JPH0492496A - How to manufacture printed circuit boards and how to mount electronic components - Google Patents

Abstract

PURPOSE:To mount in high density by filling a conductive material in a predetermined specific through hole, electrolessly plating an entire board, and forming lands and a wiring pattern in through hole openings and on through hole marks filled with the material. CONSTITUTION:After plating catalyst such as palladium, etc., is applied to an entire board including a through hole, it is electrolessly plated to form a first layer copper-plated film 10a. A conductive material 9 is buried in a specific hole 3 by printing. It is secondly electrolessly plated to form a second layer copper-plated film 10b. A resist pattern 12 for forming a wiring pattern 1a including lands 7 is formed. With the pattern 12 as a mask the copper layer is selectively etched, and the pattern 1a including the lands 7 is formed. Further, after the pattern 12 is removed, the lands 7 necessary for connecting are removed, and the board surface is covered with solder resist 13.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of manufacturing a printed circuit board having a wiring pattern that can be mounted on both the front and back surfaces, and a method of mounting electronic components using the same, and particularly a method of manufacturing a printed circuit board suitable for high-density mounting and an electronic component using the same. Concerning how to mount parts. [Prior art 1] In the conventional printed circuit board for double-sided mounting, as shown in the cross-sectional view of FIG. It has a structure in which wiring patterns 1a are electrically connected. When mounting electronic components, those having leads 5a, such as the lead component 5, are inserted into through holes and soldered to the board by, for example, solder reflow. In addition, for chip components (also referred to as surface-mounted components) 6 that do not have leads, such as semiconductor LSIs, the wiring pattern on the surface of the board is soldered so that the connection terminals 6a of the chip components are connected to the lands 7 by paste solder. . In the through-holes around and below where the chip components 6 are mounted, chips may be embedded in advance with metal plating applied to the surface of an insulator made of the same material as the base material 2, or conductive paste may be embedded. be. Note that Japanese Patent Publication No. 61-35720 is cited as an example of this type of printed wiring board.

[Problem to be solved by the invention]

As mentioned above, when mounting components on a printed circuit board, lead components and chip components are often mounted together, and the higher the mounting density, the greater the number of through holes provided on the printed circuit board. This increases the area of the through hole in the wiring pattern.
This was causing problems in mounting chip components. In other words, when soldering the wiring pattern on the surface of the board, the chip component connects the connecting terminal 6a to the land 7 using paste solder, but at that time, if there is a through hole directly below the connection, it is filled with a conductor and need to form a stable connection. Conventional embedding methods, such as embedding metal-plated chips or embedding conductive paste into the surface of an insulator, have not been practical. That is, in the former case, the higher the density of mounting, the more difficult it is to embed the chip, and in the latter case, as seen in the terminal 6a on the left in Figure 7, the paste solder 8 sinks into the through hole 3, resulting in poor soldering. There was a problem that occurred. In any of the above methods, the chip components 6 are connected only in spots using conductive paste, and the solderability of the connections is not considered. Therefore, the purpose of the present invention is to solve these conventional problems, and its first purpose is to. In order to enable high-density packaging of lead components and chip components, the through-holes are buried using a practically improved method, and other wiring patterns are also formed on the through-holes where they are buried. Similarly, soldering is a method for manufacturing printed circuit boards that can form lands and solder chip components. The purpose is to provide each component mounting method. [Means for Solving Problems 1] The first object of the present invention is 5 (1) a step of preparing a substrate having conductive foil pasted on both sides of an insulating base material, and forming a through hole of a predetermined diameter in this substrate. (a step of providing a through hole), a step of applying a plating catalyst at least in the through hole, a step of filling a predetermined specific through hole in the through hole with a conductive material, and a step of filling the remaining through hole. A process of applying electroless plating to the entire surface of the board including the inside (through-holes that are not filled with conductive material), and lands on the openings of the through-holes and the traces of the through-holes filled with conductive material, and wiring connected to the lands. A method for manufacturing a printed circuit board, comprising the steps of forming a resist pattern for forming a pattern, selectively etching the conductive foil using the resist pattern as a mask, and removing the resist mask. This is achieved by Preferably, (2) a step of preparing a board in which conductive foil is pasted on both sides of an insulating base material, a step of providing a through hole (through hole) of a predetermined diameter in this board, and a step of providing at least a through hole in the through hole. and a step of applying a plating catalyst to. A step of performing electroless plating on the entire surface of the substrate including the inside of the through hole to form a first plating film, a step of filling a predetermined specific through hole among the through holes with a conductive material, and a step of filling the remaining through hole with a conductive material. A step of plating the entire surface of the substrate including the inside of the through hole (through hole not filled with conductive material) to form a second plating film, and a step of forming a second plating film on the through hole opening and the trace of the through hole filled with conductive material. A step of forming a resist pattern to form a land and a wiring pattern connected to the land, and selectively etching the conductive foil on which the plating film is laminated using the resist pattern as a mask to form the wiring pattern. This is achieved by a printed circuit board manufacturing method comprising the steps of forming a resist mask and removing the resist mask. More preferably, (3), instead of pasting conductive foil on both sides of the insulating base material described in (1) or (2) above, a plating film and a base material are formed on the surface of the insulating base material in a later step. This is achieved by a printed circuit board manufacturing method that includes the step of preparing a board that has been coated with an adhesive to improve its adhesion. In other words, the difference between this manufacturing method and that of (1) or (2) above is that instead of using a board with conductor foil pasted on both sides of the insulating base material, conductor plating treatment is applied in the through holes of the insulating base material. The point is that a conductor plating layer is integrally formed on both sides. Also. (4) The plating treatment in the step of forming the second plating film described in (2) or (3) above may be either electrolytic plating treatment or electroless plating treatment, but the conductor may be applied to both sides of the insulating base material. When using a substrate laminated with foil, electroless plating is practical. Furthermore, when using a substrate that is not laminated with conductive foil, electrolytic plating is faster and more practical in order to ensure the necessary thickness for the wiring conductor. Furthermore, preferably (5), after the step of removing the resist mask described in any one of (1) to (4) above, a solder resist is applied to the entire surface of the board except for the lands and through holes necessary for connecting one component. This is achieved by a printed circuit board manufacturing method that includes an additional step of forming. Practical examples of the conductive material include conductive pastes such as silver paste and copper paste because they can be easily filled into through holes. Further, as a filling method, printing is easy and desirable. Copper foil, which is commonly used as the conductor foil, is
Further, as the plating treatment, electroless copper plating treatment or electrolytic copper plating treatment is practical and preferable. Furthermore, as the solder resist, a commercially available heat-resistant resin such as epoxy resin 5 or polyimide resin is used. The second object of the present invention is as follows. (6) Following the method for manufacturing a printed circuit board described in (1) to (5) above, the lead of the lead component is placed in the through hole, and the surface is not placed on the land of the through hole filled with conductive material. Lead components and surface mounting, which includes the steps of mounting, arranging components, and respectively soldering them, are achieved by a mounting method for electronic components in which components are mixedly mounted. Preferably, (7) the above-mentioned soldering process for the components is a process in which the connection of the surface-mounted components and the connection of the lead components are divided into two stages using solders having different melting points. desirable. That is, in surface mounting, the solder for connecting the components is connected before the lead component by using a solder having a higher melting point than that of the lead component, or vice versa, but the former is preferred in practice.

[Operation 1] The specific embedding of a conductive material into a through-hole according to the present invention can be performed by immediately embedding the conductive material after the through-hole is provided in the substrate and before plating, or by embedding the conductive material over the entire surface of the substrate (through-hole There are two methods: forming a copper plating film, for example, over the inner wall (including the inner wall) by electroless plating and then embedding it. Of course, after embedding this conductive material, a plating film must be formed on the entire surface of the board, including the inner walls of the through-holes, by electroless plating. Lands of the plating film (on the surface, serve as connection electrodes for the chip) are formed at the sites of the through holes filled with the adhesive material. Therefore, this land is formed using the same wiring pattern forming process and the same copper plating film as the land formed in the area where no through hole is provided, so that the connectivity of the components is good. In other words, in surface mounting, parts are connected using plating film lands. Since the conductive material embedded in the through-hole has a structure sealed by the plated film land, there is no possibility that it will flow out during solder connection or sink into the through-hole and cause a connection failure. Furthermore, the formation of a plating film for land formation and the subsequent formation of a land pattern by selective etching involves plating both sides of the substrate, including the inner walls of the through holes, and forming a series of wiring patterns necessary for this plating film. Since this is done during the process, there is no need to set up a special process. [Example] An example of the present invention will be described below with reference to process diagrams shown in the drawings. Example 1 Figure 1 shows a method similar to the conventional manufacturing method of printed circuit boards.
After forming the first layer of copper plating film 10a in the through hole 3, a conductive material 9 is buried in the predetermined through hole 3,
7 is a sectional view of the main part of the substrate, showing a configuration in which a second layer of plated copper film 10b is then formed, and then wiring patterns 1a including lands 7 are formed on both surfaces of the substrate 1 by selective etching treatment. FIG. The process will be explained in more detail below with reference to the process diagram shown in FIG. FIG. 2 shows the manufacturing process of a printed circuit board using the well-known subtractive construction method. FIG. 2(a) shows the process of preparing a board in which an insulating base material 2 is coated with copper on both sides. Figure (b) shows the through-hole forming process in which through-holes 3 are drilled, and Figure (c) shows the process of applying electroless copper plating after applying a plating catalyst such as palladium to the entire surface of the board, including the inside of the through-hole. (d) shows a step of embedding a conductive material (silver paste, copper paste, etc.) 9 in a specific through hole 3 by printing, (e) ) is a step of forming a second layer of copper plating film 10b by applying a second electroless copper plating, and (f) of the same figure shows a step of forming a resist pattern 12 for forming a wiring pattern 1a including lands 7. Step of Forming: FIG. 3(g) shows the step of selectively etching the copper layer using the resist pattern 12 as a mask to form the wiring pattern 1a including the land 7. As described above, the basic printed circuit board manufacturing process is completed through the steps up to this point, but it is preferably continued to the next step. The figure (h) shows that after removing the resist pattern 12, the land 7 (including the through hole 3) necessary for connection is removed.
The process of manufacturing the printed circuit board according to this embodiment is now complete, showing the process of coating the surface of the board with a well-known solder resist 13. Next, following this manufacturing process, a mounting process in which electronic components are mounted on the obtained board 1 and connected by soldering will be described. Figure (i) shows a process in which an LSI chip is mounted as a single-sided mounting component 6, and its connection terminal 6a is connected to a land 7 formed on the through hole filled with a conductive material by solder reflow. (j) shows the process of further mounting the lead component 5, inserting the lead 5a into the through hole, and similarly connecting it with solder. The solder used for the surface mount component 6 had a higher melting point than that of the solder for the lead component 5, so that the connection of the surface mount component 6 would not be damaged when the lead component 5 was connected. In this way, it was possible to manufacture a printed circuit board suitable for high-density mounting in which the surface-mounted component 6 and the lead component 5 were mounted together. Embodiment 2 FIG. 3 shows an example in which a printed circuit board is manufactured by a well-known additive method instead of the subtractive method shown in FIG. 2. FIG. 5A shows a step of preparing an adhesive-coated substrate that has been treated as a base treatment so that a plating film to be formed in a later plating step will firmly adhere to the insulating base material 2. Figure (b) shows a through-hole forming process (same as Figure 2) in which a through-hole 3 is formed using a drill. FIG. 2(c) shows a process of forming the first layer of copper plating film 10a by applying electroless copper plating after applying a plating catalyst such as palladium to the entire surface of the substrate including the inside of the through holes (see FIG. 2). (same as Figure 2), Figure (d) shows the process of embedding a conductive material (silver paste, copper paste, etc.) 9 in a specific through hole 3 by printing (same as Figure 2), Figure (e) shows 2. This is the second plating process, in this case the process of forming a copper plating film 10b with a sufficient thickness required as a wiring conductor by electrolytic plating, from (f) to (j) in the same figure. The steps shown in FIG. 2 are the same as those shown in FIG. 2, so they will be omitted. In this way, a printed circuit board suitable for high-density packaging could be manufactured, as in the case of Example 1. Example 3 - Figure 4 shows a manufacturing method similar to that in Figure 3 of Example 2, but after applying a plating catalyst such as palladium to the entire surface of the substrate including the inside of the through-hole in Figure 3(c), The step of forming the first layer of copper plating film 10a by applying electroless copper plating (same as in FIG. 2) and the step of forming a conductive material (silver paste or copper paste, etc.) 9
2 is a cross-sectional view of a main part when the process of embedding by printing (same as in FIG. 2) is reversed and manufactured in the reverse order. In this case, although not shown in the drawings, after embedding the conductive material 9, a plating film 10a is formed over the entire surface of the substrate including the inside of the through hole. And this plating film 1
A wiring pattern 1a including a land 7 is formed on 0a. FIG. 5 shows that a surface mount component 6 and a lead component 5 are mixedly mounted on a board having the configuration shown in FIG. 4 in the same process as in FIGS. 2(i) and 2(j) of the first embodiment. , has been implemented. Similarly to any of the above examples, a printed circuit board suitable for high-density packaging could be manufactured. [Effects of the Invention] As described in detail above, according to the present invention, surface mount components and lead components can be mixed and mounted at high density. In other words, in the printed circuit board manufacturing method, even if many through-holes are provided for high-density mounting, the through-holes in the connection area necessary for surface mounting can easily be made into buried electrode connection lands with conductors. It became so. Additionally, in mounting, especially when mounting surface-mounted components, the land formed by filling the through-hole is made of a plating film, which allows for good solder connection of the components and achieves highly reliable mounting. Now I can do it.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a printed circuit board according to an embodiment of the present invention, FIG. 2 is a cross-sectional perspective view showing one process diagram, FIG. 3 is a cross-sectional perspective view similarly showing another process diagram, and FIG. FIG. 5 is a cross-sectional view of a printed circuit board similarly showing another embodiment, FIG. 5 is a mounting cross-sectional view showing another embodiment, and FIG. 6 is a cross-sectional view of a conventional printed circuit board with components mounted thereon. Explanation of symbols> 1... Board, 1a... Wiring pattern, 2... Insulating base material, 3... Through hole, 4... Solder, 5... Lead parts, 6... Surface mounting is a component (chip component), 7... Soldering is a land, 8... Paste solder, 9... Conductive material, 1o... Plated copper, 11... Connection hole, 12... -Resist pattern, 13...Solder resist.

Claims (7)

[Claims] 1. A step of preparing a substrate in which conductive foil is pasted on both sides of an insulating base material, a step of providing a through hole consisting of a through hole of a predetermined diameter in this substrate, a step of applying a plating catalyst in at least the through hole, A step of filling a conductive material into a predetermined specific through hole among the through holes, a step of applying electroless plating to the entire surface of the board including the inside of the remaining through hole, and a step of filling the through hole opening and the conductive material. a step of forming a resist pattern for forming lands in each of the filled through-hole traces and a wiring pattern connected to the lands; and a step of selectively etching the conductor foil using the resist pattern as a mask. A method for manufacturing a printed circuit board, comprising the step of removing the resist mask. 2. A step of preparing a substrate in which conductive foil is pasted on both sides of an insulating base material, a step of providing a through hole consisting of a through hole of a predetermined diameter in this substrate, a step of applying a plating catalyst in at least the through hole, A step of performing electroless plating on the entire surface of the substrate including the inside of the through hole to form a first plating film, a step of filling a predetermined specific through hole among the through holes with a conductive material, and a step of filling the remaining through hole with a conductive material. plating the entire surface of the substrate, including the inside of the through-hole, to form a second plating film, and forming a land at the opening of the through-hole and the trace of the through-hole filled with a conductive material, and connecting the land to the land. a step of forming a resist pattern for forming a wiring pattern; a step of selectively etching the conductive foil on which the plating film is laminated using the resist pattern as a mask to form a wiring pattern; and a step of forming a wiring pattern using the resist pattern as a mask. A method of manufacturing a printed circuit board, comprising the step of removing. 3. Instead of pasting conductive foil on both sides of the insulating base material, a substrate is coated with an adhesive to improve the adhesion between the base material and the plating film that will be formed in a later process on the surface of the insulating base material. 3. The method of manufacturing a printed circuit board according to claim 1, further comprising a step of preparing. 4. 4. The method of manufacturing a printed circuit board according to claim 2, wherein the plating treatment in the step of forming the second plating film is electrolytic plating or electroless plating. 5. 5. The method of manufacturing a printed circuit board according to claim 1, further comprising the step of forming a solder resist on the entire surface of the substrate except on the lands and in the through holes after the step of removing the resist mask. 6. Continuing to the method for manufacturing a printed circuit board according to claims 1 to 5, a lead of a lead component is inserted into the through hole.
A mounting method for electronic components in which lead components and surface-mounted components are mixed, which includes a process of mounting and arranging surface-mounted components on the lands of through-holes filled with conductive material and connecting them with solder. 7. 7. The electronic component mounting method according to claim 6, wherein the step of soldering the components is a step of soldering the surface-mounted components and the lead components in two stages using solders having different melting points.