Method for manufacturing embedded printed circuit board

Abstract

A method for manufacturingan embedded printed circuit board, according to the present invention, includes: a cavity body formation step for forming a cavity body (10) by precuring and bonding a film (2) comprising an insulating resin on one surface of a core material (1) to form a cavity (3); a component mounting step for forming a component-mounted body (9) by fixing an electronic component (7) on a first conductive layer (4) disposed on a support body (5); a layup step for stacking the component-mounted body (9), the cavity body (10), an insulating layer (11), and a second conductive layer (12); and a board formation step for fully curing the film (2) and the insulating layer (11) and performing lamination pressing.

Description

Method for manufacturing a component-embedded substrate

[0007] ,

[0001] The present invention relates to a method for manufacturing a component-embedded substrate.

[0002] A component-embedded substrate in which electronic components such as electronic devices are embedded in a substrate is known (see, for example, Patent Document 1). In Patent Document 1, the volume for embedding components is reduced to embed components with high reliability. In the method for manufacturing a component-embedded substrate represented by Patent Document 1, a cavity for accommodating components is provided only in a core material, and then this cavity is filled with resin by lamination pressing. At this time, the position of the electronic component is fixed with a temporary tape such as a resin film.

[0003] Japanese Patent Application Laid-Open No. 2019-528537

[0004] However, during lamination pressing, since the position of the electronic component is held only by the adhesiveness of the temporary tape, when the resin flows into the cavity during lamination pressing, even if the amount of this resin is reduced, it may be difficult to surely hold the position of the electronic component.

[0005] If the electronic component is fixed on the support in advance, such displacement of the electronic component does not occur, but it is also necessary to form a cavity in the insulating resin for flowing into the cavity (especially under the electronic component) during lamination pressing. However, it is not possible to drill holes in the insulating resin that forms the insulating layer alone, and such a manufacturing method has not been realized.

[0006] The present invention is considered in view of the above prior art, and an object thereof is to provide a method for manufacturing a component-embedded substrate capable of surely holding the position of an electronic component in a cavity during lamination pressing.

[0007] To achieve the above objective, the present invention provides a method for manufacturing a component-embedded substrate, comprising: a cavity body forming step of forming a cavity body by melting and pre-curing a film made of insulating resin to one surface of a substantially flat core material to form a cavity which is a through-hole in which an electronic component is to be housed; a component mounting step of fixing and mounting the electronic component on a first conductive layer arranged on a support to form a component mounting body; a layup step of stacking the component mounting body, the cavity body, an insulating layer, and a second conductive layer after the cavity forming step and the component mounting step; and a substrate forming step of fully curing the film and the insulating layer and performing a lamination press.

[0008] According to the present invention, since the lamination press is performed with the electronic components already mounted on the support, the electronic components will not shift position even if resin flows into the cavity. Since the cavity through which the electronic components are inserted during the layup process is made in the core material and the film integrated therewith, the film flowing beneath the electronic components during the lamination press can also be perforated. At this time, since the film is bonded to the core material by pre-curing, the film will not shift during the perforation process, nor will it shift during the lamination press.

[0009] This is a flowchart of the manufacturing method for a component-embedded substrate according to the present invention. This is a schematic cross-sectional view of the core material. This is a schematic cross-sectional view when a film is bonded to the core material. This is a graph showing the relationship between temperature and viscosity for the insulating resin. This is a schematic cross-sectional view of the cavity. This is a schematic diagram showing the layup state. This is a schematic diagram of a component-embedded substrate.

[0010] The method for manufacturing a component-embedded substrate according to the present invention is carried out according to the flowchart shown in Figure 1. First, a cavity formation process is performed (step S1). This process involves melting and pre-curing a film 2 made of insulating resin to one surface of a substantially flat core material 1 to bond it, thereby forming a cavity 3, which is a through-hole in which an electronic component 7 is to be housed, and forming a cavity body 10.

[0011] First, prepare a core 1 as shown in Figure 2. The core material 1 has a certain degree of rigidity and can be an insulating resin or a metal. Then, as shown in Figure 3, bond the film 2 to the core material 1. The film 2 does not contain glass cloth and can be any insulating resin, but for example, epoxy resin, cyanate resin, or silicone resin can be used. These resins may also contain alumina or aluminum nitride. Insulating resins made from these materials have high viscosity (high tackiness), making it difficult to drill holes in them on their own.

[0012] At this point, the film 2 is partially cured and adheres to the core material 1. As shown in Figure 4, when the insulating resin is heated to a certain temperature, its melt viscosity decreases and it melts (80°C to 150°C in Figure 4). Then, as it cools, its melt viscosity increases, and at this point, the film 2 becomes tacky and adheres to the core material 1. Further cooling causes it to harden again and adhere to the core material 1. This process of heating the insulating resin to its melt viscosity and then cooling and curing it is called partial curing.

[0013] Then, as shown in Figure 5, a cavity 3, which is a through-hole that penetrates the core material 1 and the film 2, is formed. In this way, the cavity body 10 is formed.

[0014] Next, the component mounting process is performed (step S2). This process involves fixing and mounting electronic components 7 onto the first conductive layer 4 arranged on the support 5 to form a component mounting body 9.

[0015] As shown in Figure 6, first, a support 5 having a first conductive layer 4 on one side is prepared. For example, a copper-clad laminate or a metal plate with a pattern formed on it can be used. Terminals 8 of an electronic component 7 are mounted on this first conductive layer 4 via an adhesive 6. This securely fixes the position of the electronic component 7 on the first conductive layer 4. In this way, a component mounting body 9 is formed. Note that there is no restriction on the order in which the cavity formation process and the component mounting process are performed; they may be performed separately or simultaneously.

[0016] Next, a layup process is performed (step S3). This process involves stacking the component mounting body 9, the cavity body 10, the insulating layer 11, and the second conductive layer 12 after the cavity formation process and the component mounting process.

[0017] As shown in Figure 6, a cavity body 10 is laid on top of the component mounting body 9, an insulating layer 11 is laid on top of the cavity body 10, and a second conductive layer 12 is laid on top of the insulating layer 11. The insulating layer 11 may be made of the same material as the film 2, or it may be a prepreg.

[0018] Next, the substrate formation process is performed (step S4). This process involves fully curing the film 2 and the insulating layer 11 and then performing lamination pressing.

[0019] When lamination pressing is performed, the film 2 and the insulating layer 11 melt and flow into the cavity 3, forming a component-embedded substrate 13 as shown in Figure 7. In this component-embedded substrate 13, the film 2 flows so as to cover the underside of the electronic component 7. At this time, the film 2 and the insulating layer 11 are further heated and fully cured. Full curing refers to heating the insulating resin to its melt viscosity and then heating it further to fully cure it. Therefore, full curing is performed by heating to at least 180°C as shown in Figure 4. This is because the insulating resin will start to harden again when heated above 180°C. At this time, the insulating resin is fully cured. Subsequently, vias (not shown) are formed on the component-embedded substrate 13 as needed to provide electrical connection with the first conductive layer 4. The support 5 is removed.

[0020] According to the present invention, since the lamination press is performed with the electronic components 7 already mounted on the support 5, the electronic components 7 will not shift position even if resin flows into the cavity 3. The cavity 3 through which the electronic components 7 are inserted during the layup process is made of the core material 1 and the film 2 integrated therewith, so the film 2 that flows beneath the electronic components 7 during the lamination press can also be drilled. At this time, since the film 2 is bonded to the core material 1 by pre-curing, the film 2 will not shift during the drilling process, nor will it shift during the lamination press.

[0021] This prevents misalignment of the electronic component 7 during lamination pressing and also solves the problem of perforating the film 2. In particular, because the film 2 is bonded to the core material 1 by pre-curing, it is made more fluid during lamination pressing and can flow into the cavity 3. More specifically, in order to ensure that the resin flows evenly within the cavity 3 during lamination pressing, it is necessary to arrange an insulating resin layer in the vertical direction of the cavity 3. When the electronic component 7 is fixed on the support 5, it is necessary to perforate the insulating resin layer located on the lower side of the cavity 3. Because the insulating resin layer is viscous, it was difficult to perforate it on its own, but by bonding it to the core material 1, it is possible to perforate it together with the core material 1. By using pre-curing for this bonding, the film 2 will melt even when heated in the next lamination pressing process, and can also be used as an insulating resin for substrate formation. Thus, the present invention not only allows for the bonding of the film 2 to the core material 1 and the subsequent drilling process, but also solves a problem unique to the substrate manufacturing process by employing a pre-curing method for bonding, thereby enabling its use as a fluid insulating resin during subsequent lamination pressing.

[0022] Although the method of fixing the electronic component 7 to the support 5 described above was done using adhesive 6, this method can also be applied to a flip-chip bonding structure as the component mounting body 9. In this case, the electronic component 7 is connected to the support 5 using solder paste or an alloy paste such as silver or copper as the bonding material.

[0023] 1: Core material, 2: Film, 3: Cavity, 4: First conductive layer, 5: Support, 6: Adhesive, 7: Electronic component, 8: Terminal, 9: Component mounting body, 10: Cavity body, 11: Insulating layer, 12: Second conductive layer, 13: Component embedded substrate

Claims

1. A method for manufacturing a component-embedded substrate, comprising: a cavity body forming step of forming a cavity body by melting and pre-curing a film made of insulating resin to one surface of a substantially flat core material to form a cavity which is a through-hole in which an electronic component is to be housed; a component mounting step of fixing and mounting the electronic component on a first conductive layer arranged on a support to form a component mounting body; a layup step of stacking the component mounting body, the cavity body, an insulating layer, and a second conductive layer after the cavity forming step and the component mounting step; and a substrate forming step of fully curing the film and the insulating layer and performing a lamination press.

Images