JP2009059814A - Manufacturing method of multilayer printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a low-cost multilayer printed board of high quality in which a power supply defect due to insufficient charging of conductive paste and a short-circuit defect due to a spill of conductive paste can be eliminated. <P>SOLUTION: The manufacturing method of the multilayer printed board as a first embodiment of the present invention includes an etching stage of etching a thin metal layer 2 formed on a surface of a resin film 1 to form circuit patterns 3; a via-hole forming state of boring the resin film 1 from the surface on the opposite side from the circuit pattern 3 to form a plurality of via holes 4 reaching the circuit pattern 3; a sintered body arranging stage of arranging sintered bodies 5 one by one in the respective via-holes 4; a sintered body fixing stage of bringing the respective sintered bodies 5 arranged in the sintered body arranging stage into contact with the circuit patterns 3 forming bottom portions of the via-holes 4 and fixing them; and a substrate connecting stage of stacking a fourth circuit pattern film 40 formed in the sintered body fixing stage to form electric interlayer connections of the circuit patterns 3 disposed in multiple layers through the sintered bodies 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer printed circuit board in which a plurality of circuit pattern layers are connected with each other by a conductive material provided in a via hole formed in an insulating base material.

  As a conventional multilayer printed circuit board manufacturing method, a conductive paste in which a resin component as a binder is added to metal particles and an organic solvent is filled in a via hole formed in a resin film, and the conductive paste is filled in the via hole. Thus, a manufacturing method for performing interlayer connection of a plurality of circuit pattern layers is known (see, for example, Patent Document 1).

In such a manufacturing method, when filling the conductive paste into the via hole, the protective film is not applied to the surface of the resin film other than the via hole so as to adhere the conductive paste to the surface of the resin film other than the via hole. Is attached, the conductive paste is filled in the via hole, the organic solvent is dried, and then the protective film is peeled off from the resin film.
JP 2001-24323 A

  However, in the above prior art, when the protective film is peeled off, the conductive paste is collapsed or the conductive paste is dropped onto the resin film, resulting in problems such as deterioration of energization performance and short circuit failure. For example, this problem becomes significant when a conductive paste having a very high metal content is employed in order to improve the reliability such as the conductivity of the interlayer connection portion.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a multilayer printed circuit board which can eliminate a current-carrying failure due to insufficient filling of the conductive paste and a short-circuit failure due to spilling of the conductive paste.

  The present invention employs the following technical means to achieve the above object. A first invention relating to a method for manufacturing a multilayer printed circuit board includes a circuit pattern forming step of forming a circuit pattern (3) on the surface of an insulating base (1), and a circuit pattern (3 on the insulating base (1). ) And a via hole forming step of forming a plurality of via holes (4) reaching the circuit pattern (3) by drilling from the surface opposite to the surface, and consolidating the aggregate of conductive particles in each via hole (4) by sintering The sintered body arranging step of arranging the sintered bodies (5) formed one by one, and the sintering for fixing each of the sintered bodies (5) arranged in the sintered body arranging step in the via hole (4) The printed circuit board (40) obtained in the bonded body fixing step and the sintered body fixing step is laminated to electrically connect the circuit patterns (3) arranged in multiple layers via the sintered body (5). And a substrate connecting step.

  According to the present invention, since the electrical interlayer connection of the printed circuit board can be performed without filling the conductive paste into the via hole, the protective film necessary for filling the conductive paste is not necessary, and the manufacturing process can be simplified. At the same time, it is possible to prevent the conductive paste from coming off or spilling, which may occur when the conventional protective film is peeled off. Accordingly, it is possible to provide a method for manufacturing a multilayer printed board with high reliability in connection with the printed board, which eliminates the failure of energization due to insufficient filling of the conductive paste and the short-circuit failure caused by spilling of the conductive paste. In addition, since the protective film can be eliminated, the manufacturing process can be simplified, and a method for manufacturing a multilayer printed circuit board having low cost and high quality can be provided.

  Moreover, 2nd invention is a circuit pattern formation process which forms a circuit pattern (3A) in the surface of an insulating base material (1), and the surface on the opposite side to a circuit pattern (3A) in an insulating base material (1). A via hole forming step for forming a plurality of via holes (4) reaching the circuit pattern (3A) by drilling from the inside, and by consolidating the aggregate of conductive particles by sintering, the via hole (4) does not protrude to the outside The sintered body (5A) formed in the size is placed in each via hole (4) one by one, and the circuit pattern film (30A) created in the sintered body placement process is laminated and heated. The circuit pattern (3A) and the sintered body (5A) in the adjacent circuit pattern film (30A) are brought into contact with each other in the via hole (4) by pressing while the circuit pattern is arranged in multiple layers. 3A) and the substrate connection step of electrically interconnecting the, characterized in that it comprises a.

  According to this invention, the sintered body having the function and effect of the first invention and having a size that does not protrude to the outside from the via hole is disposed in each via hole. Since the step of fixing inside and the step of electrically connecting the multilayer printed circuit boards can be performed at the same time, the manufacturing process is further simplified, and a method for manufacturing a multilayer printed circuit board with higher productivity is provided. be able to.

  The conductive particles preferably contain silver particles and tin particles, and the content ratio of the tin particles to the conductive particles is preferably in the range of 20 to 80% by weight. According to this invention, the inclusion of silver particles and tin particles can provide conductive particles that are relatively low in oxidizability and that can be easily sintered.

  Furthermore, by setting the content ratio of the tin particles to the conductive particles in the range of 20 to 80% by weight, the alloy layer at the bonded interface of the sintered body can be ensured in an appropriate state, and the balance between the conductivity and the bondability is reliable. A highly sintered body can be provided.

  In addition, the sintered body (5, 5A) is obtained by forming a paste (70) produced by mixing conductive particles containing silver powder and tin powder with a solvent into a predetermined shape using a metal mask (80). Then, it is preferably manufactured by performing a sintering treatment by heating at a high temperature and further performing a washing treatment for carbide.

  According to the present invention, a sintered body having an appropriate shape and size can be obtained from the viewpoint of electrical conductivity and bonding with a circuit pattern by producing a sintered body by molding a paste using a metal mask. Can be mass-produced.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means shows an example of a correspondence with the specific means of embodiment description later mentioned.

(First embodiment)
1st Embodiment which is an example of the manufacturing method of a multilayer printed circuit board is described using FIGS. 1-4. FIGS. 1A to 1E are cross-sectional views showing the outline of the manufacturing process of the multilayer printed board in the first embodiment.

  First, as shown to Fig.1 (a), the film formed by affixing the metal layer 2 which is a conductor on the one side surface of the resin film 1 which is an insulating base material is prepared. The resin film 1 is, for example, a thermoplastic resin film having a thickness of 25 to 75 μm composed of 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin. The metal layer 2 is formed of, for example, a copper foil having a thickness of 18 μm.

  Next, the circuit pattern formation process which forms the circuit pattern comprised with a conductor on the surface of the resin film 1 is implemented. The circuit pattern forming step can be performed by etching, printing, vapor deposition, plating, etc. In this embodiment, as shown in FIG. 1B, the film of FIG. This is performed by an etching process in which a pattern is formed by etching to form the first circuit pattern film 10 on one side.

  Next, as shown in FIG.1 (c), the bottomed via-hole 4 which makes the circuit pattern 2 the bottom face to the resin film 1 by irradiating a carbon dioxide laser from the resin film 1 side in which the metal layer 2 is not provided. Are formed to form a second circuit pattern film 20 (via hole forming step). The opening diameter of each via hole 4 is such a size that one sintered body 5 arranged in the sintered body arranging step described later can be accommodated in the via hole. In other words, the opening size of the via hole 4 is larger than the portion having the maximum diameter of the sintered body 5 formed in a spherical shape, a cylindrical shape, a rectangular parallelepiped shape or a cubic shape.

  The part of the circuit pattern 3 that becomes the bottom surface of the via hole 4 is a part that becomes an electrode when the multilayer circuit pattern 3 is connected between the layers in the substrate connection process described later. In forming the via hole 4, the circuit pattern 3 is prevented from being perforated by appropriately adjusting the output of the carbon dioxide gas laser and the irradiation time.

  In addition to the carbon dioxide laser, an excimer laser or the like can be used for forming the via hole 4. A via hole forming method by drilling other than laser or the like is also possible, but drilling with a laser beam can make a hole with a fine diameter so that the circuit pattern 3 is not excessively damaged.

  Next, as shown in FIG. 1 (d), one sintered body 5 previously generated from an aggregate of conductive particles by a sintering process is disposed in each via hole 4, and the third circuit pattern film 30 is formed. Create (sintered body arrangement step). The sintered body 5 in the state of being arranged in this step preferably has the same height as the surface of the opening edge of the via hole 4 or slightly protrudes, and the inner surface of the via hole 4 and the sintered body in the via hole 4 A gap is preferably formed between the outer surface 5 and the outer surface 5. This is because the deformation amount of the sintered body 5 can be released so as to fill the gap when the sintered body 5 is deformed in the subsequent sintered body fixing step.

  The sintered body 5 is formed by previously forming an aggregate of powders of several kinds of conductive substances into a predetermined shape and a predetermined size under pressure, and heating at a temperature below the melting point between the powder particles. It is created by solidifying (consolidating) by generating a binding force. Each sintered body 5 arranged in the via hole 4 serves as an interlayer connection member 6 for electrically connecting the layers of the multilayer printed board in a substrate connection process described later.

  In the present embodiment, the conductive particles are composed of silver (Ag) particles and tin (Sn) particles. And the content rate of the tin particle with respect to the whole electroconductive particle is the range of 20-80 weight%, More preferably, it is the range of 30-50 weight%. This is because when the content of the tin particles is less than 20% by weight or more than 80% by weight, the alloy layer at the joining interface of the sintered body becomes thin, so that the balance between the electrical conductivity and the joining property is preferable. This is because high reliability cannot be obtained. And when the content rate of the said tin particle is the range of 30 to 50 weight%, as a sintered compact of a tin particle and a silver particle, the balance of electroconductivity and bondability will be more excellent.

When the sintered body 5 is formed into a spherical shape, the mixture of the tin particles and silver particles is melted at a high temperature, sprayed on the rotating disk to a predetermined particle diameter, and centrifuged. It is formed by being dispersed by force. When the cooling thus shaped spheres to a to a predetermined temperature, it is possible to produce spherical sintered bodies composed of the Ag 3 _Sn and Ag · Sn solid solution (ball-shaped sintered body).

  One size of the sintered body 5 of the present embodiment is such that the length of the portion with the largest dimension (the length of the diameter when the sintered body is spherical) is the resin film 1 (insulating base material 1). ) In the range of t to 1.4 t with respect to the thickness t, and more preferably in the range of t to 1.3 t. This is because by using the sintered body 5 having such a size, it is possible to obtain appropriate electrical conductivity and bondability as a sintered product of tin particles and silver particles. For example, with respect to a resin film 1 having a thickness of 75 μm and a copper foil (circuit pattern) having a thickness of 18 μm, the spherical sintered body 5 is aimed to have a diameter of 90 μm. Use one that meets the range.

  FIGS. 2A and 2B are schematic views showing the procedure of the sintered body arranging step in the manufacturing process of the multilayer printed board. This sintered body arranging step is performed by a sintered body setting device using a metal mask 63 as shown in FIG.

  This sintered body setting apparatus is baked by a metal mask 63 having a plurality of through holes 64 having a predetermined position and a predetermined shape, and a rotary moving body 60 having a rotating portion 6 and a curtain portion 62 depending from the rotating portion 6. One ligated body 5 is led to each via hole 4 one by one. The plurality of through holes 64 are formed in such a size that the sintered body 5 can be dropped, and are provided in the metal mask 63 so as to correspond to all the via holes 4 formed in the second circuit pattern film 20. ing.

  First, the second circuit pattern film 20 is placed on the metal mask 63 so that all the via holes 4 correspond to the through holes 64. Then, a larger number of sintered bodies 5 than the number of via holes 4 are placed on the surface of the metal mask 63, and the sintered body setting device is operated so as to move toward the through hole 64 while rotating the rotating portion 6. Then, as the rotating part 6 moves, the sintered body 5 is sequentially guided to the through hole 64 by the curtain part 62 that rotates. The sintered bodies 5 guided to the through holes 64 fall one by one from the through holes 64 and are accommodated in the via holes 4, and a third circuit pattern film in which one sintered body 5 is arranged in each via hole 4. 30 is completed (see FIGS. 2A and 2B).

  Further, the sintered body 5 is arranged by arranging the sintered body 5 in the via hole 4 on the circuit pattern film 20 without using a metal mask, and collecting the excess sintered body 5 remaining on the film with a squeegee. You can also.

  Next, as shown in FIG. 1 (e), the sintered body 5 is deformed in the via hole 4 to form an interlayer connection member 6 and fixed in the via hole 4 to form a fourth circuit pattern film 40. (Sintered body fixing step).

  As a method of fixing the sintered body 5 in the sintered body fixing step, a method of deforming and fixing the sintered body 5 by pressurizing the sintered body 5, and between the sintered body 5 and the inner surface of the via hole 4 are used. A method of fixing by applying surface tension by applying a solvent to the surface, a method of fixing by causing diffusion of tin particles from the surface of silver particles by applying ultrasonic vibration, and silver particles by heating to a predetermined temperature There is a method in which tin particles are melted and fixed from the surface. The term “fixing” as used herein includes not only a strong fixing force that does not move even when an external force is applied, but also a fixing force that allows a subsequent substrate connection process to be performed successfully.

  Further, the interlayer connection member 6 is sintered, for example, by performing a roll press process that applies a compressive load to the surface of the third circuit pattern film 30 while gradually rotating the roll member 50 from one side to the other side. It can also be formed by deforming the body 5 so as to follow the inner shape of the via hole 4 (see FIG. 3).

  Next, a substrate connecting process for electrically connecting the circuit patterns 3 of a plurality of circuit pattern films arranged in multiple layers will be described. In this substrate connection step, first, a plurality of fourth circuit pattern films 40 (two in this embodiment) and the first circuit pattern film 10 positioned on the uppermost surface are laminated. Then, both the two lower fourth circuit pattern films 40 and the upper first circuit pattern film 10 are laminated with the surface on which the circuit pattern 3 is provided facing down, and are adjacent to each other. With the circuit pattern 3 of each circuit pattern film and the interlayer connection member 6 facing each other, the upper and lower surfaces of these multilayer printed boards are pressed while being heated by a vacuum heating press. For example, pressurization is performed for 10 to 20 minutes at a pressure of 1 to 10 MPa under an atmospheric temperature of 250 to 350 ° C.

  By this substrate connection step, the plurality of fourth circuit pattern films 40 and the first circuit pattern film 10 are heat-fused and integrated with each other, and are adjacent to each other through the interlayer connection member 6 in the via hole 4. A multilayer printed circuit board 100 in which the circuit patterns 3 of the circuit pattern film are electrically connected to each other is obtained (see FIG. 4). FIG. 4 is a schematic cross-sectional view showing a state in which a plurality of circuit pattern films arranged in multiple layers are electrically connected to each other in the manufacturing process of the multilayer printed board according to the present embodiment.

  In this state, the interlayer connection member 6 in the via hole 4 is pressed with a constant force, so that it is pressed against the surface of the circuit pattern 3 constituting the bottom of the via hole 4. Due to this pressure contact state, the Sn component in the interlayer connection member 6 and the Cu component of the copper foil constituting the circuit pattern 3 are mutually solid-phase diffused, and a solid-phase diffusion layer is formed at the interface between the interlayer connection member 6 and the circuit pattern 3. Therefore, circuit patterns arranged in multiple layers can be electrically connected.

  As described above, the manufacturing method of the multilayer printed circuit board 100 according to the present embodiment includes an etching process for forming the circuit pattern 3 by etching the thin metal layer 2 formed on the surface of the resin film 1, and the resin film 1. A via hole forming step of forming a plurality of via holes 4 reaching the circuit pattern 3 by drilling from the surface opposite to the circuit pattern 3, and a sintered body formed by consolidating each via hole 4 by sintering conductive particles Sintered body fixing step for fixing each of the sintered bodies 5 arranged in the sintered body arranging step to be in close contact with the circuit pattern 3 forming the bottom of the via hole 4 The fourth circuit pattern film 40 created in the process and the sintered body fixing process is laminated, and the circuit patterns 3 arranged in multiple layers via the sintered body 5 are electrically connected to each other. Includes a board connecting step of continued, the.

  According to this manufacturing method, by disposing one sintered body 5 having a predetermined size in the via hole 4, the conductive material can be fixed in the via hole 4 in a stable posture. It is possible to eliminate the loss and collapse of the conductive material in the via hole 4 and the spillage from the via hole 4 that hinder the conductivity. Therefore, since it is possible to connect the electrical layers of the printed circuit board without using the conductive paste, a protective film necessary for filling the conductive paste is not necessary, and the manufacturing process can be simplified and has been a problem in the past. In addition, it is possible to prevent the conductive paste from dropping or spilling, which may occur when the protective film is peeled off.

(Second Embodiment)
2nd Embodiment demonstrates the other example of the manufacturing process of a multilayer printed circuit board. The manufacturing process of the multilayer printed circuit board 100A described in the present embodiment has no sintered body fixing process as compared to the manufacturing process described in the first embodiment, and includes a via hole forming process, a sintered body arranging process, and a board connecting process. The contents are different. Other steps are the same as those described in the first embodiment, and a description thereof will be omitted.

  In the via hole forming step in the manufacturing process of the multilayer printed circuit board 100A, the circuit pattern 3A of the circuit pattern film that is adjacent to the diameter of the opening of the via hole 4 in the interlayer connection in the subsequent substrate connecting step may enter the via hole 4. It is formed in a size that can be made.

  Next, in the sintered body arrangement step, a sintered body 5A is used in which conductive particles having the same components as those in the first embodiment are formed into a size that does not protrude from the inside of the via hole 4 by a sintering process. In this step, the sintered body 5A thus formed is arranged one by one in each via hole 4 to form the third circuit pattern film 30A.

  That is, the height of the top surface of the sintered body 5 </ b> A disposed in the via hole 4 is positioned below the surface of the opening edge of the via hole 4 by a predetermined distance. The predetermined distance is set to be equal to or smaller than the thickness of the circuit pattern 3A to be contacted in the subsequent substrate connection process. The sintered body 5A is different in size but has the same shape, and is manufactured by the same method as the sintered body 5 of the first embodiment.

  And the board | substrate connection process shown in FIG. 5 is performed following a sintered compact arrangement | positioning process. In the manufacturing process of the multilayer printed circuit board 100A of the present embodiment, FIG. 5A is a schematic cross-sectional view showing a state in which a plurality of circuit pattern films are arranged in a multilayer, and FIG. It is a schematic sectional drawing which shows the state which carried out the interlayer connection of the some circuit pattern film arrange | positioned.

  In this substrate connecting step, first, a plurality of third circuit pattern films 30A and 30B (three in this embodiment) and the first circuit pattern film 10A positioned on the uppermost surface are laminated. Then, the third circuit pattern films 30A and 30B on the lower side and the first circuit pattern film 10A on the upper side are laminated with the surface on which the circuit pattern 3A is provided on the lower side, and adjacent to each other. All the circuit pattern films are overlaid so that the circuit pattern 3A of each circuit pattern film enters the lower via hole 4.

  At this time, the circuit pattern 3A of the circuit pattern film 30A is in contact with the sintered body 5A in the via hole 4 formed in the circuit pattern film superimposed below. Then, the upper and lower surfaces of these multilayer printed boards are pressurized while being heated by a vacuum heating press. For example, pressurization is performed for 10 to 20 minutes at a pressure of 1 to 10 MPa under an atmospheric temperature of 250 to 350 ° C.

  By this substrate connection step, the plurality of third circuit pattern films 30A and the first circuit pattern film 10A are integrated by thermal fusion and are adjacent to each other via the sintered body 5A in the via hole 4. A multilayer printed board 100A in which the circuit patterns 3 and 3A of the circuit pattern film are electrically connected to each other is obtained (see FIGS. 5A and 5B).

  In this state, the sintered body 5 </ b> A in the via hole 4 is pressed with a constant force, and is in pressure contact with the surfaces of the circuit patterns 3 and 3 </ b> A constituting the bottom of the via hole 4. Due to this pressure contact state, the Sn component in the sintered body 5A and the Cu component of the copper foil constituting the circuit patterns 3 and 3A are solid-phase diffused to each other at the interface between the sintered body 5A and the circuit patterns 3 and 3A. Since the solid phase diffusion layer is formed, the circuit patterns arranged in multiple layers can be electrically connected.

  As described above, the manufacturing method of the multilayer printed circuit board 100A according to the present embodiment includes the etching step of forming the circuit pattern 3A by etching the thin metal layer 2 formed on the surface of the insulating film 1, and the insulating film 1. A via hole forming step of forming a plurality of via holes 4 which are drilled from the surface opposite to the circuit pattern 3A and reach the circuit pattern 3A, and a set of conductive particles is solidified by sintering, and protrudes from the via hole 4 to the outside. The sintered body disposing step of disposing one sintered body 5A having a size not to be placed in each via hole 4 and the circuit pattern film 30A created in the sintered body disposing step are laminated, and the adjacent circuit pattern film 30A is laminated. By heating and pressing the circuit pattern 3A in contact with the sintered body 5A in the via hole 4, A substrate connecting step of electrically interconnecting a circuit pattern 3A arranged in layers, those comprising a.

  According to this manufacturing method, in addition to the same effects as those of the manufacturing method of the first embodiment, the step of fixing the sintered body 5A in the via hole 4 and the step of electrically connecting the multilayer printed circuit board to each other at the same time are performed simultaneously. Therefore, the manufacturing process can be further simplified and the productivity can be further improved.

(Third embodiment)
In 3rd Embodiment, an example of the manufacturing method of a sintered compact is demonstrated according to FIG. The sintered body manufactured by the method described in the present embodiment can be applied to the method for manufacturing a multilayer printed board according to the present invention. 6 (a) to 6 (d) are schematic views by process showing the manufacturing process of the sintered body in the present embodiment.

The aggregate of conductive particles before the sintering treatment is made into a paste by adding a solvent to Ag (silver) powder and Sn (tin) powder as a dispersant and kneading them. For example, silver powder is composed of silver particles having an average particle diameter of 1 μm and specific surface area of 1.2 m ² / g, tin powder is composed of tin particles having an average particle diameter of 5 μm and specific surface area of 0.5 m ² / g, and the solvent is terpineol. Is used. A resin component such as a dispersant also functions as a binder component that maintains the shape of the entire metal particle. Moreover, it is preferable to make the content rate of the tin particle with respect to the whole electroconductive particle the same as 1st Embodiment, However In this embodiment, the ratio of the content rate of a silver particle and a tin particle shall be 65:35.

  The aggregate of conductive particles (conductive paste 70) produced in this way is a paste using a metal mask 80 in which a plurality of through holes 81 having a predetermined shape (for example, through holes having a depth of 50 μm and an inner diameter of φ100 μm) are formed. The predetermined shape is formed by printing. Specifically, a metal mask 80 in which a predetermined amount of conductive paste 70 composed of tin particles 71, silver particles 73 and solvent 72 satisfying the above-described composition ratio is placed on a substrate 82 (for example, a fluororesin substrate) having releasability. The conductive paste 70 is printed and filled in the through holes 81 of the metal mask 80 (see FIG. 6A).

  When the metal mask 80 is lifted vertically upward from the substrate 82, the substrate 82 has a disk shape having a side surface shape equal to the inner surface shape of the through hole 81 and a height dimension substantially equal to the thickness of the metal mask 80. A plurality of molded conductive pastes 70 remain (see FIG. 6B).

  Subsequently, as shown in FIG. 6 (c), when the conductive paste 70 formed into a disk shape is heated at an atmospheric temperature of 260 ° C. to perform a sintering process, a sintered body 74 having a stable posture is obtained. It is done. This high temperature heating can be performed by a general reflow furnace, a vapor reflow furnace, an atmosphere firing furnace, a box furnace, or the like. The heating atmosphere is preferably a reducing atmosphere to prevent oxidation of the tin component.

  In this sintering process, the conductive paste 70 is in a state where terpineol as a solvent is evaporated and dried, and tin particles and silver particles are mixed. The tin particles having a melting point of 232 ° C. are melted by the heating temperature, and adhere to cover the outer periphery of the silver particles. When heating is continued in this state, the molten tin starts to diffuse from the surface of the silver particles, and a sintered body of tin and silver is generated.

  Next, as shown in FIG. 6 (d), a plurality of sintered bodies 74 are put in a container and washed with a cleaning solution 83, and the sintered body 74 is subjected to a cleaning process for removing carbides. When the washed sintered body 74 is dried, sintered bodies 5 and 5A that can be used in the sintered body arranging step are obtained.

  As described above, the conductive paste 70 produced by mixing conductive particles containing silver powder and tin powder with a solvent is molded into a predetermined shape using a metal mask 80 and then sintered at a high temperature. Sintered bodies 5 and 5A are manufactured by performing cleaning and further cleaning to treat carbide.

According to this method of manufacturing a sintered body, since the sintered body is manufactured by performing paste molding using the metal mask 80, it is reliable from the viewpoint of electrical conductivity and bondability with the circuit pattern connected between the layers. High-performance sintered bodies 5 and 5A can be mass-produced.
(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, a resin film composed of 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin is used as the resin film 2, but the present invention is not limited to this. A film in which a non-conductive filler is filled in an ether ether ketone resin and a polyether imide resin may be used, or polyether ether ketone (PEEK) or polyether imide (PEI) may be used.

  In the above-described embodiment, the multilayer printed circuit boards 100 and 100A are three-layer or four-layer printed circuit boards, but the number of layers is limited to the number of layers as long as the multilayer circuit pattern layer is configured. It is not a thing.

(A)-(e) is sectional drawing according to process which shows the outline of the manufacturing process of the multilayer printed circuit board in 1st Embodiment. (A) And (b) is the schematic which showed the procedure of the sintered compact arrangement | positioning process in the manufacturing process of a multilayer printed circuit board. It is the schematic which showed a mode that the sintered compact arrange | positioned at the via hole was pressurized with a roller. In the manufacturing process of the multilayer printed circuit board of a 1st embodiment, it is a schematic sectional view showing the state where a plurality of circuit pattern films arranged in multiple layers were electrically interlayer-connected. In the manufacturing process of the multilayer printed circuit board according to the second embodiment, (a) is a schematic cross-sectional view showing a state in which a plurality of circuit pattern films are arranged in a multilayer, and (b) is a plurality of arrangements in multiple layers. It is a schematic sectional drawing which shows the state which carried out the interlayer connection of the circuit pattern film electrically. (A)-(d) is the schematic according to process which shows the manufacturing process of the sintered compact in 3rd Embodiment.

Explanation of symbols

1 ... Resin film (insulating substrate)
2 ... Metal layer (conductor)
3, 3A ... circuit pattern 4 ... via hole 5, 5A ... sintered body 30A ... third circuit pattern film 40 ... fourth circuit pattern film (printed circuit board)
70 ... Paste 80 ... Metal mask

Claims (5)

A circuit pattern forming step of forming a circuit pattern (3) on the surface of the insulating substrate (1);
A via hole forming step of forming a plurality of via holes (4) reaching the circuit pattern (3) by drilling the insulating base material (1) from the surface opposite to the circuit pattern (3);
In each via hole (4), a sintered body disposing step of disposing one sintered body (5) formed by consolidating an aggregate of conductive particles by sintering;
A sintered body fixing step of fixing each of the sintered bodies (5) arranged in the sintered body arrangement step in the via hole (4);
A substrate connecting step of electrically connecting the circuit patterns (3) arranged in multiple layers by stacking the printed circuit boards (40) obtained in the sintered body fixing step via the sintered body (5) When,
A method for producing a multilayer printed circuit board, comprising: A circuit pattern forming step of forming a circuit pattern (3A) on the surface of the insulating substrate (1);
A via hole forming step of forming a plurality of via holes (4) reaching the circuit pattern (3A) by drilling the insulating base material (1) from the surface opposite to the circuit pattern (3A);
One sintered body (5A) formed in a size not protruding outside from the via hole (4) by consolidating an aggregate of conductive particles by sintering is disposed one by one in each via hole (4). A sintered body arranging step,
The circuit pattern film (30A) prepared in the sintered body arrangement step is laminated and pressed while being heated, whereby the circuit pattern (3A) and the sintered body (5A) in the adjacent circuit pattern film (30A). ) In the via hole (4) to electrically connect the circuit patterns (3A) arranged in multiple layers,
A method for producing a multilayer printed circuit board, comprising:   The method for producing a multilayer printed board according to claim 1, wherein the conductive particles include silver particles and tin particles.   The method for producing a multilayer printed circuit board according to claim 3, wherein the content ratio of the tin particles to the conductive particles is in the range of 20 to 80% by weight. The sintered body (5, 5A) is formed by molding a paste (70) produced by mixing the conductive particles containing silver powder and tin powder with a solvent into a predetermined shape using a metal mask (80). And then sintering by heating at high temperature,
Furthermore, it manufactures by giving the washing | cleaning which processes a carbide | carbonized_material, The manufacturing method of the multilayer printed circuit board as described in any one of Claim 1 to 4 characterized by the above-mentioned.

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