KR102401424B1 - Cavity Printed Circuit Board Manufacturing Method Using Sand Blast - Google Patents

Abstract

The present invention provides a manufacturing method for uniformly manufacturing a cavity having a side length of 3 mm or less and a depth of 300 μm or more at a low production cost by applying a sandblasting method, and a printed circuit board including the cavity manufactured through the same.

Description

Cavity Printed Circuit Board Manufacturing Method Using Sand Blast

The present invention relates to a method for manufacturing a cavity printed circuit board using sand blasting and to a cavity printed circuit board manufactured by the manufacturing method. Through the present invention, it is possible to efficiently manufacture the cavity at once at a low production cost.

Recently, with the development of the electronic industry, the demand for high functionalization and miniaturization of electronic components is gradually increasing, and accordingly, the printed circuit board (PCB) field is also in increasing demand for miniaturization, thin film and multifunctionalization.

In order to meet these needs, various PCB structures or various methods are being developed. Representative examples include a coreless structure or an Embedded Trace Substrate (ETS) structure.

The built-in trace board structure is a structure in which active devices such as surface-mounted ICs or passive devices such as MLCC-type capacitors are mounted inside the printed circuit board.

In general, the built-in trace substrate structure includes applying an adhesive on a substrate on which a pattern is formed, placing an electronic device on the adhesive, separately preparing a prepreg having a cavity about the size of an electronic device, and then laminating it on the substrate on which the electronic device is disposed. method is manufactured.

Compared to the conventional PCB structure, the built-in trace board structure can secure a free space on the surface and increase the wiring density.

In addition, since the devices are connected in the vertical direction, the wiring length is greatly reduced, thereby reducing problems such as impedance generation and signal delay due to a parasitic effect in an electronic device using a high-frequency signal.

Although the embedded trace substrate structure has several advantages, it also has disadvantages that need to be addressed.

For example, the alignment of the cavity and electronic device is more difficult than the general alignment of other processes, and due to the difference in depth between the Plated Through Hole (PTH) and the Blind Via Hole (BVH), serious voids ( void) may occur, and voids may occur due to the density of the copper pattern and the fluidity of the adhesive when applying the adhesive. The generated void is a major cause of cracks in reliability evaluation.

In addition, it also has disadvantages such as occurrence of warpage, complex structural design, and increase in manufacturing cost due to complex processes.

Accordingly, research to implement a built-in trace substrate structure without a complicated process has recently been attracting attention.

A cavity printed circuit board (PCB) for implementing a built-in trace board structure is a board with a step difference in the part where components are mounted, and the overall thickness can be lowered even when thick components are mounted.

Recently, by inserting and assembling semiconductors or components into the cavity of the semiconductor package substrate, the final thickness of the substrate is thinned, the signal transmission speed is increased by reducing the circuit length, the heat dissipation effect is improved, and the circuit density must be increased. Printed circuit boards are being actively studied.

Conventionally, as a method of manufacturing a cavity printed circuit board, a mechanical routing method, a laser drill method, a fill-cut method, a prepreg window processing bonding method, and the like are known.

First, the mechanical routing method is a method of processing a cavity using a mechanical router, and the laser drilling method is a method of removing a space to be formed in a substrate by ablation with a laser.

In addition, the peel-cut method is a method of manufacturing a cavity by coating a release film such as polyimide tape, double-sided tape or release ink in the space where the cavity is to be formed in the substrate, then cutting it with a laser and peeling it off, The leg window processing bonding method is a method of attaching a prepreg punched in advance to the area where the cavity is to be formed.

Although each of these conventional methods of manufacturing a cavity printed circuit board has advantages, there are problems to be solved as follows in order to efficiently manufacture the cavity.

(1) Mechanical routing method: The thickness and depth control of the cavity must be very precise, and there is an inherent risk of mechanical damage to the floor circuit or other layers below.

(2) Laser drilling method: Depending on the size of the cavity to be manufactured, the laser processing time is long, the space depth of the cavity is limited, the productivity is low, and a circuit cannot be formed on the bottom surface.

(3) Peel-cut method: Precise positioning of the release film is required, repetitive automatic or manual labor is required, the thickness of the release film is limited, and slippage may occur during lamination, and the amount of cavity bottom during laser processing Damage to the tip may occur.

(4) Prepreg window processing bonding method: Dust generated during processing may cause defects in laminate molding, and it is difficult to apply to package substrates that require fine positioning due to material shrinkage/expansion, and bonding agent The resin fluidity of the prepreg must be maintained at all times.

In particular, in the case of the CO ₂ laser drilling method, which is most often used in the manufacture of cavity printed circuit boards, as the number of cavities increases in addition to the above-described technical limitations, expensive equipment expansion is also required, resulting in a very high production cost.

In order to solve the problems of the existing method for manufacturing a cavity printed circuit board as described above, a new method of manufacturing a cavity printed circuit board is required. In particular, there is a need for a cavity printed circuit board manufacturing method for manufacturing a deep uniform cavity, which is smaller in size than a conventional cavity, and has a low production cost.

1. Republic of Korea Patent No. 10-2092816 2. Republic of Korea Patent No. 10-1750836

Accordingly, in order to solve the above problems, an object of the present invention is to provide a method for manufacturing a cavity printed circuit board to which a sand blast method is applied. In particular, by applying the sandblasting method, a cavity with a uniform shape with a side length of 3 mm or less and a depth of 300 μm or more, which could not be manufactured by the conventional cavity printed circuit board manufacturing method, can be manufactured at a low production cost at once. .

According to an aspect of the present invention, a first step of performing a first sand blasting treatment on a printed circuit board at a first product advancing speed; and

Including;

A method for manufacturing a cavity printed circuit board is provided.

The injection pressure of the first sand blasting treatment or the second sand blasting treatment may be 4 kgf or more.

In addition, the first product advancing speed may be 20 mm/min or more.

In addition, the first step may be repeated three or more times, and the second step may be repeated two or more times.

Meanwhile, the depth of the cavity may be 250 μm or more, and the length of one side may be 4 mm or less.

According to another aspect of the present invention, there is provided a cavity printed circuit board manufactured by the method for manufacturing the cavity printed circuit board.

According to another aspect of the present invention, there is provided a cavity printed circuit board in which a cavity having a depth of 250 μm or more and a side length of 4 mm or less is formed.

According to another aspect of the present invention, there is provided an electronic component including the cavity printed circuit board.

According to these aspects, the problems of the prior art can be solved, and the present invention has a practical object to provide specific embodiments thereof.

As described above, the present invention provides a method for manufacturing a cavity printed circuit board by a sand blast method and a cavity printed circuit board manufactured thereby, and the manufacturing method can shorten the processing time and significantly reduce the process cost. can be reduced.

In addition, since the degree of freedom in designing the cavity is high, it is possible to greatly reduce the size of the component mounted in the cavity and make the final thickness of the printed circuit board very thin.

1 is a cross-sectional photograph of a substrate to which a sand blasting process of the present invention is applied.
2 is a graph showing changes in the size (length of one side) and depth of a cavity according to the injection pressure and product progress speed of sand blasting.
3 is a graph showing the change in the depth of the cavity according to the product progress speed when the injection pressure of the sand blasting treatment is 4 kgf.
Figure 4 is a photograph of the sand blasting equipment for the sand blasting process of the present invention.
5 is an optical micrograph of the cavity prepared in Examples and Comparative Examples of the present invention (in order from left to right, the length of one side of the cavity is 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm).
6 is an optical micrograph of a cavity cross section prepared according to Example 1 (FIG. 6A), Example 2 (FIG. 6B), and Example 3 (FIG. 6C) of the present invention.

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

Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Accordingly, since the configuration of the embodiments described in the present specification is only one of the most preferred embodiments of the present invention and does not represent all the technical spirit of the present invention, various equivalents and modifications that can be substituted for them at the time of the present application It should be understood that examples may exist.

In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the existence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that the existence or addition of numbers, steps, elements, or combinations thereof, is not precluded in advance.

Where various parameters are given herein as ranges, preferred ranges, or enumerations of upper preferred and lower preferred values, any pair of any upper range limit or preferred value and any lower range, regardless of whether ranges are separately disclosed. It is to be understood that all ranges formed of limits or preferred values are specifically disclosed.

When a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoint and all integers and fractions within the range. It is intended that the scope of the invention not be limited to the particular values recited when defining the ranges.

A method of manufacturing a cavity printed circuit board according to the present invention comprises: a first step of performing a first sand blasting treatment on the printed circuit board at a first product advancing speed; and

and a second step of additionally performing a second sandblasting treatment at a second product progress rate that is 1.5 times or more of the first product progress rate.

Preferably, the second product progress rate may be at least twice the first product progress rate.

A printed circuit board for sandblasting may be prepared by sequentially performing lamination, frontal, adhesion, exposure, development, baking, and etching processes.

First, in the lamination step, a prepreg layer (PP) and a copper film (CF) layer are sequentially laminated on both sides of a copper clad laminate (CCL), respectively.

The thickness and number of prepreg layers may be determined in consideration of the depth of the cavity formed through sand blasting.

For example, in order to form a cavity having a depth of 300 μm in a printed circuit board for sandblasting, the thickness of the prepreg laminated on one side of the CCL should be matched to the thickness of the cavity. The number of layers of prepreg that can have a thickness can be selected.

That is, a prepreg layer with a thickness of about 300 μm is used to form a cavity having a depth of 300 μm, a prepreg layer having a thickness of about 350 μm is used to form a cavity having a depth of 350 μm, and a cavity having a depth of 400 μm. A prepreg layer having a thickness of about 400 μm may be formed for the formation of , and a prepreg layer having a thickness of about 450 μm may be formed to form a cavity having a depth of 450 μm.

In addition, as shown in FIG. 1, the copper film layer determines the order of the layers in order from the top surface to the bottom surface. If there is a copper film layer, the order of the copper film layer can be determined from the first layer to the fourth layer in order from the copper film layer on the upper surface to the copper film layer on the lower surface.

For example, to form a cavity having a depth of 300 μm, a prepreg layer between a single-layer copper film layer and a two-layer copper film layer having a thickness of about 300 μm is used for the formation of a cavity having a depth of 350 μm. A prepreg layer between the 350 μm thick single copper film layer and the double copper film layer was placed between the 400 μm thick single copper film layer and the double copper film layer to form a cavity with a depth of 400 μm. For the prepreg layer, to form a cavity having a depth of 450 μm, a prepreg layer between a single copper film layer and a two-layer copper film layer having a thickness of about 450 μm may be formed.

On the other hand, after the cavity is formed, the thickness of the copper film layer of the second and third layers, which becomes the bottom layer of the cavity, may be 30 μm or more in order to withstand the sand blasting treatment.

After the lamination step, a front step of surface treatment for improving adhesion between the dry film and the copper film layer may be performed. The front step can be divided into a brush, which is a physical surface treatment for removing foreign substances, and a soft etching step using sulfuric acid, hydrogen peroxide, and the like.

Thereafter, an adhesion step of adhering the dry film and the copper film layer to the dry film may be performed using an adhesion roll in a state in which the temperature and pressure are adjusted.

After the adhesion step, an exposure step of curing the desired portion through light irradiation (eg, ultraviolet (UV) light irradiation) may be performed.

After the exposure step, a developing step of dissolving and removing the uncured portion by light irradiation with sodium carbonate (NaCO ₃ ) or the like is performed. After the developing step, a baking step may be additionally performed.

Thereafter, an etching step for removing the copper layer of the portion that is not cured and has been removed through the developing step may be performed.

On the other hand, the injection pressure of the first sand blast treatment or the second sand blast treatment may be 4 kgf or more, preferably 6 kgf or less.

The injection pressure can be adjusted according to the size and thickness of the cavity to be manufactured, but as shown in FIG. 2, when the injection pressure of the sand blasting treatment is less than 4 kgf, the cavity of the desired depth was not obtained, and the injection pressure of the sand blasting treatment was In the case of more than 6 kgf, a cavity of uniform depth could not be obtained. Cavity of uneven depth with uneven, wavy bottom of the cavity cannot be applied to actual products.

That is, when the injection pressure increases, the depth of the cavity can be increased, but the non-uniformity according to the depth of the cavity and the size of the cavity tends to increase, so the injection pressure must be adjusted within an appropriate range.

In addition, the first product advancing speed may be 20 mm/min or more, preferably 60 mm/min or less. As shown in FIG. 3, when the product progressing speed is less than 20 mm/min, the depth of the cavity increases, but a cavity with a uniform depth cannot be obtained. can't get

Therefore, in order to obtain a uniform cavity of a desired depth, it is necessary to combine the injection pressure and the product advance speed in an appropriate range, and it is preferable to perform the sand blasting process twice or more while changing the combination of the injection pressure and the product advance speed.

In particular, the first step may be repeated three or more times, and the second step may be repeated two or more times, and it is preferable that the second step has fewer treatments than the first step, and more preferably the second step It is preferable that the 1st step is 3 times or more and 5 times or less, and the 2nd step is 2 or more times and 3 times or less.

In addition, as the desired depth of the cavity increases, the number of times of processing in the first step and the second step may increase.

Although it depends on the depth of the cavity to be manufactured, if the number of treatments in the first step and the second step is less than the appropriate range, the cavity of the desired depth cannot be obtained, and the prepreg remains in a state that is not completely removed, When the number of times of treatment in the first step and the second step is more than the appropriate range, the dry film (DF) layer or the copper film layer is damaged.

On the other hand, the depth of the cavity manufactured by the manufacturing method is 200 μm or more, and the length of one side is 4 mm or less.

The depth of the cavity may be preferably 300 μm or more, 350 μm or more, 400 μm or more.

In addition, the size (length of one side) of the cavity may be preferably 3 mm or less, 2 mm or less, or 1 mm or less.

Meanwhile, as roughness of the bottom surface of the cavity, Ra may be 1 μm or less and Rz may be 1 μm or less.

The cavity printed circuit board in which the cavity is formed may be utilized for various electronic components.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

production example

A printed circuit board suitable for the depth of the cavity to be manufactured was prepared and sandblasted. As shown in FIG. 4, the nozzles of the sand blasting device are composed of 8 in 1 row and 7 in 2 rows having a diameter of 5 mm, the spacing between the nozzles is 35 mm, the nozzle height is 50 mm, and the spraying speed is 10 times/min (38 Hz). ) was.

In addition, as an abrasive, brown fused alumina was used. The abrasive includes Al ₂ O ₃ (93.31%), TiO ₂ (3.85%), SiO ₂ (1.26%) and Fe ₂ O ₃ (0.32%), and as a result of particle size measurement, d3 of the abrasive is 39.24 μm, d50 was 26.16 μm and d95 was 18.42 μm.

Examples and Comparative Examples

A cavity was prepared according to the preparation example, and according to the depth of the cavity to be manufactured, as shown in Table 1 below, the first sand blasting treatment (pressure: 4 kgf, speed: 30 mm/min) and the second sand blasting treatment (pressure : 4 kgf, speed: 60 mm/min) was adjusted.

Five cavities having different sizes were prepared under the conditions of each Example and Comparative Example, and the lengths of one side of the cavities were 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm.

cavity
depth
(μm) 1st sand blast 2nd sandblast result enter speed enter speed 4 kgf 30 mm/min 4 kgf 60 mm/min Example 1 300 3rd time Episode 2 Good Example 2 350 4 times 3rd time Good Example 3 400 5 times 3rd time Good Comparative Example 1 350 4 times Episode 2 PP remaining Comparative Example 2 350 5 times 1 time DF, copper foil breakage Comparative Example 3 400 5 times Episode 2 PP remaining Comparative Example 4 400 6 times 0 times DF, copper foil breakage

As shown in the optical microscope observation results shown in FIG. 5 , the depths were 300 μm, 350 μm, and 400 μm, respectively, and the length of one side was 1.0 mm in the first sand blasting treatment and the second sand blasting treatment conditions of Examples 1 to 3, respectively. , 1.5 mm, 2.0 mm, 2.5 mm and 3.0 mm cavities were formed in good condition.

It was confirmed that the prepreg (PP) remained or the dry film (DF) and the copper film layer (copper foil) were damaged in Comparative Examples 1 to 4 in which the number of treatments of the first sand blast treatment and the second sand blast treatment were changed. .

In particular, as a result of observing the cross section of the formed cavity with an optical microscope, a cavity with a length of 3 mm or less on one side and a depth of 300 μm or more was prepared in a good state under the conditions of Example 1 ( FIG. 6a ), conditions of Example 2 Under the conditions of Example 3, a cavity with a side length of 2 mm or less and a depth of 350 μm or more was prepared in good condition (FIG. 6b), and a cavity with a side length of 1 mm or less and a depth of 400 μm or more under the conditions of Example 3 was in good condition prepared (Fig. 6c).

That is, under the conditions of the sand blasting treatment of Examples 1 to 3, a cavity having a uniform shape having a depth of 300 μm or more and a side length of 3 mm or less could be manufactured.

Although described above with reference to the embodiments of the present invention, those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above content.

Claims (8)

A first step of performing a first sand blasting treatment on the printed circuit board at a first product advancing speed; and
a second step of additionally performing a second sand blasting treatment at a second product progress rate that is 1.5 times or more of the first product progress rate;
The injection pressure of the first sand blast treatment or the second sand blast treatment is 4 kgf or more,
The first product progress speed is 20 mm / min or more,
repeating the first step at least 3 times, and repeating the second step at least 2 times,
The depth of the formed cavity is 250 μm or more, and the length of one side is 4 mm or less,
The printed circuit board is made by laminating a Gripreg layer and a copper film layer,
The nozzle is composed of 8 in 1 row and 7 in 2 rows with a diameter of 5 mm, and a sand blasting device with an interval of 35 mm and a nozzle height of 50 mm is used.
Brown fused alumina containing Al ₂ O ₃ , TiO ₂ , SiO ₂ and Fe ₂ O ₃ , particle size d3 of 39.24 μm, d50 of 26.16 μm and d95 of 18.42 μm. ,
Method for manufacturing a cavity printed circuit board. delete delete delete delete delete delete delete

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