JPS6175596A - Manufacture of through hole multilayer circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a multilayer circuit board in which a recess is formed on a board and a conductive circuit is formed in the recess, and a method for manufacturing the same, and particularly relates to a method for manufacturing the same. It can be applied to package substrates such as circuit boards, semiconductor element mounting substrates, chip carriers, and bin grid arrays that require high performance.

[Conventional technology]

Conventionally, a method for producing a multilayer circuit board with circuits in the recesses by forming recesses on a board involves cutting and removing a part of the board into a predetermined shape, and using a perforated ceramic sheet (green) before firing. There is a known method (1) in which a conductive circuit is formed by screen printing a conductive paste on a sheet (sheet), the sheets are then laminated, and a conductive paint is sucked or press-fitted into the hole to form a through hole. For plastic and metal substrates, a method is used in which circuits are formed and then the substrate is deformed by heating and pressure to form recesses (I
)It has been known. On the other hand, there is a method (buttons have been put into practical use) in which a part of a through-hole substrate on which a plurality of circuits are formed is removed, laminated and pressed, and then molten solder is flowed into the through-holes to connect the circuits of each layer.

[Problem that the invention seeks to solve]

By the way, high-density thin substrates that limit the density of circuits and the height of component mounting, substrates for mounting semiconductor elements, and semiconductor element packages that require a large number of connection conductors to be formed in a very limited area. It is effective for the substrate to have a cavity structure in which the substrate has a recess. However, with the conventional methods (1) to (1) above, it is extremely difficult to form conductors inside the cavity, connect those conductors to the outer layer circuit while maintaining high reliability, and also maintain high productivity. Met. For example, in the conventional method, method (1) uses a screen printing method, so as the thickness of the substrate increases or the circuit density increases, it is difficult to supply enough paste into the holes to connect each layer. was difficult. In addition, method (1) allows circuits to be formed inside recesses, but originally only one recess is formed in the inward wiring layer, and the surface circuit and the circuit inside the recess are separated to improve wiring density. I can't. and,
Method (1) is a method in which the electrical connection of each wiring layer is achieved by solder flowing into the through-holes, but it is extremely unreliable because blow holes and incomplete filling of solder are likely to occur when the solder flows. It is scarce.

The present invention provides a technology for forming a three-dimensional circuit with high reliability regardless of whether it is a ceramic or plastic substrate, and
The present invention provides an inexpensive multilayer circuit board that solves the above drawbacks.

[Means for Solving the Problems and Their Effects] The method for manufacturing a printed circuit board of the present invention will be specifically explained using a method using an adhesive sheet.

Figure 1 (a) shows two printed circuit boards (a) and (b).
is a partial cross-sectional view of the product before being bonded together using an adhesive sheet (c), and a through hole (4) forming a recess is shown in advance in the substrate (a) and the adhesive sheet e→. The base material (1) is not particularly limited and may be an inorganic material or an organic resin material. For example, ceramics such as alumina and silicon carbide, glass epoxy resin substrates,
There are glass polyimide resin substrates, paper epoxy resin substrates, glass triazine resin substrates, etc. A conductive film such as a copper foil or a vapor-deposited metal film may be previously formed on one or both sides of these base materials. (2) is a desired conductor formed by a photo-etching method using a photosensitive resin or a conventional method of screen printing a conductive paste. It is a 4f circuit.

Here, a hole may be drilled in advance in the substrate (A) using a drill or the like under NC control, and a (conduction fff circuit) 1≦ may be formed so that both surfaces of the substrate (A) are electrically connected.

(3) is a different metal layer formed on the conductor when (2) is the same metal as (5) forming the through hole. For example, when the metal (2) is copper, solder .

Examples include tin, nickel, and gold, but nickel, gold, and the like having a high melting point are preferably used. Here, the conduction circuit (2
) and the metal (5) are different types, the metal layer (3) is not particularly necessary. Two methods of forming a dissimilar metal layer on a conductor include plating into a desired shape before forming a conductive circuit pattern and then forming a conductive circuit by etching, and plating after forming a conductive circuit. There is a method of forming a dissimilar metal layer, but the method is not particularly limited.

Next, the substrates (a) and (b) are bonded together using an adhesive sheet (c). Although the method is not particularly limited, for example, press bonding using high temperature and high pressure may be used. Here, by stacking a substrate having a through hole forming a recess on the opposite side of the substrate (a), it is possible to achieve even higher density mounting.

In the printed circuit board, holes are formed at desired positions, and the entire board including the holes and the recesses formed after lamination is subjected to electroless plating or electroless plating and electrolytic plating to perform through-hole plating (5). Metals to be plated include nickel and copper. It is also possible to form a circuit on the plated metal layer (5) by photoetching the plated metal layer (5) on the surface of the substrate excluding the recessed portions after lamination, without forming a circuit in advance.

(4) is a penetrating portion formed at a desired position by punching with a die, drilling with a drill, and machining. (
5) is an adhesive sheet that was cut and removed in the same shape as (4).

FIGS. 1(b) and 1(c) are partial cross-sectional views of the multilayer printed circuit board after through holes are formed in the board. Said (1
) to (6) are the same as the previous time, and in (7), a photoresist film is formed on the desired through-hole portion, and the metal (
It is formed by etching only the metal layer (5), or by coating only the through-hole portion with through-hole plating and plating with a different metal, and selectively etching and sowing only the metal layer (5).

〔Example〕

A resist was formed on a double-sided copper-clad glass epoxy substrate using @photoresin, and then nickel plating was applied to a thickness of 5 μIn, and gold plating was further applied to a thickness of Q, 5 pm. Next, the resist was peeled off and alkali etching was performed to obtain a desired conductive circuit. At least one of each printed circuit board on which a conductive circuit was formed was cut and removed at a desired position using a mold.

Next, the adhesive sheet was cut and removed at a desired position (same as the one cut and removed above) using a mold. Therefore, the cut and removed adhesive sheet was combined with these printed circuit boards, and they were thermocompression bonded at high temperature and high pressure to form a laminated body.

Holes were then drilled using percentage control at positions where conduction was required between each layer. Furthermore, the entire surface of the substrate including the holes was subjected to usual pretreatment and electroless copper plating, and electrolytic copper plating was performed to a thickness of about 15 μm.

Therefore, the through-hole portions were tented with a photosensitive resin to form an etching resist.

Thereafter, only copper was selectively removed from this substrate by alkali etching to form through holes.

Therefore, a solder resist film was printed on areas other than the bonding terminals of the conductive circuit, and nickel and gold plating were applied on top of the printed solder resist film. Next, it was cut and removed using a mold to the required external dimensions.

Here, an example of a printed wiring board will be specifically described using FIG. 2(A). (1) is a terminal mounted on a printed wiring board by soldering, and the surface is soldered or gold plated. (This is to solve the problem that when a semiconductor sealing resin is poured into a cavity, the unevenness of the resin makes it impossible to mount it on a printed wiring board.

(■ is a terminal for wire bonding with a semiconductor, and is electrically connected to the mounting terminal (]) of the printed wiring board.The surface of the terminal is gold-plated. (4) is a cavity for mounting a semiconductor, and the surface layer is plated with gold.Furthermore, after the semiconductor is mounted in this cavity, a resin for semiconductor sealing may be poured into the cavity.

(5) is an adhesive sheet for bonding two printed wiring boards together.

Next, an example of a board for mounting electronic components is shown in Figure 2 (
This will be explained in detail using (b).

FIG. 2 (J) is a cross-sectional view of a three-layer pin grid array. (6) is a terminal for wire bonding to a semiconductor.

(7) l! , a Surpol for conducting electrical connection with the bottle, and its surface is gold-plated.

(8) is an inner layer pattern that is electrically connected to the through hole (7).

(9) is a terminal for semiconductor and wire bonding, and is electrically connected to the inner MJ pattern (8).

(10) is a cavity for mounting one body.

(b) is a die pad for mounting a semiconductor.

(12) is an adhesive sheet.

(13) is a conduction bottle when mounted on a printed wiring board.

〔Effect of the invention〕

As described above, according to the manufacturing method of the present invention, through-holes are formed by a general method, rather than by methods such as applying or inhaling conductive paint into the through-holes or flowing molten solder into the through-holes, and Since circuits can be formed even within the recesses formed in the substrate, it has become possible to manufacture highly reliable and inexpensive high-density mounting substrates using various insulating materials. Printed wiring boards made using this manufacturing method have electronic components mounted in the recesses of the board.
Tama 1 that can electrically connect electronic components and circuits inside the recess
When the present invention is used as a semiconductor package substrate such as a chip carrier pin grid array, wire bonding terminals can be arranged in several layers in an area (range) close to the semiconductor chip. This makes it possible to make the board much smaller than before and to make the length of the bonding wires uniform, allowing flexibility even when the number of input/output terminals increases.

[Brief explanation of the drawing]

FIG. 1(n) to FIG. 1(e) are cross-sectional views for explaining the flow sheet of the manufacturing method of the present invention. (1) Insulating substrate (2) Metal layer (copper) (3) Metal layer (copper) (4) Punched portion (5) Adhesive sheet (6) Through hole (η Metal layer (copper) (8) Through hole after pattern formation (a) and (b) are cross-sectional views of a printed wiring board (a) and a bin grid array (b), which are examples of the multilayer circuit board according to the present invention, (a) board mounting terminals (b) insulating substrate ( e) Wire bonding terminal (d) Semiconductor mounting cavity (e) Adhesive sheet (c Wire bonding terminal (first layer) (ω Through hole Φ) inner layer pattern (i) Wire bonding terminal (second layer) (j
) Cavity for semiconductor mounting (→ Die pad for semiconductor mounting (→ Adhesive sheet) Conductive bottle

Claims (7)

[Claims] (1) (a) A plurality of insulating substrates (a) and (b) each having a conductive circuit (2) formed of one or more metals on one or both sides, one part of which is a desired one. Consisting of one or more substrates (a) cut and removed in the shape (4) and a substrate (b) that is not cut and removed, an adhesive substance is interposed on one surface of the substrate (a) or (b). a step in which the substrates (a) and (b) are joined together, and a recess is formed by laminating and integrating these insulating substrates to form a multilayer circuit board;
(b) The multilayer circuit board has through holes formed at predetermined locations to form through holes (6) for electrically connecting the conductive circuit layers, and the metal (2) forming the surface of the conductive circuit (2). (c) Depositing a metal (5) different from 3) on the entire surface of the substrate including through holes (4) and recesses by a normal method; and (c) forming the outermost layer circuit (7) and through holes as necessary. Precipitated metal (5) formed on the entire surface except for the hole (6)
).) A method for manufacturing a through-hole multilayer circuit board having a circuit also in the recessed portion. (2) In the step (a), the cut and removed portions are combined so that they do not form through holes;
2. The manufacturing method according to claim 1, wherein recesses having circuits therein are formed on both sides of the substrate. (3) Among the plurality of substrates on which the conductive circuit (2) is formed, at least one substrate is pre-plated with through-hole plating. Manufacturing method in Section 2. (4) Metal (3) forming the surface of the conductive circuit (2)
4. The manufacturing method according to claim 1, wherein said metal is nickel, gold, or a composite thereof. (5) The manufacturing method according to any one of claims 1 to 4, wherein the insulating substrates (a) and (b) are made of organic resin. (6) After forming the through hole (6), all the conductive circuits are drawn out and connected on the board outline or outside, and the connecting conductor is further plated and then formed into a predetermined shape. A method of manufacturing a multilayer circuit board, which comprises cutting the connecting conductors into pieces and separating the connecting conductors. (7) The through-hole multilayer circuit board having a circuit also in the concave portion is any one of a printed wiring board, a chip carrier for mounting electronic components, and a pin grid array. The manufacturing method described in Section 6.