KR101530265B1 - Method for manufacturing printed circuit board using PSR - Google Patents

Abstract

It is an object of the present invention to provide a method of manufacturing a printed circuit board in which the curing time of the PSR is shortened. In order to achieve the above object, the present invention provides a method of manufacturing a printed circuit board for printing a PSR on a substrate, wherein the PSR is pre-cured and / or post-cured using an electron beam.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a printed circuit board using a PSR,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly, to a method of manufacturing a printed circuit board using PSR (Photo Solder Resist or Photo Imageable Solder Resist).

PSR is often used when manufacturing printed circuit boards, especially BOC (Board On Chip) packages. The purpose of PSR is to prevent short between patterns and to support solder ball. The lead frame type PSR is a solder paste, and when the lead frame is attached to a substrate, it serves as an insulation for preventing a short circuit between patterns. The BGA (Ball Grid Array) type PSR is a solder paste solder balls to be attached to the substrate in place and to prevent shorting by ball and solder paste adjacent to each other during reflow.

BOC (Board on Chip) package is manufactured as a pre-cure. First, the PSR is printed on the ball attach surface of the substrate and then pre-cured. The temperature is gradually increased from room temperature (23 ° C) to 75 ° C, and then gradually cooled . Subsequently, PSR is printed on the chip attach side of the substrate, and then precure is performed. In this case, the substrate is heated from room temperature (23 ° C) to 80 ° C, and then slowly cooled. After the precured product is exposed and peeled, a post-cure is performed. The time required for precure here is about 160 minutes, and the time required for post cure takes about 215 minutes.

Thus, conventionally, since the PSR printed on the printed circuit board is hardened by the heat curing method, the curing time is long.

It is an object of the present invention to provide a method of manufacturing a printed circuit board in which the curing time of the PSR is shortened.

According to an aspect of the present invention,

There is provided a method of manufacturing a printed circuit board on which a PSR is printed on a substrate, wherein the PSR is pre-cured using an electron beam.

In order to achieve the above object,

There is provided a method of manufacturing a printed circuit board in which a PSR is printed on a substrate and then the PSR is pre-cured, wherein the PSR is post-cured using an electron beam.

According to the present invention, an electron beam is used to precure and post-cure a PSR printed on a substrate.

Accordingly, the pre-cure and post-cure time are greatly shortened, and the production cost is reduced, and the production time is shortened.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

FIG. 1 is a flowchart sequentially illustrating a method of manufacturing a printed circuit board according to the present invention, and FIGS. 2 to 7 sequentially illustrate a manufacturing process of a printed circuit board according to the present invention. The method of manufacturing the printed circuit board shown in FIG. 1 will be described in detail with reference to FIGS. 2 to 7. FIG.

Referring to FIG. 1, a method of manufacturing a printed circuit board includes first through seventh steps 111 through 171.

In the first step 111, surface treatment of the substrate (201 in Fig. 2) is performed. Referring to FIG. 2, a circuit pattern, for example, a ball pattern 205, on which solder balls are to be formed, is formed on the substrate 201 before the surface treatment of the substrate 201 is performed. In order to form the ball pattern 205, a conductive layer such as copper is formed on the substrate 201, a photoresist is coated on the conductive layer, and then masking, exposure and development development) process sequentially. Since this process corresponds to a conventional method, a detailed description thereof will be omitted.

The ball pattern 205 is subjected to surface treatment. That is, the surface of the ball pattern 205 is removed by a predetermined thickness, for example, 5 to 10 [um] using an etchant, and then the surface is treated using an OSP (Organic Solderability Preservative) method to form a plating layer 211. In the OSP method, an OSP resist, for example, OSP chemical or OSP organic material is applied instead of the plating layer 211 on the surface of the ball pattern 205 to prevent air from contacting the surface of the ball pattern 205, Thereby preventing oxidation of the pattern 205. The OSP resist applied to the surface of the ball pattern 205 is also referred to as a pre-flux treatment since it is a material substantially similar to a flux. When the OSP resist is applied to the surface of the ball pattern 205 in the OSP system, the ball pattern 205 is oxidized when the resist is not uniformly applied to the surface of the ball pattern 205, It is preferable to proceed immediately to the next step after the surface treatment.

3, a first PSR (Photo Solder Resist or Photo Imageable Solder Resist) is printed on the entire surface of the substrate 201 (see FIG. 3) as a second step 121. Referring to FIG. 3, The first PSR 221 is printed on the first PSR 221. The first PSR 221 is in the form of a gel, that is, a non-irregular paper. .

In the third step 131, the first PSR (221 in FIG. 4) is pre-cured using the electron beam (421 in FIG. 4). Referring to FIG. 4, an electron beam apparatus 401 isolated from a substrate 201 is aligned on a substrate 201 so as to be perpendicular to the substrate 201. The electron beam apparatus 401 is equipped with a plurality of micro-tips 411, and an electron beam 421 is emitted from the plurality of micro-tips 411. The electron beam 421 emitted from the electron beam apparatus 401 passes through the substrate 201 and the first PSR 221 formed on the substrate 201 is semi-cured. That is, the first PSR 221 does not melt as a partially crosslinked state, but swells in the solvent to become a state in which it is not dissolved. That is, it corresponds to the state of the resin in the phenol resin.

In the fourth step 141, the second PSR (231 in Fig. 5) is printed on the entire surface of the substrate (201 in Fig. 5). Referring to FIG. 5, the second PSR 231 is printed on the semi-cured first PSR (221 in FIG. 4).

In the fifth step 151, the first and second PSRs (221 and 231 in Fig. 6) are precured using the electron beam (421 in Fig. 6). 6, the electron beam apparatus 401 isolated from the substrate 201 is aligned on the upper side of the substrate 201 so as to be perpendicular to the substrate 201, and then the electron beam apparatus 401 is operated to move the electron beam apparatus 401, So that the electron beam 421 is emitted. As the electron beam 421 passes through the substrate 201, the second PSR 231 formed on the substrate 201 is semi-cured, and the first PSR 221 is completely cured to become a completely crosslinked state. That is, the first PSR 221 becomes a resin having an insoluble and infusible three-dimensional structure. This corresponds to the state of the resin in the phenolic resin.

As described above, when precure is performed using the electron beam (421 in FIG. 4 and FIG. 6), the time is shortened by three times or more as compared with the conventional thermal curing method. For example, when the conventional thermal curing method is used, the precure time takes 160 minutes, whereas when the electron beam (421 of FIGS. 4 and 6) is used according to the present invention, the precure time takes less than 50 minutes.

As described above, according to the present invention, the PSR (221 and 231 in FIG. 6) is precured by using the electron beam (421 in FIG. 4 and FIG. 6), thereby greatly shortening the process progress time.

In the sixth step 161, holes (611 in FIG. 7) are formed on the ball pattern (205 in FIG. 7) by patterning the first and second PSRs (221 and 231 in FIG. 6). Referring to FIG. 7, the second PSR 231 is patterned by masking, exposing and developing the printed substrate 201. Therefore, holes 611 are formed on the ball pattern 205. Thereafter, solder balls for electrically connecting the substrate 201 to the external device through the semiconductor packaging process are formed in the holes 611.

The first and second PSRs (221 and 231 in Fig. 6) each require a base, a thermosetting agent and an initiator. The mixing ratio of the base and the thermosetting agent is 7: 3. For example, a mixture of 0.7 [kg] of a subject and 0.3 [kg] of a thermosetting agent is used. As the initiator, a cationic initiator and a radical initiator may be used. Initiator mixing standards use an initiator that weighs from a few grams to a few tens of grams when the subject of the PSR is 0.7 [kg].

The configuration of the PSR can be configured as follows.

1. Topic

2. Topic + Thermal curing agent

3. Topic + Thermal curing agent + Initiator

An electron beam source (E-beam source) provided in the electron beam apparatus (401 in FIG. 4 and FIG. 6) uses a beta ray. The depth of penetration of the electron beam (421 in FIGS. 4 and 6) increases in proportion to the amount of energy. For example, 100 [keV] is proportional to 1 [mm] and 200 [keV] is proportional to penetration depth of 10 [mm]. At this time, the irradiation energy of the electron beam (421 in FIG. 4 and FIG. 6) is irradiated in an air or nitrogen atmosphere using an electron accelerator having a voltage of 50 [eV] to 1 [MeV]. In the case of precure, it is investigated in the range of 1 ~ 5 [kGy]. And electron beams (421 in FIG. 4 and FIG. 6) are irradiated at a post-cure time of 60 to 100 [kGy]. At this time, the current is 0.5 to 20 [mA].

After the electron beam (421 in FIG. 4 and FIG. 6) is irradiated to the substrate (201 in FIG. 1 to FIG. 7) in a dosage of 1 to 5 [kGy], ultraviolet exposure is performed using a mask . The PSR development is checked by measuring the open diameter of the hole (611 in FIG. 7) by developing the substrate (201 in FIGS. 1 to 7) exposed to ultraviolet rays. Table 1 below shows the results of the PSR pre-cure test using the electron beams (421 in FIG. 4 and FIG. 6).

division A1 A2 A3
PSR
subject O O O Heat curing agent X O O Initiator X X O Electron beam [kGy] 1-3 5 1-3 UV-rays 400 700 400/700 Average of hole diameter 0.412 0.413 0.415

In Table 1, O means inclusion and X means no inclusion. In addition, A1, A2, and A3 coincide with A1, A2, and A3 shown in FIG.

9 is for comparing the state of the hole diameter according to the configuration of the PSR. In FIG. 9, A1 is a case where the PSR is composed of only a subject, A2 is a case where the PSR is composed of a subject and a heat curing agent, and A3 shows a case where the PSR is composed of a subject and a heat curing agent and an initiator.

7 and 6, the spec of the diameter (611 in FIG. 7) is 0.400 mm-0.024 mm. Referring to FIG. 9 and Table 1, 611) It can be seen that the average value of the diameters is all within the specified specification range.

The diameter of the hole (611 in FIG. 7) varies depending on the intensity of the ultraviolet rays upon ultraviolet exposure.

In a seventh step 171, a post-cure process using an electron beam (421 in FIG. 8) is performed. 8, an electron beam apparatus 401 is aligned on a substrate 201 in a state where a plurality of holes 611 are formed on a ball pattern 205. An electron beam 421 is emitted from an electron beam apparatus 401, The first and second PSRs 221 and 231 formed on the substrate 201 are cured. At this time, the electron beam post cure can be performed at a rate of 4 [m / min] on the basis of one pass. Accordingly, post cure can be completed in approximately 28 minutes when the 110 [M] BOC (Board On Chip) product is used as a reference.

As described above, by advancing the post cure using the electron beam (421 in Fig. 8), the curing time is significantly shortened as compared with the conventional thermal curing method. That is, it takes about 215 minutes to carry out the post cure by the conventional thermal curing method. However, according to the present invention, only 28 minutes are required to carry out the post cure using the electron beam (421 of FIG. 8) The curing time can be shortened by about 7 times.

In addition, when the electron beam (421 in FIG. 8) is used, the ultraviolet cure does not need to be performed separately because the PSR (221, 231 in FIG. 8) can be completely cured. Therefore, the process is shortened and the process time is shortened.

10 is a graph for comparing the results of executing Post Cure using an electron beam according to the present invention and the results of executing Post Cure using a conventional thermal curing method, admit. In Fig. 10, B1 is a result of Post Cure using a conventional thermal curing method, and B2-B5 is a result of Post Cure using an electron beam of the present invention. In this case, B1 is the case when the PSR contains the subject and the heat curing agent, B2 is the subject only to the PSR, B3 is the subject and the cation initiator to the PSR, B4 is the subject and the heat curing agent to the PSR, A curing agent and a cationic initiator.

As shown in Fig. 10, when the post cure is performed using the conventional thermal curing method and the post cure is performed using the electron beam (421 in Fig. 8) according to the present invention, the diameter of the hole (611 in Fig. 8) And the PSR (221 and 231 in FIG. 8) of the surface of the PSR (221 and 231 in FIG. 8) and the lead heat resistance of the PSR. That is, even if the post cure is performed using the electron beam (421 in FIG. 8), the effect is almost the same as that using the conventional thermal curing method, but the curing time is significantly shortened compared with the conventional case.

Although the present invention has been described with reference to the embodiments shown in the drawings, it is to be understood that various modifications and equivalent embodiments may be made by those skilled in the art without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1 is a flowchart sequentially illustrating a method of manufacturing a printed circuit board according to the present invention.

FIGS. 2 to 7 are views sequentially illustrating the manufacturing process of the printed circuit board according to the present invention.

Description of the Related Art

201: substrate, 205: ball pattern

211: plating layer, 221/231: first and second PSR

401; Electron beam device, 411; Microtips

421; Electron beam, 611; Holes

Claims (9)

A method of manufacturing a printed circuit board (PSR) for printing a PSR on a substrate, Printing a first PSR on the substrate; A first precure step of precuring the first PSR using an electron beam to semi-cure the first PSR; Printing a second PSR over the first PSR in a semi-cured state on the substrate; A second precure step of completely curing the first PSR using the electron beam and of semi-curing the second PSR; And Masking, exposing, and developing the first PSR and the second PSR simultaneously after the second precure step. delete delete delete delete delete delete delete delete

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