C, and the heating time can be selected as other values ​​between 10min and 20min, based on the thickness difference between the second solder resist layer and the third solder resist layer formed in this step, the type of solder resist ink used in actual production, the size of the side erosion part and its qualified parameter requirements, etc.

[0040] Finally, the third solder resist layer is cured to obtain the package substrate solder resist layer with effectively reduced development side erosion. In this step, the curing includes first light curing, heat curing and second light curing of the third solder resist layer in sequence, and the three curings are performed in sequence to ensure that the third solder resist layer can be fully cured into the package substrate solder resist layer. Among them, the first light curing and the second light curing are both performed using an LED cold light UV machine; the heat curing is performed using an oven. Of course, in other embodiments, a hot air furnace can also be used to heat cure the third solder resist layer.

[0041] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any changes, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a solder mask layer of a package substrate, characterized in that: The following steps are involved: Providing a packaging substrate; Pre-processing the packaging substrate; Performing vacuum lamination on the pre-treated packaging substrate so that the solder resist film made of solder resist ink is tightly combined with the packaging substrate; Exposing a preset area of ​​the solder resist film to obtain a first solder resist layer; Developing the first solder resist layer to remove the unexposed portion thereof to obtain a second solder resist layer; Pre-baking the second solder resist layer before curing, so that the solder resist ink forming the second solder resist layer is heated and flows, so as to obtain a third solder resist layer; the surface area of ​​the third solder resist layer is larger than the surface area of ​​the second solder resist layer, so as to cover the part where the side erosion occurs at the edge of the second solder resist layer; the pre-baking temperature before curing is 100° C.-150° C., and the pre-baking time before curing is 10 min-20 min; The third solder resist layer is cured to obtain the package substrate solder resist layer; the curing includes sequentially performing first light curing, heat curing and second light curing on the third solder resist layer; the first light curing and the second light curing are both performed using an LED cold light UV machine; the heat curing is performed using an oven or a hot air furnace.

2. The method for manufacturing a solder resist layer of a package substrate according to claim 1, characterized in that: In the step of "vacuum laminating the pre-treated packaging substrate so that the solder resist film made of solder resist ink and the packaging substrate are tightly bonded", a vacuum laminating machine is used to vacuum hot-press the solder resist film.

3. A packaging substrate, characterized in that: It comprises a packaging substrate solder resist layer manufactured by the manufacturing method of the packaging substrate solder resist layer according to any one of claims 1-2.