KR100632558B1 - Improved vacuum press apparatus and method - Google Patents

Abstract

The present invention relates to a laminating apparatus and method by vacuum press of a printed circuit board. More specifically, the present invention provides improved interlayer adhesion and reliability of a multilayer printed circuit board by applying a current to the heat plate by applying a projection welding method together with high thermal pressure in a vacuum press used for laminating a printed circuit board. It relates to a vacuum press apparatus and a method which can be performed.

Multilayer Printed Circuit Board, Press, Projection Welding, Crimping

Description

Improved vacuum press apparatus and method

1A to 1H illustrate a conventional method of manufacturing a multilayer printed circuit board according to a so-called B2IT method.

Figure 2 shows a pressing process according to a batch lamination method of a printed circuit board in the so-called B2IT method of the prior art.

3 shows a batch lamination process by a projection press process according to the present invention.

※ Explanation of main parts of drawing ※

31a, 31b: Copper foil layer with prepreg laminated 32a, 32b, 32c: 1 mm heat plate

33a, 33b: cushion 34a, 34b: release film

35a, 35b: Craft 36a, 36b: 8mm surface plate

37a, 37b: Additional copper foil layer 38, 39:-electrode

40: + electrode 41: top board

42: carrier plate 43a, 43b: hot plate

The present invention relates to a laminating apparatus and method by vacuum press of a printed circuit board.

More specifically, the present invention provides an improved interlayer adhesion and reliability of a multilayer printed circuit board by applying a high temperature pressure and a projection welding method in a vacuum press used when the printed circuit board is laminated, by applying a current to the heat plate. It relates to a vacuum press apparatus and a method which can be performed.

Manufacturing of printed circuit boards involves a number of substrate stacking processes. It is very important to apply uniform pressure and heat throughout the substrate in this lamination process, which is directly related to the reliability of the product.

1A to 1H illustrate a conventional method of manufacturing a multilayer printed circuit board according to a so-called B2IT method.

The silver bump 12 is formed by printing a silver paste several times on the copper foil layer 11 as shown in FIG. 1A.

As shown in FIG. 1B, a prepreg 13 is laminated on the copper foil layer 11 to cover the silver bumps 12.

In FIG. 1C, another copper foil layer 14 is vacuum pressed on the surface on which the prepreg 13 of the copper foil layer 11 is laminated, and the copper foil layer 11 and the copper foil layer 14 are made of silver bumps 12. ) Are connected to each other.

In Fig. 1D, an etching resist pattern is formed by applying a dry film 15 to both surfaces of the substrate, exposing and developing.

In Fig. 1E, the substrate is immersed in etching to form circuit patterns on the copper foil layers 11 and 14 according to the etching resist pattern.

In FIG. 1F, another copper foil layers 16 and 17, on which silver bumps are formed and prepregs are laminated in the same manner as shown in FIG. 1B, are preliminarily laminated on both sides of the substrate, and vacuum press is applied to the copper foil layer (by silver bumps). 16 and 17 are connected to the inner circuit pattern.

Then, in Fig. 1G, a dry film is applied to the copper foil layers 16 and 17, and the etching resist pattern 18 is formed by exposure and development.

In Fig. 1H, the substrate is etched to form circuit patterns on the copper foil layers 16 and 17, and the dry film is peeled off.

Figure 2 shows a pressing process according to a batch lamination method of a printed circuit board in the so-called B2IT method of the prior art.

As shown in Fig. 2, copper bumps 21a and 21b and additional copper foil layers 27a and 27b on which silver bumps are formed and prepregs are stacked, 1 mm thick surface plates 22a, 22b and 22c, and cushions (23a, 23b), release films 24a, 24b, 8m thick heat plates 26a, 26b, craft portions 25a, 25b, top boards 28, and carrier plates 29 are disposed. Hot plates 30a and 30b are disposed on the outside of the substrate to apply pressure and heat. Then, when heat is applied to the entire substrate while applying pressure up and down as indicated by the arrow, the layers between the heat plate and the heat plate are combined to complete a multi-layer printed circuit board.

At this time, the plates 22a, 22b, 22c; 26a, 26b serve to disperse the pressure and separate the product from the product so that pressure can be uniformly transmitted throughout the substrate.

As described above, in the manufacturing process of the multilayer printed circuit board, a plurality of substrate pressing processes as shown in FIGS. 1A and 1F or 2 are inevitably included. The pressurization process is usually performed by a vacuum press apparatus, and in the pressurization process, it is the most important task to apply pressure evenly over the entire substrate and not to drop the adhesive force between the layers after pressing.

If the pressure is not evenly transmitted throughout the board, the reliability of the product is reduced and it is a major cause of many errors in subsequent processes, which is very fatal in the manufacture of a printed circuit board. In addition, if the adhesion between the layers, in particular the adhesion of the bumps is poor, there is a fatal defect that the layers are separated when using the final product, the reliability of the printed circuit board manufacturing is extremely degraded.

However, in the conventional simple process of applying pressure and heat as shown in FIGS. 1A to 1H and 2, the bumps are simply adhered by pressure, so that there is a high possibility of interlayer bump separation in the finished product. In addition, the part where the inter-layer bump adhesion failure occurs frequently, particularly a reliable adhesive force is required as a part through the electrical signal, there is a problem in increasing the reliability of the product by applying the same treatment to other parts.

An object of the present invention is to provide a press apparatus and a press method that can improve the adhesion reliability between the layers of the printed circuit board in the heating press process accompanying the manufacturing process of the printed circuit board.

A printed circuit board press apparatus according to an embodiment of the present invention, the crimping unit for crimping the laminated substrate; A bath portion disposed between the substrates to apply uniform pressure to the entire substrate; And a power supply unit connected to each of the source units to apply a current.

The printed circuit board pressing method according to an embodiment of the present invention comprises the steps of: preliminarily stacking a plurality of insulating layers and circuit layers; Disposing a sustain plate between the insulating layer and the circuit layers; Connecting an electrode to the surface plate; Pressing the substrates; And flowing a current through the electrode to the surface plate.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3 shows a projection press process according to the present invention in a batch lamination method of a printed circuit board.

As described above, there are various batch lamination methods in addition to the sequential build-up method in the manufacture of the multilayer printed circuit board, but all of these processes are pressurized. In the present embodiment, the silver bumps are formed through the B2IT method, that is, the copper foil layer through several printing processes, and the copper bumps on which the silver bumps are formed are pressed onto the insulating layer, so that the silver bumps pass through the insulating layer to electrically connect the copper foil layers to each other. The connection method will be described as an example.

As shown in Fig. 3, a circuit layer composed of copper foil layers 31a and 31b on which silver bumps are formed and prepregs are laminated, and additional copper foil layers 37a and 37b, and heat plates 32a and 32b having a thickness of 1 mm. 32c, cushions 33a and 33b, release films 34a and 34b and 8m thick heat plates 36a and 36b, craft portions 35a and 35b, top board 41 and carrier plate 42 do. On the outside of the substrate are hot plates 43a and 43b that apply pressure and heat.

Silver bumps are formed on the copper foil layers 31a and 31b, and an insulating layer is laminated so that the silver bumps penetrate the insulating layer by a pressing process as shown in Fig. 1C.

In this embodiment, the insulating layer is already laminated to the copper foil layers 31a and 31b through a separate pressing process. However, only the silver bumps are formed in a separate process and the silver bumps are pressed together with the other layers. It is also possible to pass through.

Through the pressurization process, the silver bumps conduct the copper foil layers 31a and 31b and the additional copper foil layers 37a and 37b to each other while being in contact with the additional copper foil layers 37a and 37b.

The 1 mm thick plates 32a, 32b and 32c and the 8 m thick plates 36a and 36b are each made of conductive stainless plates, and the pressure applied by the hot plates 43a and 43b can be evenly transmitted. It distributes evenly across the substrate and serves to separate the product and the product. In addition, the craft parts (35a, 35b) also serves to allow the pressure applied to be evenly transmitted and the heat to be slowly transferred from the hot plate.

1 mm thick plates 32a, 32b and 32c are disposed between the inner layer circuits, and 8m thick plates 36a and 36b are disposed outside the substrate.

The cushions 33a and 33b correct the pressure difference between the circuit portion and the resin portion of the inner layer substrate after etching. In addition, the release films 34a and 34b allow the cushions 33a and 33b to be easily separated from the heat plate after the pressing process.

On the other hand, in order to perform projection welding for strengthening the adhesion of the bumps at the same time to pressurization, the electrodes are connected to the 1 mm thick surface plates 32a, 32b, and 32c as shown in FIG.

Meanwhile, the projection welding method is a method of welding by energizing a plurality of different contacts at one time, and refers to a multi-contact welding method using a spot melting method.

When the heat plates 32a, 32b, and 32c are in a high temperature state, if electricity is applied to the contact portions of the electrodes, the resistance increases, which increases the probability that the projection welding will fail. It is preferable to apply pressure to the hot plates 43a and 43b, and then perform projection welding and raise the temperature thereafter.

The best bump adhesion reliability can be realized by incorporating a projection welding method into a so-called B2IT method in which a conventional bump penetrates the insulating layer and simultaneously attaches the layers to electrical connections, or a method of bonding the layers using an adhesive.

As shown in FIG. 3, the electrodes are connected to the heat plates 32b so that a positive voltage is applied, and the electrodes are connected to the heat plates 32a and 32c so that a voltage is applied to the heat plates 32a, 32b and 32c. ) Is part of the closed loop.

Then, pressure is applied using the hot plates 43a and 43b, and at the same time, current is passed through the electrodes 38a, 32b, and 32c through the electrodes 38, 39, and 40 so that the bumps are subjected to projection welding. Then, heat is generated on the hot plates 43a and 43b under pressure to bond the copper foil and the prepreg portion.

In the case where the number of layers to be laminated is small, it is preferable to carry out current welding to the electrodes 38, 39 and 40 at once to perform projection welding collectively. When the number of layers to be laminated is large, the heat plates 32a, 32b, Since the current flowing to 32c) becomes large, excess current flows by flowing current through the electrodes 39 and 40, or vice versa after the current flows through the electrodes 38 and 40, or the contact portion is damaged. It is desirable to prevent such a phenomenon from becoming.

In addition to the electrode connection method as shown in FIG. 3, the electrode connection method applied to the surface plates may be modified as much as the number and thickness of the layers to be pressed.

According to the printed circuit board press apparatus and method using the projection welding method of the present invention, it is possible to improve the adhesion reliability of the interlayer bumps of the printed circuit board in the pressing process.

The printed circuit board press apparatus and method of the present invention show superior interlayer bonding reliability than adhesion by bumps or adhesives in the conventional high temperature crimping method.

According to the experiment, in the general high temperature crimping method, the interlayer bump adhesion strength was about 0.6-0.8 kgf / cm2, but the interlayer bump adhesion strength was about 2kgf / cm2 or more by the printed circuit board press apparatus and method of the present invention. appear.

Although the present invention has been described above by way of examples, the scope of the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the present invention. It is intended that the scope of the invention only be limited by the following claims.

Claims (4)

A crimp unit for crimping a plurality of substrates including circuit layers stacked through bumps; A bath portion disposed between the plurality of substrates to apply uniform pressure to the entire substrate; And A power supply unit connected to each of the source units to apply a current; And a bump welded onto the bump by the applied current. The method of claim 1, Printed circuit board press apparatus, characterized in that the anode and the cathode of the power supply unit is connected to each other a different portion. Preliminarily stacking a plurality of substrates composed of circuit layers stacked through bumps; Disposing a sustain plate between the plurality of substrates; Connecting an electrode to the surface plate; Pressing the substrates; And Flowing a current through the electrode to the surface plate; And a bump welded by the current. The method of claim 3, Connecting the electrode to the surface plate, Printed circuit board press method comprising the step of connecting a different electrode to each of the substrate.

Images