JP-7856031-B2 - Circuit board manufacturing method

Inventors

• 佐藤 亮太
• 依田 正応

Assignees

• 味の素株式会社

Dates

Publication Date

20260511

Application Date

20230322

Claims (10)

1. (I) A step of laminating a resin sheet, which comprises a support and a resin composition layer provided on the support having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less, onto a substrate such that the resin composition layer is bonded to the substrate. (II) A step of forming an insulating layer by thermal curing the resin composition layer, and (III) A step of peeling off the support, A method for manufacturing a circuit board, comprising the following in this order: The water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% using a method compliant with JIS K7129, is 0.5 g/ m² · mm⁻¹ ·1.24h or less. A method comprising, in step (II), subjecting the resin composition layer to a heat treatment in which it is held at a temperature T1, and then to a heat treatment in which it is held at a temperature T2 that is higher than the temperature T1.
2. The method according to claim 1, wherein the temperature T2 is 150°C or higher.
3. The method according to claim 1, wherein the difference between temperatures T1 and T2, T2-T1, is 20°C or more.
4. The method according to claim 1, wherein the temperature T1 is 50°C or higher.
5. The method according to claim 1, wherein in step (II), the resin composition layer is heated to a temperature T2 at a heating rate of 0.5°C/min or more and 30°C/min or less.
6. The method according to claim 1, wherein the resin composition layer comprises a thermosetting resin.
7. The method according to claim 1, wherein the resin composition layer contains one or more curing agents selected from the group consisting of active ester-based curing agents, phenol-based curing agents, naphthol-based curing agents, and carbodiimide-based curing agents.
8. The method according to claim 1, further comprising the step of forming via holes in an insulating layer with a laser.
9. The method according to any one of claims 1 to 8, further comprising the step of forming a conductive layer on the surface of an insulating layer.
10. The method according to claim 9, wherein the peel strength between the insulating layer and the conductor layer is 0.3 kgf/cm or more.

Description

This invention relates to a method for manufacturing a circuit board. Thermosetting resins and resin compositions containing their curing agents have been widely used as insulating materials for circuit boards such as printed circuit boards and redistribution boards for semiconductor packages, due to their excellent insulating properties, heat resistance, and adhesion. On the other hand, with the recent increase in communication speeds, insulating materials for circuit boards require insulating materials with excellent dielectric properties (low dielectric loss tangent) to reduce transmission loss when operating in high-frequency environments. Furthermore, insulating materials exhibiting a low coefficient of thermal expansion are required to suppress cracks and circuit distortion caused by differences in thermal expansion between the insulating layer and the conductor layer in circuit boards, or to suppress warping when forming large-area insulating layers in the manufacturing of circuit boards such as wafer-level packages (WLPs) and panel-level packages (PLPs). As insulating materials exhibiting both good dielectric properties and a low coefficient of thermal expansion, resin compositions with a high proportion of inorganic fillers such as silica particles are known (for example, Patent Document 1). Japanese Patent Publication No. 2022-93188 Before describing in detail the manufacturing method of the circuit board of the present invention, the resin sheet used in the manufacturing method will be explained. <Resin sheet> The present invention provides a method for manufacturing a circuit board, which involves using a resin sheet comprising a support and a resin composition layer provided on the support, the resin sheet having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less. The resin sheet is characterized in that the water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% in accordance with JIS K7129, is 0.5 g/ m² · mm⁻¹ ·24h or less. The following describes preferred embodiments from the viewpoint of more effectively enjoying the effects of the present invention. -Support- The inventors have found that even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, it is important to use a resin sheet equipped with a support having a water vapor permeability coefficient of a certain value or less in order to obtain an insulating layer with good adhesion to the conductor layer. More specifically, it is important that the water vapor transmission coefficient of the support (g/m²· mm⁻¹ ·24h), calculated by multiplying the water vapor transmission rate of the support (g/m²· mm⁻¹ ·24h), measured under conditions of 40 ° C and a relative humidity difference of 90% using a method compliant with JIS K7129, by the thickness of the support (mm), is 0.5 g/ m² · mm⁻¹ ·24h or less. Even when forming an insulating layer using a resin composition layer with a high inorganic filler content and a thickness of 15 μm or less, from the viewpoint of providing an insulating layer with even better adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer exhibiting low surface roughness after roughening treatment (desmear treatment), the water vapor permeability coefficient of the above support is preferably 0.45 g/ m² ·mm -1.24h or less, more preferably 0.4 g/ m² ·mm -1.24h or less, even more preferably 0.35 g/ m² ·mm -1.24h or less, 0.3 g/ m² ·mm -1.24h or less, 0.28 g/ m² ·mm -1.24h or less, 0.26 g/ m² ·mm -1.24h or less, 0.24 g/ m² ·mm -1.24h or less, 0.22 g/ m² ·mm -1.24h or less, or 0.2 g/ m² ·mm It is -1.24h or less. The lower limit of the water vapor permeability coefficient is not particularly limited and may be, for example, 0.05 g/ m² ·mm -1.24h or more, 0.06 g/ m² ·mm -1.24h or more, 0.08 g/ m² ·mm -1.24h or more, 0.1 g/ m² ·mm -1.24h or more, etc. Examples of supports that satisfy such water vapor permeability coefficients include: (1) a base film having a water vapor permeability coefficient of 0.5 g/ m² · mm⁻¹⁰⁴h or less; (2) a base film with a release layer that exhibits an overall water vapor permeability coefficient of 0.5 g/ m² · mm⁻¹⁰⁴h or less by providing a release layer on the base film; (3) a base film with a barrier layer that exhibits an overall water vapor permeability coefficient of 0.5 g/ m² · mm⁻¹⁰⁴h or less by providing a barrier layer on the base film; and (4) a support having a layer configuration of a release layer/base film/barrier layer that exhibits an overall water vapor permeability coefficient of 0.5 g/ m² · mm⁻¹⁰⁴h or less by providing a barrier layer on the side of the base film with a release layer opposite to the release layer. Examples of base films used as support materials include thermoplastic re