JPS6155995A - Method of producing 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 [Industrial Field of Application] The present invention relates to a method for manufacturing a multilayer wiring board in which inclusion of voids is suppressed.

In order to process large amounts of information at high speed, information processing equipment uses IC,
High-density packaging is being carried out by making extensive use of semiconductor elements such as LSI.

In other words, multilayer boards are used for printed wiring boards on which components are mounted, but the number of constituent layers is gradually increasing.
Recently, devices exceeding 1ON have been put into practical use.

Here, IC: an active element such as , l, 81 or a capacitor.

In order to mount passive elements such as resistors, the multilayer printed wiring board is provided with through holes at necessary locations at a standard pitch of 2.5m++.

In addition, these parts are miniaturized, and their shapes and lead wire spacing are standardized to integral multiples of the standard dimensions of 2.5 cranes.

As described above, due to the miniaturization of mounted components and the increase in capacity and standardization of semiconductor elements, the wiring patterns of multilayer printed wiring boards (hereinafter referred to as "boards") have also become finer, and the pattern width has become 150 mm.
Threads on the order of micrometers have also been put into practical use and are used for high-density wiring.

In this way, the substrates used in information processing devices are multi-layered and have fine patterns formed on them, so the insulation between the wiring patterns must be maintained completely and without voids between the layers. It is necessary for

Therefore, it is desired to establish a method for manufacturing a multilayer substrate that contains fewer voids and has uniform in-plane characteristics.

[Conventional technology]

Multilayer boards are manufactured by laminating multiple double-sided printed boards with pre-prepared patterns in a lamination mold with prepreg sandwiched between them, and using reference pins to accurately align them and heat-press them to fuse and fuse them together. do.

Here, the pattern is formed using copper-clad lamination and photo-etching technology (
Prepreg is a bonding sheet made by impregnating glass cloth with semi-cured epoxy resin.

Fig. 3 shows a conventional manufacturing method, in which printed A boards 2 with conductor pattern layers l formed on both sides are sandwiched between prepregs 3 and alternately stacked on a lamination mold 4, and are positioned correctly using reference pins 5. do.

Next, the copper-clad laminates 6 are used as upper and lower layers, and the laminate mold 4 in which the printed circuit boards 2 are stacked in this way is heated and pressed with a hot plate 8 equipped with a heater through a cushioning material 7 to integrate the multilayer boards. ing.

Now, when the stacking mold 4 is used to position and stack the layers, there is a large amount of air inside.If the prepreg is simply melted by heating and pressurizing it in this state, the pressure will be uniform and the contained air and other gases will be added. Since it is held in an uncut state, voids occur.

Therefore, in the past, a copper foil or the like was pasted on one side of the cushion material 7 to make the center part convex, so that the pressure on the cushion material 7 was applied from the center part to the peripheral part.

In this way, the melting of the prepreg 3 starts from the center, so the gas gradually moves from the center to the periphery, and the resin constituting the prepreg 3 also flows evenly to the periphery, so that the film thickness distribution becomes uniform.

Conventionally, by processing the cushion material 7 in this way, voids were reduced and the welding characteristics were equalized, but processing of the cushion material was troublesome, and the board was affected by the distribution of voids and the thickness distribution of the multilayer board. The problem is that the characteristics are not uniform.

[Problem that the invention seeks to solve]

As described above, multi-N substrates are formed by heating and pressurizing a laminated mold in which wiring boards are laminated to fuse the prepreg to the substrate, but in this case, voids are not removed sufficiently, and the laminated mold is heated and pressed. The problem is that the reproducibility of the characteristics of the substrate is not sufficient.

[Means for solving problems]

The above problem occurs when multiple printed wiring boards with pattern formation are stacked on a stacking mold via prepreg, aligned, and then heated and compressed using a hot plate to integrate them. This problem can be solved by a method for manufacturing a multilayer wiring board that performs pressure molding using a hot plate having a shaped pressure surface.

[Effect]

The present invention processes the cushion material, thereby making the pudding 1
−． Instead of the conventional method of applying pressure preferentially to the center of one board, the hot plate itself is formed so that the center is convex, thereby manufacturing a multilayer board with few voids and excellent properties. It is.

〔Example〕

FIG. 1 is a block diagram of a lamination press embodying the present invention, and the arrangement of printed circuit boards 2 and prepregs 3, which are positioned and laminated using a lamination mold 4, is the same as in the conventional press.

That is, using the reference pin provided in the laminated mold 4,
The printed i-boards 2 and prepregs 3 are arranged alternately, and copper-clad laminates 6 are arranged above and below for accurate positioning.

On the other hand, the cushion material 9 is not subjected to any processing.

Further, the hot plate 10 is provided with steps in the shape of concentric circles or concentric squares, and the center portion is formed in a convex shape.

If the hot plate 10 with steps is used in this way, the effect is the same as when using a cushion material with convex steps, but the reproducibility is excellent because the center position is fixed and permanent. good.

However, in the case of processing into a resin/notion material, it is necessary to adjust the level difference depending on the area of the substrate to be heated and pressurized.

FIG. 2 shows this relationship, with the horizontal axis representing the substrate area and the quilt axis representing the height difference. As can be seen from the figure, the height of the convex portion is only about 200 μm at most.

As described above, in the present invention, it is only necessary to prepare the hot plate 10 according to the area of the substrate to be used, and thereby it is possible to manufacture a multilayer substrate with fewer voids and excellent reproducibility of characteristics. can.

〔Effect of the invention〕

As described above, by carrying out the present invention, it becomes possible to eliminate the complexity of processing into a cushion material and to manufacture a multilayer substrate with excellent reproducibility.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a lamination press embodying the present invention. Figure 2 is a diagram showing the relationship between the board area and the hot plate step. FIG. 3 is a sectional view showing the configuration of a conventional lamination press. In the figure, 2 is a printed circuit board, 3 is a prepreg, 4 is a laminated mold, 5 is a reference bottle, 7.9 is a cushioning material, and 8.10 is a hot plate.

Claims (1)

[Claims] Multiple patterned printed wiring boards are stacked in a stacking mold via prepreg, aligned, and then heated and compressed using a hot plate to integrate them. A method for manufacturing a multilayer wiring board, characterized by performing pressure molding using a hot plate.