KR20040093258A - Method of manufacture for multi-layered printed circuit board - Google Patents

Abstract

PURPOSE: A method is provided to increase the contact area of a laser via hole, and achieve improved electrical contact and bonding characteristics with the electronic component mounted on a multi-layer printed circuit board. CONSTITUTION: A method comprises a step of forming a multi-layer substrate by stacking a plurality of metal layers and insulation resin layers on a double-sided substrate(101); a step of forming a plurality of laser via holes on the multi-layer substrate; a step of forming a first metal layer(103a) on the resultant structure; a step of filling the laser via holes with a conductive paste ink having a copper content of 30 to 40%, and flattening the resultant structure in such a manner that the first metal layer is exposed; a step of forming a second metal layer(107a) on the resultant structure; and a step of exposing the top insulation resin layer of the multi-layer substrate by patterning certain parts of the first and second metal layers between the laser via holes and the top metal layer of the multi-layer substrate, and forming a solder resist layer(116) on the resultant structure.

Description

METHODS OF MANUFACTURE FOR MULTI-LAYERED PRINTED CIRCUIT BOARD

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer printed circuit board (PCB), and in particular, fills and planarizes a filler in a laser via hole formed in a multilayer printed circuit board, and then forms a second conductor layer thereon, thereby contacting the laser via hole. The present invention relates to a method for manufacturing a multilayer printed circuit board having broadened, improved electrical contact and bonding characteristics with components mounted on the multilayer printed circuit board, and improved reinforcement and soldering characteristics of the via pads.

In general, a printed circuit board is coated with copper foil on an epoxy-based insulated substrate, and may be classified into a single-sided printed circuit board, a double-sided printed circuit board, a multilayer printed circuit board, and the like.

The single-sided printed circuit board has a structure in which copper foil of a wiring pattern is coated on only one side of the insulated substrate, and the double-sided printed circuit board has a structure in which copper foil of a wiring pattern is coated on both sides of the insulated substrate. The substrate has a structure in which a plurality of single-sided printed circuit boards or double-sided printed circuit boards are stacked.

As the multilayer printed circuit board has recently been reduced in size and thinness, a ball grid array (BGA), chip scale packaging (CSP), and a multi-chip module such as a mobile phone, a PCS, an IMT 2000, a notebook, a palmtop, a camcorder, etc. It is widely applied to semi-metal package substrates such as multi chip module (MCM).

Next, a manufacturing process of a conventional printed circuit board will be described with reference to the accompanying drawings.

1A to 1W are cross-sectional views illustrating a manufacturing process of a multilayer printed circuit board according to the prior art.

In the manufacturing process of the multilayer printed circuit board, first, as shown in FIG. 1A, a mechanical drill is applied to a double-sided board 1 on which upper and lower copper foils 1b and lower copper foils 1c are formed on and under the insulating plate 1a. To form the buried via hole (2).

Then, as illustrated in FIG. 1B, the double-sided substrate 1 on which the buried via hole 2 is formed is plated (at least one or more times) to form an inner circumferential surface of the buried via hole 2 and the double-sided substrate. The first metal layer 3 is formed above and below (1). At this time, the first metal layer 3 mainly uses copper.

Then, as shown in FIG. 1C, the buried via hole 2 in which the first metal layer 3 is formed is filled with a filler 4 using a jig 30. . At this time, the filler 4 uses a resin (Resin) conductive material.

Then, as shown in FIG. 1D, the filler 4 is cured at a constant temperature (eg, 150 ° C.) and for a predetermined time (eg, 50 minutes).

Next, as shown in FIG. 1E, the chemical mechanical polishing (CMP) is performed such that the first metal layer 3 is exposed to the filler 4 protruding from the upper and lower portions of the double-sided substrate 1. Planarization 4a using.

Next, as shown in FIG. 1F, a first photoresist layer 5 is disposed on and under the double-sided substrate 1 on which the first metal layer 3 and the filler 4a are exposed. Form.

Next, as shown in FIG. 1G, the first photoresist layer 5 is patterned 5a to pattern the first metal layer 3. At this time, the first photoresist layer 5 is a negative resist layer 5a.

Then, as shown in FIG. 1H, the first metal layer 3 is exposed to light on the patterned first photoresist layer 5a to expose the upper copper foil 1b and the lower copper foil 1c. Etch

Next, as illustrated in FIG. 1I, the first metal pattern layer 3a is formed on the double-sided substrate 1 by removing the first photoresist layer 5a.

As described above, by repeatedly performing the processes illustrated in FIGS. 1A to 1I, a multilayer substrate having a multilayer metal pattern may be formed.

Next, as shown in FIG. 1J, first insulating resin layers 6 are formed on upper and lower portions of the double-sided substrate 1 on which the first metal pattern layer 3a is formed, and the first insulating resin is formed. The second metal layer 7 is formed on the ground layer 6 by high temperature and high pressure. In this case, the second metal layer 7 uses copper, and the first insulating resin layer 6 and the second metal layer 7 are referred to as a first resin coated copper foil (RCC) layer.

Next, as shown in FIG. 1K, a second photoresist layer 8 is formed on and under the double-sided substrate 1 on which the second metal layer 7 is formed.

Next, as shown in FIG. 1L, the second photoresist layer 8 is patterned 8a to pattern the second metal layer 7. At this time, the second photoresist layer 8 is a negative resist layer 8a.

Next, as shown in FIG. 1M, the second metal layer 7 is etched so that the first insulating resin layer 6 is exposed by irradiating light onto the second photoresist film 8a so as to expose the second metal layer 7. The pattern layer 7a is formed. Next, although not shown in the figure, the second photoresist layer 8a is removed.

Next, as shown in FIG. 1N, second insulating resin layers 9 are formed on upper and lower portions of the double-sided substrate 1 on which the second metal pattern layer 7a is formed, and the second insulating resin is formed. The third metal layer 10 is formed on the ground layer 9 by high temperature and high pressure. In this case, the third metal layer 10 is a metal layer using copper, and the second insulating resin layer 9 and the third metal layer 10 are referred to as a second resin coated copper foil (RCC) layer.

Next, as shown in FIG. 1O, the third photoresist layer 11 is formed on and under the double-sided substrate 1 on which the third metal layer 10 is formed.

Next, as shown in FIG. 1P, the third photoresist layer 11 is patterned 11a to pattern the third metal layer 10. At this time, the third photoresist layer 11a is a negative resist layer 11a.

Next, as illustrated in FIG. 1Q, the third metal layer 10 is etched by irradiating light onto the patterned third photoresist film 11a to expose the second insulating resin layer 9. 3 metal pattern layer 10a is formed. Next, although not shown in the figure, the third photoresist layer 11a is removed. The second insulating resin layer 9 exposed by the third metal pattern layer 10a is a laser point for forming a laser via hole formed in a subsequent process.

Next, as shown in FIG. 1R, the first insulation exposed by the second insulating resin layer 9 and the second metal pattern layer 7a exposed by the third metal pattern layer 10a. The insulating resin layer 6 is removed with a laser drill to expose a predetermined portion of the first metal pattern layer 3a to form a first laser via hole 13a. In addition, the second insulating resin layer 9 exposed by the third metal pattern layer 10a is removed by a laser drill so that a predetermined portion of the second metal pattern layer 7a is exposed. 13b). At this time, the laser drill is an etching equipment for removing the insulating layer by irradiating a laser beam using a high-pressure carbon dioxide (Co ₂ ) gas.

As described above, a laser via hole for interlayer electrical connection of the multilayer substrate formed by the process of FIGS. 1A to 1I is formed by the process illustrated in FIGS. 1J to 1R.

Next, as shown in FIG. 1S, the fourth metal layer 14 is formed by performing panel plating on the upper and lower portions of the double-sided substrate 1 on which the first and second laser via holes 13a and 13b are formed. Form.

Next, as shown in FIG. 1T, a fourth photoresist layer 15 is formed on the structure on which the fourth metal layer 14 is formed.

Next, as shown in FIG. 1U, the fourth photoresist layer 15 is patterned 15a to pattern the fourth metal layer 14. At this time, the fourth photoresist layer 15a is a negative resist layer 15a.

Next, as shown in FIG. 1V, the fourth metal layer 14 is etched by irradiating light onto the patterned fourth photoresist film 15a to expose the third metal pattern layer 10a. 4 Metal pattern layer 14a is formed.

Next, as shown in FIG. 1W, the third metal pattern layer 10a is etched to expose the second insulating resin layer 9, and then the fourth photoresist layer 15a is removed. Next, screen printing is performed on the exposed second insulating resin layer 9 to form a solder resist layer 16.

As described above, the laser via hole formed by the process of FIGS. 1J to 1R is plated by the process illustrated in FIGS. 1S to 1W to form an external pattern for power distribution.

2A and 2B are enlarged views of a laser via hole photograph of a printed circuit board completed by a conventional manufacturing process and a partial region A of the photograph.

3 is a cross-sectional view of a laser via hole of a printed circuit board completed by a conventional manufacturing process.

Referring to FIGS. 2A, 2B, and 3, a technical problem of a printed circuit board completed by the prior art is described. The conventional laser via hole has a small contact area with various microelectronic components, and thus, the electronic component and the laser via hole are smaller. Due to the structure that reduces the bonding properties of the electronic component, the electronic component may not be correctly mounted and bonded to the laser via hole, thereby reducing the reliability of the multilayer printed circuit board. Due to the formation of solder balls, there was a problem such as a short between the parts and the solder balls.

In addition, the bonding strength decreases due to the flow of cream during solder solder due to the adjacent laser via hole when soldering to the via pad, and the ink Ink during screen printing is generated. For this reason, there is a problem in that plating defects occur and soldering defects occur during gold plating of the SMD pads.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, by filling and flattening a filler in a laser via hole formed in a multilayer printed circuit board and forming a second conductive layer thereon, thereby widening the contact area of the laser via hole. The present invention provides a method of manufacturing a multilayer printed circuit board having improved electrical contact and bonding characteristics with components mounted on the multilayer printed circuit board, and improved reinforcement and soldering characteristics of the via pads.

In addition, another object of the present invention is to prevent the separation of the filler and the conductor layer at a high temperature by using the same material for the filler filled in the laser via hole of the multilayer printed circuit board and the conductor layer formed thereon. The present invention provides a method for manufacturing a multilayer printed circuit board.

In addition, another object of the present invention is to deform even at high temperature by using the ink (Ink) of 30-40% copper content of the copper paste in the filler filled in the laser via hole of the multilayer printed circuit board The present invention provides a method of manufacturing a multilayer printed circuit board having excellent conductivity, excellent conductivity, strong durability, and thin and short product.

1A to 1W are cross-sectional views of a manufacturing process of a multilayer printed circuit board according to the related art.

2A and 2B are photographs showing a laser via hole of a multilayered printed circuit board completed by a conventional manufacturing process, and an enlarged photograph showing a portion A of the photograph.

3 is a cross-sectional view of a laser via hole of a multilayer printed circuit board completed by a conventional manufacturing process.

Figure 4a to 4z is a cross-sectional view of the manufacturing process of the multilayer printed circuit board according to the present invention

5A and 5B are photographs showing a laser via hole of a multilayered printed circuit board completed by the manufacturing process of the present invention, and an enlarged photograph showing a portion B of the photograph.

6 is a cross-sectional view of the laser via hole of the multilayer printed circuit board completed by the manufacturing process of the present invention.

7A and 7B are enlarged cross-sectional views of a conductive paste ink having a copper content of 0 to 29% by plugging printing into SBL and MBL laser via holes.

7C to 7H are enlarged photographs and cross-sectional views for explaining the problems of SBL and MBL laser vias using conductive paste inks having a copper content of 0 to 29%.

8A and 8B are enlarged cross-sectional views of a conductive paste ink having a copper content of 30 to 40% by plugging printing into SBL and MBL laser via holes.

8C to 8H are enlarged photographs and cross-sectional views for explaining the state of SBL and MBL laser vias using conductive paste inks having a copper content of 30 to 40%.

9A and 9B are enlarged cross-sectional views of a conductive paste ink having a copper content of 41 to 100% by plugging printing to SBL and MBL laser via holes.

9C to 9H are enlarged photographs and cross-sectional views for explaining problems of SBL and MBL laser vias using conductive paste inks containing 41 to 100% copper.

10A is a photograph of the surface when the copper particle size of the conductive paste ink is 20 μm or less (≦ 20 μm)

10B and 10C are enlarged cross-sectional views of SBL and MBL laser vias when the copper particle size of the conductive paste ink is 20 μm or less (≦ 20 μm).

10D is a photograph of the surface when the copper particle size of the conductive paste ink is 21 μm or more and 50 μm or less (21 μm ≦ particle size ≦ 50 μm)

10E and 10F are enlarged cross-sectional views of SBL and MBL laser vias with a copper particle size of 21 μm or more and 50 μm or less (21 μm ≦ particle size ≦ 50 μm) of the conductive paste ink.

<Explanation of symbols for the main parts of the drawings>

101: double-sided substrate 101a: insulating plate

101b: upper copper foil 101c: lower copper foil

102: buried via hole 103, 103a: first metal layer

104: filling material

105, 105a: first photoresist layer 106: first insulating resin layer

107, 107a: second metal layer

108, 108a: second photoresist layer

109, 109a: second insulating resin layer 110, 110a: third metal layer

111, 111a: third photoresist layer

113a: first laser via hole 113b: second laser via hole

114: fourth metal layer

115, 115a: fourth photoresist layer 116: solder resist layer

120, 120a: Filler 121, 121a: Fifth metal layer

Method of manufacturing a multilayer printed circuit board according to the present invention for achieving the above object,

Stacking a plurality of metal layers and insulating resin layers on a double-sided substrate on which buried via holes are formed to form a multi-layer substrate;

Forming a plurality of laser via holes in the multilayer substrate;

Forming a first metal layer over the structure;

Filling the plurality of laser via holes in which the first metal layer is formed with conductive paste ink having a copper content of 30 to 40% and then planarizing the first metal layer to be exposed;

Forming a second metal layer over the structure; And

And partially patterning the first and second metal layers between the laser via hole and the laser via hole and the uppermost metal layer of the multilayer substrate to expose the uppermost insulating resin layer of the multilayer substrate, and then forming a solder resist layer. It features.

The first metal layer may include any one of gold, silver, copper, aluminum, a conductor, a conductive resin, a conductive paste ink containing copper, and a resin containing copper.

The conductive paste ink is a conductive paste ink having a copper content of 30 to 40%.

The particle size of copper contained in the conductive paste ink is characterized in that it has a 20㎛ or less.

The coating film height of the conductive paste ink is 60 μm, and the coating film width of the conductive paste ink is 480 to 500 μm.

And filling the laser via hole with the conductive paste ink and then curing the laser via hole at a predetermined temperature and for a predetermined time before planarization.

The curing process is characterized in that the curing for 20 minutes at a temperature of 150 ℃.

The curing process is dried using a conveyor dryer having first to sixth chambers, wherein the first chamber is 150 ° C, the second chamber is 165 ° C, and the third to sixth chambers are stepwise at 175 ° C. It is characterized by curing.

In the planarization of the conductive paste ink, a ceramic brush is used.

The second metal layer is characterized in that it comprises any one of gold, silver, copper, aluminum, conductive conductor, conductive resin, conductive paste ink containing copper, copper containing resin.

The conductive paste ink is a conductive paste ink having a copper content of 30 to 40%.

The particle size of copper contained in the conductive paste ink is characterized in that it has a 20㎛ or less.

The manufacturing method of the multilayer printed circuit board may include forming a photoresist layer on the second metal layer; Forming a photoresist pattern layer using the photoresist layer using a mask pattern for forming the solder resist layer; And etching the first and second metal layers and the top metal layer of the multi-layer substrate using the photoresist pattern layer as a barrier layer to expose the top insulating resin layer of the multi-layer substrate.

The solder resist layer is formed by a screen printing process.

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

4A to 4Z are cross-sectional views illustrating a manufacturing process of a multilayer printed circuit board according to the present invention.

In the manufacturing process of the multilayer printed circuit board, first, as shown in FIG. To form the buried via hole 102.

Next, as shown in FIG. 4B, the double-sided substrate 101 on which the buried via hole 102 is formed is plated (at least one or more times) to form an inner circumferential surface of the buried via hole 102 and the double-sided substrate. The first metal layer 103 is formed on the upper portion and the lower portion of the 101. In this case, the first metal layer 103 includes gold, silver, copper, a conductive resin, a metal or resin plated with copper, and mainly copper.

Next, as shown in FIG. 4C, the buried via hole 102 in which the first metal layer 103 is formed is filled using a filler 104 using a jig 130. . At this time, the filler 104 uses one of silver paste, copper paste, and conductive resin.

Next, as shown in FIG. 4D, the filler 104 is cured at a constant temperature (eg, 150 ° C.) and a predetermined time (eg, 50 minutes).

Next, as shown in FIG. 4E, chemical mechanical polishing (CMP) is performed to expose the first metal layer 103 to the filler 104 protruding from the upper and lower portions of the double-sided substrate 101. The process is planarized 104a.

Next, as shown in FIG. 4F, a first photoresist layer 105 is disposed on the upper and lower portions of the double-sided substrate 101 on which the first metal layer 103 and the filler 104a are exposed. Form.

Next, as shown in FIG. 4G, the first photoresist layer 105 is patterned 105a to pattern the first metal layer 103. In this case, the first photoresist layer 105 is a negative resist layer.

Next, as shown in FIG. 4H, the first metal layer 103 is irradiated with light on the patterned first photoresist layer 105a to expose the upper copper foil 101b and the lower copper foil 101c. Etch to form the first metal pattern layer 103a.

Next, as shown in FIG. 4I, the first metal pattern layer 103a is formed on the double-sided substrate 101 by removing the first photoresist layer 105a.

Next, as shown in FIG. 4J, first insulating resin layers 106 are formed on upper and lower portions of the double-sided substrate 101 on which the first metal pattern layer 103a is formed, and the first insulating resin is formed. The second metal layer 107 is formed on the ground layer 106 by high temperature and high pressure. In this case, the second metal layer 107 includes gold, silver, copper, a conductive resin, a metal plated with copper or a resin, and mainly copper. The first insulating resin layer 106 and the second metal layer 107 are referred to as a first resin coated copper foil (RCC) layer.

Next, as shown in FIG. 4K, a second photoresist layer 108 is formed on and under the double-sided substrate 101 on which the second metal layer 107 is formed.

Next, as shown in FIG. 4L, the second photoresist layer 108 is patterned 108a to pattern the second metal layer 107. In this case, the second photoresist layer 108 is a negative resist layer.

Next, as shown in FIG. 4M, the second metal layer 107 is etched so that the first insulating resin layer 106 is exposed by irradiating light on the second photoresist film 108a to expose the second metal layer 107. After the pattern layer 107a is formed, the second photoresist layer 108a is removed.

Next, as shown in FIG. 4N, second insulating resin layers 109 are formed on upper and lower portions of the double-sided substrate 1 on which the second metal pattern layer 107a is formed, and the second insulating resin is formed. The third metal layer 110 is formed on the ground layer 109 by high temperature and high pressure. In this case, the third metal layer 110 includes gold, silver, copper, a conductive resin, a metal or a copper plated metal, and mainly copper. The second insulating resin layer 109 and the third metal layer 110 are referred to as a second resin coated copper foil (RCC) layer.

Next, as shown in FIG. 4O, the third photoresist layer 111 is formed on the upper and lower portions of the double-sided substrate 101 on which the third metal layer 110 is formed.

Next, as shown in FIG. 4P, the third photoresist layer 111 is patterned 111a to pattern the third metal layer 110. In this case, the third photoresist layer 111 is a negative resist layer.

Next, as illustrated in FIG. 4Q, the third metal layer 110 is etched by irradiating light onto the patterned third photoresist layer 111a to expose the second insulating resin layer 109. Three metal pattern layers 110a are formed. Next, although not shown, the third photoresist layer 111a is removed. The second insulating resin layer 109 exposed by the third metal pattern layer 110a is a laser point for forming a laser via hole formed in a next process.

Next, as shown in FIG. 4R, the first insulation exposed by the second insulating resin layer 109 and the second metal pattern layer 107a exposed by the third metal pattern layer 110a. A single build-up laser (SBL) via hole is removed by removing the insulating resin layer 106 with a laser drill to expose a predetermined portion of the first metal pattern layer 103a. (Hereinafter, referred to as 'first laser via hole') 113a is formed. In addition, the second insulating resin layer 109 exposed by the third metal pattern layer 110a is removed by a laser drill so that a predetermined portion of the second metal pattern layer 107a is exposed. (Multi Build-up Laser: MBL) Via holes (hereinafter referred to as 'second laser via holes') 113b are formed. In this case, the laser drill is an etching apparatus for removing the insulating layer by irradiating a laser beam using a high-pressure carbon dioxide (Co ₂ ) gas.

Next, as shown in FIG. 4S, the fourth metal layer 114 is formed by performing panel plating on the upper and lower portions of the double-sided substrate 101 on which the first and second laser via holes 113a and 113b are formed. Form to a certain thickness.

Next, as shown in FIG. 4T, the filler 120 is filled to completely fill the first and second laser via holes 113a and 113b in which the fourth metal layer 114 is formed. In this case, the filler 120 may use any one of gold, silver, copper, a conductive resin, a metal plated with copper, a resin, or a conductive paste ink containing copper, and in this case, copper (Cu) ) Conductive paste ink is used.

The reason for containing the copper component in the metal component in the conductive paste ink is as follows.

First, copper is a good conductor of electricity and heat,

Secondly, it is flexible, good malleability, easy processing,

Third, because the chemical resistance is large and difficult to corrode.

Therefore, the conductive paste ink containing copper (Cu) (30-40%) is heat resistant (no deformation even at 288 ° C.), has a high conductivity when filling the laser via, and has a flatness of the laser via. This enables high bonding of BGAs or IC chips, high reliability of the product, and light and small shortening of the product. On the other hand, conventional conductive paste inks containing resin are weak in heat (deformation occurs at 288 ° C), weak in conductivity, weak in durability (impact resistance), and cause poor progression (weak in heat). Occurs.

The copper (Cu) component serves to improve plugging filling force due to the conductive paste ink component and copper (Cu) specific gravity (8.96).

The content of the fine copper (Cu) component that plays an important role in the conductive paste ink is shown in the following table.

ingredient Phenolic Novolac Polycidyl ether P-tert butyl phenyl ether Hardener of epoxy resin Defoamer Copper (Cu) component Composition ratio (wt%) 25-30 10 to 15 1 to 5 0.5 to 1 30-40

Then, the experimental results according to the change in the copper (Cu) content contained in the conductive paste ink will be described with reference to FIGS.

First, when the content of copper (Cu) contained in the conductive paste ink is 0 to 29% (first embodiment), 30 to 40% (second embodiment), and 41 to 100% It was carried out by dividing into (Example 3), and the printing conditions for printing the copper-containing conductive paste ink and the curing conditions for curing were carried out in the same manner.

At this time, the printing conditions of the copper-containing conductive paste ink was a semi-automatic printing machine working at a speed of 130mm / sec, and the drying conditions were the same curing using a conveyor dryer having six chambers . At this time, the first chamber of the conveyor drying, 150 ℃, the second chamber 165 ℃, the third to 6 chambers were cured step by step at 175 ℃.

First Embodiment (Conductive Paste Ink with a Copper Content of 0 to 29%)

7A and 7B are enlarged photographic cross-sectional views of a conductive paste ink having a copper content of 0 to 29% plugged into SBL and MBL laser via holes. FIG. 7A shows a state filled with an SBL laser via hole using a conductive paste ink having a copper content of 0 to 29%, and FIG. 7B shows a MBL laser using a conductive paste ink having a copper content of 0 to 29%. The via hole is filled.

7C to 7H are enlarged photographs and cross-sectional views for explaining the problems of SBL and MBL laser vias using a conductive paste ink having a copper content of 0 to 29%.

First, as illustrated in FIGS. 7C and 7D, an interlayer separation occurred at a plugging site during thermal stress (for example, three times for 10 seconds at a temperature of 288 ° C.).

7E and 7F, after the thermal shock, fine cracks were generated on the inner sidewall of the laser via hole.

In addition, as shown in FIGS. 7G and 7H, the lack of the copper component of the conductive paste ink lacks the fillability of the laser via hole and caused many surface depressions.

Second Embodiment (Conductive Paste Ink with a Copper Content of 30 to 40%)

8A and 8B are enlarged cross-sectional views of a conductive paste ink having a copper content of 30 to 40% by plugging printing into SBL and MBL laser via holes. FIG. 8A shows a state filled with an SBL laser via hole using a conductive paste ink having a copper content of 30 to 40%, and FIG. 8B shows a MBL laser using a conductive paste ink having a copper content of 30 to 40%. The via hole is filled.

8C to 8H are enlarged photographs and cross-sectional views for explaining the states of SBL and MBL laser vias using conductive paste inks having a copper content of 30 to 40%.

First, as illustrated in FIGS. 8C and 8D, no delamination occurred at the plugging site during thermal shock (for example, three times for 10 seconds at a temperature of 288 ° C.). And there was no lifting phenomenon in the upper part of copper plating.

8E and 8F, fine cracks did not occur on the inner sidewall of the laser via hole after the thermal shock. In addition, the lack of fillability and depression of the laser via hole caused by the lack of the copper component of the conductive paste ink did not occur.

In addition, as shown in Figure 8g and Figure 8h, the plugging filling properties of the laser via hole is also good, the abrasiveness at the time of belt sanding (Belt Sanding) due to the proper content of the copper component, and the flatness and copper plating properties are also good.

Third Embodiment (Conductive Paste Ink with a Copper Content of 41 to 100%)

9A and 9B are enlarged photographic cross-sectional views of a conductive paste ink having a copper content of 41 to 100% plugged into SBL and MBL laser via holes. FIG. 9A shows a state filled with an SBL laser via hole using a conductive paste ink having a copper content of 41 to 100%, and FIG. 9B shows a MBL laser using a conductive paste ink having a copper content of 41 to 100%. The via hole is filled.

9C to 9H are enlarged photographs and cross-sectional views for explaining the problems of SBL and MBL laser vias using a conductive paste ink having a copper content of 41 to 100%.

First, as shown in Figs. 9C and 9D, the internal composition and the coefficient of thermal expansion of the conductive paste ink due to the excessive content of the copper component during thermal stress (for example, three times for 10 seconds at a temperature of 288 ° C) Due to the difference in whitening, the whitening phenomenon occurred on the surface of the laser via hole. Then, the gold plating property deterioration phenomenon of the surface of the laser via hole occurred.

In addition, as shown in FIGS. 9E and 9F, the excessive content of the copper component caused a decrease in abrasiveness during belt sanding, thereby degrading flatness and copper plating property. FIG. 9E is a photograph showing sanding abrasive defects, and FIG. 9F is a photograph showing a state in which conductive paste ink remains due to abrasive polishing defects.

In addition, as shown in Figs. 9G and 9H, the excessive content of the copper component of the conductive paste ink lacks the fillability of the laser via hole and caused many surface depressions.

Next, the viscosity and particle size of the conductive paste ink are shown in the table below.

Viscosity (Pa.s / 25 ℃) Particle Size (μm) Pencil strength Heat resistance Curing conditions Copper Conductive Paste Ink (NC-735) 39 17.5 8 H No bubbles, cracks 150 ℃ × 60min

Herein, the copper particle size of the conductive paste ink is preferably 20 μm or less (≦ 20 μm).

Then, the experimental results according to the viscosity change in the conductive paste ink will be described with reference to FIG. 10.

First, experiments were conducted when the copper particle size of the conductive paste ink was 20 μm or less (≦ 20 μm) (first embodiment) and when 21 μm or more and 50 μm or less (21 μm ≤ particle size ≤ 50 μm) It divided into 2 Examples) and implemented.

Embodiment 1 (when copper particle size ≤ 20 µm of conductive paste ink)

FIG. 10A is a surface photograph when the copper particle size of the conductive paste ink is 20 μm or less (≦ 20 μm). FIG. As shown, the spreadability is good at the top plugging printing, the top cap open phenomenon is improved, and the plugging site printing state observation is good.

10B and 10C are enlarged cross-sectional views of SBL and MBL laser vias when the copper particle size of the conductive paste ink is 20 μm or less (≦ 20 μm).

Here, when the coating film height of the conductive paste ink is 60 μm, the coating film width of the ink is 480 to 500 μm, and the size of the copper particles in the ink is 20 μm, the SBL laser via (Fig. 10B) and the MBL laser via (Fig. Both ink filling and spreading properties of 10c) were good. And, no air pocket phenomenon occurred.

Second embodiment;

(When copper particle size of conductive paste ink is 21 micrometers or more and 50 micrometers or less)

FIG. 10D is a surface photograph when the particle size of the conductive paste ink is 21 µm or more and 50 µm or less (21 µm ≤ particle size ≤ 50 µm). As shown, the spreadability is weak during the upper end plugging printing, the cap open phenomenon due to the upper air pocket after the plugging printing frequently occurred, and the printing state of the plugging site was poor.

10E and 10F are enlarged cross-sectional views of SBL and MBL laser vias in which the conductive paste ink has a particle size of 21 μm or more and 50 μm or less (21 μm ≦ particle size ≦ 50 μm).

Here, when the coating film height of the conductive paste ink is 80 μm, the coating film width of the ink is 400 to 430 μm, and the size of the copper particles in the ink is 50 μm or more, the SBL laser via (FIG. 10E) is in a good state, but the MBL laser is good. Ink fillability of the vias (FIG. 10F) was markedly lacking. In addition, many air pockets have occurred.

Next, as shown in FIG. 4T, the filler 120 is filled with the inside of the first and second laser via holes 113a and 113b so as to be completely filled, and then a predetermined temperature (for example, 150 ° C.) is obtained. And the filler 120 is cured for a predetermined time (for example, 20 minutes or 30-40 minutes).

Next, as shown in FIG. 4U, the filler 120 protruding from the upper and lower portions of the double-sided substrate 101 is flattened by bending with a ceramic brush to expose the fourth metal layer 114. (Polishing twice). In this case, the filler 120a filled in the first and second laser via holes 113a and 113b is also referred to as a laser via.

Next, as illustrated in FIG. 4V, the fifth metal layer 121 is formed on the upper and lower portions of the double-sided substrate 101 on which the fourth metal layer 114 and the filler 120a are exposed to a predetermined thickness (eg, For example, 10 to 15 mu m). In this case, the fifth metal layer 121 may be formed of any one of gold, silver, copper, a conductive resin, a metal or resin plated with copper, and a copper paste having a copper content of 30 to 40%. do.

Next, as shown in FIG. 4W, a fourth photoresist layer 115 is formed on the fifth metal layer 121.

Next, as shown in FIG. 4x, the fourth photoresist layer 115 is patterned 115a. The fourth photoresist layer 115 is patterned by a mask (not shown) to form the solder resist layer 116 to be formed in a later process. In this case, the fourth photoresist layer 115 is a negative resist layer.

Next, as illustrated in FIG. 4Y, the fifth metal layer 115 and the fourth metal layer (eg, the fourth insulating layer 115a) are irradiated with light to expose the second insulating resin layer 109. 114, the third metal pattern layer 110a is sequentially etched.

Next, as shown in FIG. 4z, the fourth photoresist layer 115a is removed, and then a solder resist layer 116 is formed on the exposed second insulating resin layer 109 by screen printing.

5A and 5B are enlarged photographs showing a laser via hole photograph of a multilayered printed circuit board completed by the manufacturing process of the present invention and a partial region B of the photograph.

6 is a cross-sectional view of the laser via hole of the multilayer printed circuit board completed by the manufacturing process of the present invention.

As shown in the photographs of FIGS. 5A and 5B and the cross-sectional view of the laser via hole shown in FIG. 6, the ICs and the ball grid arrays (BGAs) are in electrical contact with these components when mounted. It can be seen that the contact area of the laser via hole of the printed circuit board is considerably wider than the conventional (FIG. 3) due to the fifth metal layer 121 formed on the laser via hole. Therefore, it is possible not only to improve contact and bonding characteristics when mounting electronic components on a printed circuit board, but also to increase conductivity and uniformity of an external metal pattern formed for power distribution, to reinforce entire via pads and to solder via pads. Advantages, such as improving a characteristic, can be obtained.

In addition, a process of forming a laser via by filling the first laser via hole 113a on which the fourth metal layer 114 is formed with the filler 120 is performed, followed by polishing the laser via 120a. Only by performing the process of making the upper and lower surfaces uniform, the contact area between the first laser via hole 113a and the electronic component mounted on the substrate can be increased, and the uniformity of the external metal pattern formed for power distribution can be achieved. It can increase. As a result, the solderability of the via pads can be improved, as well as the contact and bonding properties of the printed circuit board. In addition, it is possible to prevent the flow of the cream solder and to prevent the ink splashing during screen printing.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

As described above, in the method of manufacturing a multilayer printed circuit board according to the present invention, a laser via hole of a multilayer printed circuit board having a first conductor layer is filled with a filler of a conductor or resin type, and then a second conductor layer is formed thereon. By forming, it is possible to increase the contact area of the laser via hole, to improve the electrical contact and bonding characteristics with the electronic components mounted on the multilayer printed circuit board, and to improve the reinforcement characteristics and the soldering characteristics of the via pads. have.

In addition, the filler and the second conductor layer are separated at a high temperature by using the same material as that of the filler filled in the laser via hole of the multilayer printed circuit board on which the first conductor layer is formed and the second conductor layer formed thereon. The phenomenon can be prevented.

In addition, the ink filling in the laser via hole of the multilayer printed circuit board on which the first conductor layer is formed uses ink in which copper content of copper paste is 30 to 40%, thereby preventing deformation even at high temperature. It has no conductivity and is excellent in durability, and it is possible to reduce the thickness of the product.

In addition, it prevents the flow of cream solder due to the adjacent laser via hole and prevents ink splashing during screen printing when soldering to the via pad. It is possible not only to reduce the contact failure rate, but also to solve the problems caused in the process of mounting various electronic components by copper plating thereon, and to make the mounted electronic components function properly.

In addition, it is possible to solve a short problem when mounting a component due to the formation of a solder ball at the bottom of the integrated circuit (IC) and the ball grid array (BGA), and the integrated circuit (IC) and the ball grid array (BGA) The reliability of the printed circuit board can be improved by expanding the bonding area of the BGA.

In addition, the printed circuit board can be made light and thin, and the variety of design techniques can be pursued.

As a result, the laser via hole manufacturing method according to each embodiment of the present invention not only improves the manufacturing technology of a printed circuit board according to the rapidly changing electronic technology development, but also the ball grid array (BGA) and various fine electronic parts of the electronic parts. Since it can be accurately mounted and bonded, there is an advantage that can contribute to reducing even a small error.

Claims (14)

In the method of manufacturing a multilayer printed circuit board, Stacking a plurality of metal layers and insulating resin layers on a double-sided substrate on which buried via holes are formed to form a multi-layer substrate; Forming a plurality of laser via holes in the multilayer substrate; Forming a first metal layer over the structure; Filling the plurality of laser via holes in which the first metal layer is formed with conductive paste ink having a copper content of 30 to 40% and then planarizing the first metal layer to be exposed; Forming a second metal layer over the structure; And And partially patterning the first and second metal layers between the laser via hole and the laser via hole and the uppermost metal layer of the multilayer substrate to expose the uppermost insulating resin layer of the multilayer substrate, and then forming a solder resist layer. A method of manufacturing a multilayer printed circuit board characterized in that. The method of claim 1, Wherein the first metal layer comprises any one of gold, silver, copper, aluminum, a conductor, a conductive resin, a conductive paste ink containing copper, and a resin containing copper. The method of claim 2, The conductive paste ink is a conductive paste ink having a copper content of 30 to 40%. The method according to claim 1 or 3, The particle size of the copper contained in the conductive paste ink is 20㎛ or less manufacturing method of the printed circuit board. The method of claim 4, wherein The coating film height of the said conductive paste ink is 60 micrometers, The coating film width of the conductive paste ink is a manufacturing method of a multilayer printed circuit board, characterized in that 480 ~ 500㎛. The method of claim 1, And filling the laser via hole with the conductive paste ink and then curing the conductive via ink at a predetermined temperature and for a predetermined time before planarization. The method of claim 6, The curing process is a method of manufacturing a multilayer printed circuit board, characterized in that for 20 minutes at a temperature of 150 ℃. The method of claim 6, The curing process is dried using a conveyor dryer having first to sixth chambers, wherein the first chamber is 150 ° C, the second chamber is 165 ° C, and the third to sixth chambers are stepwise at 175 ° C. A method for manufacturing a multilayer printed circuit board, characterized in that hardening. The method of claim 1, And a ceramic brush is used to planarize the conductive paste ink. The method of claim 1, Wherein the second metal layer comprises any one of gold, silver, copper, aluminum, a conductive conductor, a conductive resin, a conductive paste ink containing copper, and a resin containing copper. The method of claim 10, The conductive paste ink is a conductive paste ink having a copper content of 30 to 40%. The method of claim 11, The particle size of the copper contained in the conductive paste ink is 20㎛ or less manufacturing method of the printed circuit board. The method of claim 1, wherein the multilayer printed circuit board is manufactured by: Forming a photoresist layer on the second metal layer; Forming a photoresist pattern layer using the photoresist layer using a mask pattern for forming the solder resist layer; And And etching the first and second metal layers and the top metal layer of the multi-layer substrate using the photoresist pattern layer as a barrier layer to expose the top insulating resin layer of the multi-layer substrate. Method of manufacturing a substrate. The method of claim 1, The soldering resist layer is a manufacturing method of a multilayer printed circuit board, characterized in that formed by a screen printing process.