JP6322075B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

  The present invention relates to a method for producing a multilayer printed wiring board, and in particular, includes a printing process in which a peripheral edge of a circuit substrate is covered with a printing plate and a conductive paste is filled in a conduction hole of the circuit substrate with a printing squeegee. The present invention relates to a method for manufacturing a wiring board.

  In recent years, miniaturization and high functionality of electronic devices have been increasingly promoted, and for this reason, the demand for higher density of printed wiring boards has increased. In view of this, the printed wiring board is increased in density by changing the printed wiring board from a single side to a double-sided or a multilayer printed wiring board having three or more layers.

  In electronic devices such as notebook computers and smartphones that use multilayer printed wiring boards, the amount of information has increased significantly in recent years, and multilayer printed wiring boards are also required to support high-speed and large-capacity communication. Yes. For example, in the case of a notebook personal computer, the transmission speed has shifted to a transmission standard of 6 Gbps from 2010 to 2011, and it is important to reduce transmission loss of high-speed signals even in a multilayer printed wiring board.

  Accordingly, liquid crystal polymers (Liquid Crystal Polymer: LCP) have begun to be applied as interlayer insulating materials for multilayer printed wiring boards. Since the liquid crystal polymer has a low dielectric constant and dielectric loss tangent, dielectric loss is small and transmission loss can be reduced. Moreover, since it has high flexibility, it can cope with bending when it is incorporated into equipment.

  However, the liquid crystal polymer has a larger coefficient of thermal expansion in the thickness direction than an insulating material such as polyimide used in a conventional flexible printed wiring board. For this reason, when using a copper plated through hole that is generally used for interlayer connection, the difference in thermal expansion coefficient between the liquid crystal polymer and copper is large, and it may not be possible to ensure sufficient interlayer connection reliability for temperature cycle tests, etc. I think there is sex.

  Therefore, a proposal has been made to apply a conductive hole using a conductive paste to an interlayer connection instead of a copper plated through hole for a printed wiring board having a liquid crystal polymer as an insulating layer (for example, Patent Document 1). reference).

  In the printing process of filling the conductive paste into the conductive holes, in order to collect and reuse the surplus conductive paste after printing, as shown in FIG. A metal printing plate 200 in which a metal plate 220 having an opening 220a corresponding to the size of the circuit substrate 300 is combined is used. Here, for example, when the dimensions of the circuit substrate 300 are 250 mm wide and 300 mm long, the opening 220a of the metal plate 220 has a width of 240 mm and a length of 290 mm that is smaller by 5 mm than the four sides of the circuit substrate 300. Set to

JP 2011-66293 A.

  However, when the metal plate 220 is formed thicker than a predetermined amount (for example, 1 mm), the printing squeegee (not shown) and the circuit substrate 300 are separated from each other, and as shown in FIG. However, the conductive paste P tends to remain on the circuit substrate 300 without reaching the end of the opening 220a, and the conductive paste P cannot be efficiently collected, resulting in an increase in product cost.

  Furthermore, since the circuit substrate 300 and the printing squeegee are separated from each other, the printing pressure when the printing squeegee spreads and spreads the conductive paste P on the circuit substrate 300 is lowered, as shown in FIG. In addition, there is a problem that a void v is generated in the conduction hole 310 and the yield is deteriorated.

  On the other hand, as shown in FIGS. 8A and 8B, when the metal plate 220 is formed thinner than a predetermined amount (for example, 0.1 mm) and has low rigidity, when the opening 220a is formed large, The waviness w tends to occur around the opening 220a, and the durability of the metal printing plate 200 against repeated printing may be reduced, and the printing stability may be reduced.

  Therefore, a technical problem to be solved in order to efficiently produce a multilayer printed wiring board at low cost arises, and the present invention aims to solve this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is characterized in that the periphery of the circuit substrate is covered with a printing plate, and a conductive paste is laid on the circuit substrate with a printing squeegee. In a method for manufacturing a multilayer printed wiring board including a printing step in which the conductive paste is filled in the conductive holes in the circuit substrate, the printing plate has a larger opening than the circuit substrate in plan view. A frame body portion having a small opening smaller than the circuit base material in plan view, and a resin edging portion disposed on a lower periphery of the large opening, and the printing step includes Positioning and placing the frame body portion on the circuit substrate so that the small opening covers the periphery of the circuit substrate; and the conductive paste through the small opening. Step of spreading on top and filling the hole for conduction with paste; Serial to provide a method for manufacturing a multilayer printed wiring board comprising the steps of collecting the excess of the conductive paste on the trimmed part in the large opening, the.

  According to this configuration, the conductive paste is filled and leveled with a high printing pressure by spreading the conductive paste while the printing squeegee is close to the circuit substrate, so that generation of voids is suppressed. The printing process can be performed with a high yield. In addition, since the printing squeegee guides the conductive paste in the small opening to the border, it is possible to suppress the conductive squeegee from remaining locally on the circuit substrate and to efficiently collect the conductive paste. . Furthermore, the durability of the printing plate is increased and printing can be performed stably by contacting the circuit substrate while the resin-made border portion in contact with the circuit substrate remains flat without undulation.

  A second aspect of the present invention provides the method for producing a multilayer printed wiring board according to the first aspect of the present invention, wherein the frame body portion and the edging portion are bonded via an adhesive portion.

  According to this structure, even if it is a case where an edge part is damaged because the edge part is stuck to the frame part via the sticking part, the edge part is peeled off from the frame part, and it exchanges. As a result, since the frame portion can be used, the cost required for the printing process can be reduced.

  According to a third aspect of the present invention, there is provided the method for producing a multilayer printed wiring board according to the second aspect, wherein the sticking portion is a double-sided tape for sticking the frame body portion and the border portion over the entire surface. I will provide a.

  According to this configuration, since the adhering area between the frame body portion and the edging portion is secured according to the size of the double-sided tape, the edging portion is firmly attached to the frame body portion. Durability increases and printing can be performed stably.

  Invention of Claim 4 provides the manufacturing method of the multilayer printed wiring board which is the single-sided tape which adheres the periphery of the said edge part, and the said frame part in the invention of Claim 2 in the invention of Claim 4. To do.

  According to this configuration, since the periphery of the edging part is attached to the frame part via the single-sided tape, the edging part is easily peeled off when the edging part is replaced. can do.

  A fifth aspect of the present invention provides a method for manufacturing a multilayer printed wiring board according to any one of the first to fourth aspects, wherein the thickness of the frame body is set to 0.5 mm or more. .

  According to this configuration, by ensuring the rigidity of the frame body portion, the occurrence of waviness around the large opening of the frame body portion is suppressed, the durability of the printing plate is increased, and stable printing is performed. be able to.

  A sixth aspect of the present invention provides the method for producing a multilayer printed wiring board according to any one of the first to fifth aspects of the present invention, wherein the edge portion has a thickness set to 0.1 mm or less.

  According to this configuration, since the printing squeegee and the circuit base material approach according to the thickness of the edging portion, generation of voids in the hole for conduction is suppressed, the yield of the printing process is improved, and surplus The conductive paste can be efficiently collected.

  A seventh aspect of the present invention provides the method for producing a multilayer printed wiring board according to any one of the first to sixth aspects, wherein the frame body portion is made of stainless steel or aluminum.

  According to this configuration, by ensuring the rigidity of the frame body portion, the occurrence of waviness around the large opening of the frame body portion is suppressed, the durability of the printing plate is increased, and stable printing is performed. be able to.

  The invention according to claim 8 provides the method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 7, wherein the border portion is made of PET, PEN, polyimide or LCP.

  According to this configuration, the edge portion can be obtained at a low cost, and the workability is excellent and the replacement at the time of breakage is facilitated. Therefore, the cost required for the edge portion replacement can be reduced.

  A ninth aspect of the present invention provides the method for producing a multilayer printed wiring board according to any one of the first to seventh aspects, wherein the border is formed by laminating PET, PEN, polyimide, or LCP. .

  According to this configuration, the edge portion can be obtained at a low cost, and the workability is excellent and the replacement at the time of breakage is facilitated. Therefore, the cost required for the edge portion replacement can be reduced.

  In the present invention, the conductive paste is filled in the hole for conduction with a high printing pressure, and the surplus conductive paste is efficiently recovered and the printing plate can be used repeatedly. Can be manufactured.

It is a schematic diagram which shows a part of procedure of the manufacturing method of the multilayer printed wiring board which concerns on one Example of this invention, (a) is a figure which shows a circuit base material, (b) is a circuit base material. It is a figure which shows the state which formed the hole for conduction | electrical_connection, (c) is a figure which shows the state which filled the hole for conduction | electrical_connection with the electrically conductive paste. It is a schematic diagram which shows a part of procedure of the manufacturing method of the multilayer printed wiring board which concerns on one Example of this invention, (a) is a figure which shows a circuit base material, (b) is a circuit base material. It is a figure which shows the state which formed the hole for conduction | electrical_connection, (c) is a figure which shows the state which filled the hole for conduction | electrical_connection with the electrically conductive paste. It is a figure which shows a part of procedure of the manufacturing method of the multilayer printed wiring board based on one Example of this invention, (a) is the circuit base material obtained by FIG.1 (c), and FIG.2 (c). It is a figure which shows the state before adhere | attaching the obtained circuit base material, (b) is a figure which shows the state which laminated | stacked the circuit base material, (c) is a figure on both surfaces of a circuit base material. The figure which shows the state formed. It is a figure which shows the printing plate used with the manufacturing method of the multilayer printed wiring board concerning this invention, (a) is a top view of a printing plate, (b) is the IV-IV line | wire end surface of Fig.4 (a) Figure. It is a figure which shows the modification of the printing plate used with the manufacturing method of the multilayer printed wiring board concerning this invention, (a) is a top view of a printing plate, (b) is V- of FIG. V line end view. It is a schematic diagram which shows a printing process, (a) is a figure which shows the state which mounts a printing plate on a circuit base material, (b) is a figure which shows the state before spreading | pasting and leveling a conductive paste with a printing squeegee. (C) is a figure which shows the state which spreads the conductive paste with a printing squeegee, and (d) is a figure which shows the state which collected the excess conductive paste. It is a figure which shows the printing plate used with the manufacturing method of the conventional multilayer printed wiring board, (a) is a top view of a printing plate, (b) is the end surface of the VIIB-VIIB line | wire in Fig.7 (a) It is a figure, (c) is the VIC part enlarged view in FIG.7 (b). It is a figure which shows the printing plate used with the manufacturing method of the conventional multilayer printed wiring board, (a) is a top view of a printing plate, (b) is the VIIIB-VIIIB line | wire end view of Fig.8 (a) , (C) is an end view taken along line VIIIC-VIIIC in FIG.

  In order to achieve the object of producing a multilayer printed wiring board inexpensively and efficiently, the method for producing a multilayer printed wiring board according to the present invention covers the periphery of a circuit substrate with a printing plate, and uses a printing squeegee to circuit the substrate. In a method of manufacturing a multilayer printed wiring board including a printing process in which a conductive paste is spread and leveled and a conductive paste is filled in a conductive hole of a circuit board, the printing plate is larger than the circuit board in plan view. A frame body portion having an opening portion, and a resin rim portion having a small opening portion smaller than the circuit substrate in plan view and disposed on the lower peripheral edge of the large opening portion. Positioning and placing the frame on the circuit board so that the opening covers the periphery of the circuit board, and conducting and spreading the conductive paste on the circuit board through the small opening The process of filling the common holes with paste, and the extra space on the border in the large opening A step of collecting the conductive paste was achieved by including.

  Hereinafter, a method for manufacturing a multilayer printed wiring board according to an embodiment of the present invention will be described with reference to the drawings.

  First, a pair of circuit base materials 10 and 20 are prepared. As shown in FIG. 1A, one circuit substrate 10 includes a flexible insulating base material 11, a copper foil 12 covering one side surface of the flexible insulating base material 11, and a flexible insulating base. And a laminating adhesive 13 and a mask film 14 that cover the other side surface of the material 11.

  The flexible base material 11 is made of LCP having a thickness of 50 μm. Moreover, the thickness of the copper foil 12 is set to 12 μm. The laminating adhesive 13 is an epoxy adhesive having a thickness of 15 μm. The mask film 14 is made of 20 μm thick PET (polyethylene terephthalate). The mask film 14 is used as a printing mask in a printing process by forming a hole through which the conductive paste is transmitted above the conduction hole 15 when the conduction hole 15 described later is formed.

  Next, as shown in FIG. 1B, the circuit substrate 10 is subjected to laser processing and desmear treatment to form a conduction hole 15. For the laser processing, for example, a carbon dioxide laser with high productivity is preferably used.

  Next, as illustrated in FIG. 1C, the conductive paste P is filled into the conduction holes 15 through a printing process using a printing plate described later. Here, the conductive paste P is obtained by mixing metal particles such as copper particles and silver particles in a resin binder such as epoxy. Since the surface of the circuit substrate 10 is covered with the mask film 14, it is possible to avoid the conductive paste P that causes a short circuit failure from adhering to the surface of the laminating adhesive 13, and to conduct the conductive hole 15. The active paste P can be filled.

  As shown in FIG. 2A, the other circuit substrate 20 includes a flexible insulating base material 21, a copper foil 22 covering one side surface of the flexible insulating base material 21, and a flexible insulating base. And a mask film 23 that covers the other side surface of the material 21. The flexible insulating base material 21 is the same as the flexible insulating base material 11 described above, and the copper stay 22 is the same as the copper stay 12 described above.

  The mask film 23 is made of 18 μm PET, and is bonded to the flexible insulating base material 21 via a 7 μm thick easily peelable adhesive (not shown). The mask film 23 is used as a printing mask in a printing process by forming a hole through which the conductive paste is transmitted above the conduction hole 15 when the conduction hole 24 described later is formed.

  Next, as shown in FIG. 2B, the circuit substrate 20 is subjected to laser processing and desmear processing to form a conduction hole 24. For the laser processing, for example, a carbon dioxide laser with high productivity is preferably used.

  Next, as shown in FIG. 2C, the conductive paste P is filled into the conduction holes 24 through a printing process using a printing plate described later.

In addition, the flexible base materials 11 and 21 mentioned above can change a thickness and material suitably according to a use. For example, a flexible base material used for a thin substrate may be made of polyimide having a thickness of 12 μm.
Further, the thickness of the copper stays 12 and 22 is not limited to the above-described thickness, and a thinner one such as 9 μm can be selected according to the pattern width of the copper wiring.
The thickness of the lamination adhesive 13 can be changed according to the application. For example, a thin adhesive such as 10 μm can be selected as the lamination adhesive used for the thin substrate.
Furthermore, the thickness of the mask films 14 and 23 can be changed depending on the application, and affects the rivet height formed after printing. In order to reduce the thickness, a thin one such as a thickness of 16 μm can be selected.

  When laminating the pair of circuit substrates 10 and 20, first, the mask films 14 and 23 are removed. Thereby, the conductive paste P remaining on the mask films 14 and 23 is peeled off, and the conductive paste P is suppressed from adhering to the lamination adhesive 13.

  And as shown to Fig.3 (a), the circuit base materials 10 and 20 are positioned so that the rivet of the paste P1 and 2 may oppose. Next, as illustrated in FIG. 3B, the pair of circuit base materials 10 and 20 are fixed by a vacuum press or the like via the lamination adhesive 13, thereby obtaining the multilayer circuit base material 30. And as shown in FIG.3 (c), pattern pa is formed in both surfaces of the multilayer circuit base material 30 by a normal photofabrication method. Thereafter, surface treatment such as solder plating, nickel plating, gold plating, or the like is performed on the surface of the substrate as necessary, and a photo solder resist layer is formed and external processing is performed to obtain a multilayer printed wiring board.

  Next, the printing plate used in the printing process will be described. In the following description, the circuit substrate 10 will be described as an example, but it is needless to say that the circuit substrate 20 is the same.

  As shown in FIGS. 4A and 4B, the printing plate 100 includes a frame body portion 110 having a large opening portion 110a, and an edge portion 120 disposed on the lower peripheral edge of the opening portion 110a. Yes.

The frame body portion 110 includes a plate frame 111 and a metal plate 112 in which a large opening portion 110a is formed.
The large opening 110a is formed larger than the circuit substrate 10 in plan view. In this embodiment, the large opening 110a is set to have a width of 340 mm and a length of 390 mm.

  The thickness of the metal plate 112 is preferably set to 0.5 mm or more, and is set to 2 mm in this embodiment. Thereby, the wave | undulation of the metal plate 112 can be suppressed, ensuring the magnitude | size of the large opening part 110a. The metal plate 112 may be made of any material as long as it has such a rigidity that no swell is generated in the state where the large opening 110a is formed. For example, stainless steel or aluminum is preferable. In this embodiment, the metal plate 112 is made of stainless steel. The thickness and material of the metal plate 112 are not limited to 2 mm and stainless steel, respectively, and are appropriately selected according to the size of the plate frame 111 and the opening 110a within a range in which the undulation of the metal plate 112 is suppressed. It is what is done.

  The rim portion 120 includes a small opening 120a that is smaller than the circuit substrate 10 in plan view. The small opening 120a is formed to have a width of 240 mm and a length of 290 mm by laser processing or the like.

  The thickness of the rim portion 120 is preferably set to 0.1 mm or less, and is set to 0.1 mm in this embodiment. Thereby, the printing squeegee is arranged in a state of approaching the circuit substrate 10. The material of the rim portion 120 is preferably a material that is solvent resistant to the conductive paste P and softer than the squeegee used, and is made of PET in this embodiment. For example, when a polyurethane squeegee is used as a printing squeegee, 0.1 mm thick PET, PEN (polyethylene naphthalate), polyimide, LCP, etc. are used alone, or at least two or more of these are laminated. May be used. Such an edge portion 120 is cheaper and more workable than the metal plate 112, and therefore can be easily replaced when damaged.

  The rim portion 120 is attached to the frame 110 via a double-sided tape 130. The rim portion 120 is firmly fixed in accordance with the bonding area between the rim portion 120 and the double-sided tape 130. Thereby, even if the edging part 120 is damaged, the printing plate 100 can be used repeatedly by exchanging only the edging part 120.

  In addition, as shown in FIGS. 5A and 5B, the sticking portion may be a single-sided tape 131 that fixes the periphery of the edge portion 120 to the frame body portion 110. Thereby, the edge part 120 can be easily removed from the frame part 110 when the edge part 120 is replaced. The single-sided tape 131 is preferably selected to be thinner than the circuit base material. In this embodiment, the single-sided tape is made of polyimide having a thickness of 60 μm.

Next, a printing process using the printing plate 100 will be described.
First, the circuit substrate 10 is placed on a chuck table (not shown) so that the conduction hole 15 opens upward, and is vacuum-adsorbed and fixed to the chuck table. Thereafter, as shown in FIG. 6A, the printing plate 100 is placed on the circuit substrate 10. When the printing plate 100 is positioned at a predetermined position on the circuit substrate 10, the large opening 110 a is arranged so as to surround the circuit substrate 10, and the small opening 120 a Arranged to cover. Thereby, the conduction hole 15 of the circuit substrate 10 is exposed to the outside through the opening 110a and the opening 120a.

  The conductive paste P is put into the opening 110a, and the printing squeegee S moves from one end to the other end of the large opening 110a while spreading the paste P on the circuit base material 10, so that the conductive The conductive paste P is filled in the conduction holes 15 of the printing plate 100. As the rim 120 is formed thin and the printing squeegee S and the circuit substrate 10 approach each other, the conductive paste P is filled into the conduction hole 15 with an appropriate printing pressure.

  As shown in FIG. 6D, when the printing squeegee S moves to the other end of the large opening 110a, excess conductive paste P is collected on the border 120. At this time, the margin 120 is formed thin, and the conductive paste P is spread and leveled while the printing squeegee S is close to the circuit substrate 10, so that the excess conductive paste P is locally applied on the circuit substrate 10. Accumulation is suppressed.

  In addition, after filling the conductive paste P into the conduction hole 15, the conductive paste P remaining on the circuit substrate 10 can be further removed by using a scraper (not shown) harder than the squeegee. Specifically, the surplus conductivity is obtained by moving the scraper from the other end of the opening 110a toward the one end and scraping off the conductive paste P remaining on the surface of the mask film 14 of the circuit substrate 10. The paste P can be reliably recovered.

  Thus, the method for manufacturing a multilayer printed wiring board according to the present invention spreads the conductive paste P while the printing squeegee is close to the circuit substrate 10 so that the conductive paste P has a high printing pressure. Since the hole 15 for conduction is filled, generation of voids is suppressed and the printing process can be performed with a high yield. Moreover, since it is suppressed that the electrically conductive paste P remains locally on the circuit base material 10, the electrically conductive paste P can be collect | recovered efficiently. Furthermore, the resin border 120 in contact with the circuit substrate 10 can be stably printed by coming into contact with the circuit substrate 10 without being wavy. Thereby, a multilayer printed wiring board can be manufactured cheaply and efficiently.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 10 ... Circuit base material 11 ... Flexible insulating base material 12 ... Copper foil 13 ... Laminating adhesive 14 ... Mask film 15 ... Conduction hole 20 ... Circuit base Material 21 ... Flexible insulating base material 22 ... Copper foil 23 ... Mask film 24 ... Hole for conduction 30 ... Multilayer circuit substrate 100 ... Printing plate 110 ... Frame 110a ... Large opening 111 ... Plate frame 112 ... Metal plate 120 ... Border 120a ... Small opening 130 ... Double-sided tape (sticking part)
131 ... Single-sided tape (sticking part)
P ... conductive paste S ... printing squeegee

Claims (9)

Multi-layer printing including a printing step of covering a peripheral edge of a circuit substrate with a printing plate, spreading a conductive paste on the circuit substrate with a printing squeegee, and filling the conductive paste in a conduction hole of the circuit substrate In the method of manufacturing a wiring board,
The printing plate is
A frame portion having a larger opening than the circuit substrate in plan view;
A resin rim having a small opening smaller than the circuit substrate in plan view and disposed on the lower periphery of the large opening;
With
The printing process includes
Positioning and placing the frame body portion on the circuit substrate so that the small opening covers the periphery of the circuit substrate; and
Spreading the conductive paste on the circuit substrate through the small openings and filling the conductive paste into the conductive holes;
Collecting excess of the conductive paste on the border within the large opening;
A method for producing a multilayer printed wiring board, comprising:   The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the frame body part and the border part are attached via an attaching part.   3. The method for manufacturing a multilayer printed wiring board according to claim 2, wherein the sticking part is a double-sided tape that sticks the frame part and the border part over the entire surface.   The method for producing a multilayer printed wiring board according to claim 2, wherein the sticking part is a single-sided tape that sticks a peripheral edge of the border part and the frame part.   The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 4, wherein the thickness of the frame body is set to 0.5 mm or more.   The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 5, wherein a thickness of the border portion is set to 0.1 mm or less.   The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the frame body is made of stainless steel or aluminum.   The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 7, wherein the border portion is made of PET, PEN, polyimide, or LCP.   The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 7, wherein the border portion is formed by laminating PET, PEN, polyimide, or LCP.