KR20060070216A - Method for fablicating ball grid array board having ballpad image for enhancing reliability - Google Patents

Abstract

The present invention increases the contact area between solder balls by increasing the connection area of solder ball pads, thereby increasing the connection strength when mounted on a wiring board, thereby suppressing crack generation of solder joints from impact or warpage, thereby improving connection reliability. It relates to a manufacturing method of a ball grid array substrate for securing the.

A method of manufacturing a printed circuit board according to the present invention may include forming at least one groove by processing a copper plating layer of a portion corresponding to a solder ball pad using depth control of a laser; Forming an outer layer circuit; Applying a solder resist to a portion where the outer layer circuit is formed; Opening the solder resist layer corresponding to a wire bonding pad and a solder ball pad; And performing surface treatment with gold plating on the portions formed by exposing and developing the solder resist.

Wire Bonding Pads, Solder Ball Pads, Solder Resist, Gold Plated Layers

Description

Method for manufacturing a ball grid array board having a ball pad shape for improving reliability {Method for fablicating ball grid array board having Ballpad image for enhancing reliability}

1A to 1G are cross-sectional views illustrating a flow of a conventional method for manufacturing a ball grid array substrate.

2A to 2H are cross-sectional views illustrating a flow of a manufacturing method according to a first embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

3A to 3H are cross-sectional views illustrating a flow of a manufacturing method according to a second embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

4A to 4H are cross-sectional views illustrating a flow of a manufacturing method according to a third embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

* Description of the symbols for the main parts of the drawings *

200: negative

201: insulating resin layer

202a, 202b: copper foil

203a, 203b: copper plating layer

204: home

205: Solder Resist

206a, 206b: gold plated layer

B: through hole

C: wire bonding pad

D: solder ball pad

The present invention relates to a method of manufacturing a ball grid array substrate, and more particularly, to increase the contact area between the solder ball by increasing the connection area of the solder ball pad to increase the connection strength when mounted on the wiring board The present invention relates to a method for manufacturing a ball grid array substrate for preventing cracks in solder joints from impact or warpage to secure connection reliability.

Recently, with the rapid spread of mobile information devices such as mobile phones, personal handy systems (PHS), note PCs, and VTRs (video tape recorders) with integrated cameras, various types of electric and electronic devices have increased demands for miniaturization, light weight, high performance, and high speed. Miniaturization of IC (LSI) is also required according to the house. As a result, it is changing into thin package, fine fit, and larger chip size and smaller pad pitch.

Therefore, the ball grid array and the chip sized package have greatly contributed to the miniaturization and high functionality of various electric and electronic devices. However, connection reliability is a problem after the ball grid array and the chip size package is mounted.

The ball grid array, chip size package is mounted on the wiring board by solder balls. This solder joint is very small, with a diameter of 0.2 to 0.5 mm, and its connection strength is weak. Therefore, the connection reliability such as dropping of the ball grid array, chip size package, cracking of the solder joint, and the like due to external stress such as impact or warpage is generated. Often not secured.

1A to 1G are cross-sectional views showing the flow of a conventional method for manufacturing a general ball grid array substrate.

As shown in FIG. 1A, a master plate 100, which is a copper clad laminate plate having copper foils 102a and 102b coated on both surfaces of the insulating resin layer 101, is prepared.

Next, as in 1b, a process of processing a mechanical through hole (A) for electrically connecting the upper and lower surfaces of the CCL (Copper Clad Laminate), which is an inner core material, is performed.

Further, as in 1c, the surface of the original plate 100 and the inside of the through hole A are copper plated 103a and 103b to be electrically conductive.

Next, as in 1d, outer layer circuits 103a and 103b are formed.

Thereafter, as in 1e, the solder resist 104 is applied to the portion where the outer layer circuits 103a and 103b are formed.

Next, as in 1f, a portion to be gold-plated is opened by exposing, developing, and drying the applied solder resist 104. The upper opening is referred to as a wire bonding pad 105 and the lower opening is referred to as a solder ball pad 106.

Finally, the surface treatment is performed on the wire bonding pad 105 and the solder ball pad 106 as in 1g.

The conventional method for manufacturing a ball grid array substrate described above has a problem in that solder balls fall well due to a small contact area and connection strength of a ball pad portion.

In addition, the conventional method of manufacturing the ball grid array substrate described above has a problem in that a solder joint is cracked due to impact or warpage when the solder ball is mounted on the wiring board because the connection area of the solder ball pad is small.

The technical problem of the present invention to solve the above problems is to increase the contact area between the solder ball pads by increasing the connection area of the solder ball pad to increase the connection strength when mounted on the wiring board to prevent cracking of the solder joint from impact or bending A method of manufacturing a ball grid array substrate for suppressing and securing connection reliability.

In order to solve the above technical problem, a method of manufacturing a printed circuit board according to the present invention comprises the steps of forming at least one groove by processing the copper plating layer of the portion corresponding to the solder ball pad using the depth control of the laser; Forming an outer layer circuit; Applying a solder resist to a portion where the outer layer circuit is formed; Opening the solder resist layer corresponding to a wire bonding pad and a solder ball pad; And performing surface treatment with gold plating on the portions formed by exposing and developing the solder resist.

Hereinafter, a method of manufacturing a ball grid array substrate having a ball pad shape for improving reliability according to the present invention will be described in detail with reference to the accompanying drawings.

2A to 2H are cross-sectional views illustrating a flow of a manufacturing method according to a first embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

As shown in FIG. 2A, a master plate 200, which is a copper clad laminate plate having copper foils 202a and 202b coated on both surfaces of the insulating resin layer 201, is prepared.

Here, there are various kinds of copper foil laminates such as glass / epoxy copper laminates, heat resistant resin copper laminates, paper / phenol copper laminates, high frequency copper laminates, flexible copper laminates (polyimide films), and composite copper laminates. In the manufacture of double-sided printed circuit boards and multilayer printed circuit boards, glass / epoxy copper clad laminates are mainly used.

In addition, although the disc 200 without inner layer was used, the disc of a multilayered structure, such as a 2-layer, a 4-layer, and a 6-layer, can also be used according to a use purpose or a use.

Next, as shown in Figure 2b, by forming a mechanical through hole (B) for electrically connecting the upper and lower surfaces of the inner core material CCL.

Here, when penetrating the through hole (B), the upper and lower portions of the disc must be penetrated so as to be perpendicular to the function of electrically connecting the wires. In addition, deburring removes burrs of copper foil and dust particles on the inner wall of the hole and dust, fingerprints, etc. on the surface of the copper foil generated during drilling. In addition, a lot of heat is generated during drilling to generate a smear that melts the resin and adheres to the inner wall of the hole, which plays a decisive role in degrading the quality of copper plating on the inner wall of the hole.

Next, as shown in FIG. 2C, copper plating layers 203a and 203b are formed on the surface of the original plate 200 and the inner wall of the through hole B to be electrically conductive by electroless plating and electrolytic plating.

Here, electroless copper plating is performed first, followed by electrolytic copper plating. The reason why electroless copper plating is performed before electrolytic copper plating is that electrolytic copper plating that requires electricity cannot be performed on the insulating layer. That is, in order to form the electroconductive film required for electrolytic copper plating, electroless copper plating is thinly performed as the pretreatment. Since electroless copper plating has a disadvantage in that it is difficult to process and economical, it is preferable to form the conductive portion by electrolytic copper plating.

As shown in FIG. 2D, at least one portion of the copper plating 203b layer of the portion corresponding to the solder ball pad at the bottom of the original plate 200 is processed using a laser by using a depth cintrol of the laser. To form a groove 204.

The depth of the groove 204 is preferably about 25 to 75% of the thickness of the copper plating layer 203b. Because, if the depth of the groove 204 is less than 25% of the thickness of the copper plating layer (203b), there is a problem that the effect of the present invention can not be seen. In addition, when the depth of the groove 204 exceeds 75% of the thickness of the copper plating layer 203b, it is processed to the insulating layer 201 out of a suitable manufacturing process range, there is a problem that the subsequent Ni / Au plating is not performed. Therefore, it is preferable that the depth of the groove 204 is about 25 to 75% of the thickness of the copper plating layer 203b.

In addition, the laser may use a YAG laser (Yttrium Aluminum Garnet laser), a carbon dioxide laser (CO ₂ laser) and the like. In addition, since the laser is heated and processed at a high speed, the heat deformation layer is narrow, and processing of a very hard material is easy. The non-contact type has the advantage of no wear and tear of the tool, and it is possible to finely process complex shaped parts, and there is no noise and vibration during operation.

In addition, when the laser beam is irradiated onto the surface of the object, the temperature of the material surface rises sharply, and near the surface is melted and evaporated, thereby removing the material and processing.

In addition, it is desirable to remove oxides and impurities generated due to heat generated during laser processing.

Next, as in 2e, outer layer circuits 203a and 203b are formed.

Here, the outer layer circuits 203a and 203b form an etching resist pattern on the liquid photosensitive material or the dry film using an artwork film or a glass mask. Subsequently, when the original plate 200 is immersed in the etching solution, the portion where the etching resist pattern is formed is not etched, so only copper foil of the portion remains and copper foil layers of other portions are removed to form the outer layer circuits 203a and 203b.

Further, when the etching resist is removed using the etching resist as a stripping solution, a printed circuit board on which the outer layer circuits 203a and 203b are formed is formed. The stripping solution is usually used NaOH or KOH. The outer layer circuits 203a and 203b are formed using this general semi additive process.

Thereafter, as shown in FIG. 2F, the solder resist 205 is applied to the portion where the circuits 203a and 203b are formed.

Here, solder resist means a film that covers the circuit pattern of a printed circuit board and prevents unwanted connection by soldering when the component is mounted, and provides insulation between the protection material and the circuit that protects the circuit pattern of the printed circuit board. It plays a role.

When the solder resist 205 is coated in the present invention, when fingerprints, oil, dust, etc. are deposited on the circuits 203a and 203b and the insulating layer 201, the solder resist layer 205 and the original plate 200 are in close contact with each other. A problem may arise.

Therefore, before applying the solder resist 205, it is preferable to perform a pretreatment to clean the substrate surface and impart a roughness to the substrate surface in order to improve the adhesion between the solder resist layer 205 and the original plate 200.

The method of applying the solder resist layer 205 may be a screen printing method, a roller coating method, a curtain coating method, a spray coating method, or the like.

In this case, the screen printing method is a method of directly printing a solder resist pattern, and the roller coating method is a method of coating a substrate by applying a thinner solder resist ink to a roller made of rubber than that used in the screen printing method.

In addition, the curtain coating method is a method using a lower viscosity solder resist ink than that used for roller coating, the spray coating method is a method of spray coating the resist ink.

Next, as in 2g, the upper and lower soldering resist layer 205 is closely adhered to the artwork film having a predetermined solder resist pattern printed thereon, and then exposed and developed so that the upper portion, which is the opening C, corresponding to the wire bonding pad. The lower solder resist layer 205, which is an opening D corresponding to the solder resist layer 205 and the solder ball pad, is opened using a laser. Here, it is preferable that the diameter of the opening part C and D of the soldering resist 205 is 350 micrometers.

In addition, since the laser is heated and processed at a high speed, the heat deformation layer is narrow and the processing of a very hard material is easy. The non-contact type has the advantage of no wear and tear of the tool, and it is possible to finely process complex shaped parts, and there is no noise and vibration during operation. When the laser beam is irradiated onto the surface of the object, the temperature of the surface of the material rises rapidly, the vicinity of the surface melts, and at the same time evaporates, the material is removed and processing is performed.

In addition, it is preferable to perform a process of removing the residue, foreign matter, etc. of the solder resist layer 205 remaining in the portion where the solder resist layer 205 of the master plate 200 is removed by using a plasma or the like.

Finally, as shown in FIG. 2H, the solder resist 205 is subjected to surface treatment with gold platings 206a and 206b on the portions formed through the exposure and development processes.

Here, the plate 200 is eroded in the gold plating working chamber and then electroplated using the DC rectifier to form the gold plating layers 206a and 206b. At this time, it is more preferable to use the method of calculating the area to be plated and applying gold to the DC rectifier to deposit gold.

In addition, in order to improve the adhesiveness with gold, it is preferable to first plate the nickel thinly, and then form the gold plating layers 206a and 206b.

3A to 3H are cross-sectional views illustrating a flow of a manufacturing method according to a second embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

As shown in FIG. 3A, an original plate 300, which is a copper clad laminate plate having copper foils 302a and 302b coated on both surfaces of the insulating resin layer 301, is prepared.

Next, as shown in Figure 3b, by forming a mechanical through hole (E) for electrically connecting the upper and lower surfaces of the inner core material CCL.

Next, as shown in FIG. 3C, copper plating layers 303a and 303b are formed on the surface of the disc 300 and the inner wall of the through hole E to conduct electrical conduction by electroless plating and electrolytic plating.

Next, as in 3d, outer layer circuits 303a and 303b are formed.

And, as shown in Figure 3e, by using a laser depth control (Depth cintrol) by processing a portion of the copper plating (303b) layer of the portion corresponding to the solder ball pad of the lower portion of the disc 300 by using a laser (laser) At least one groove 304 is formed.

The depth of the groove 304 is preferably about 25 to 75% of the thickness of the copper plating layer 303b. In addition, it is desirable to remove oxides and impurities generated due to heat generated during laser processing.

Thereafter, as shown in FIG. 3F, the solder resist 305 is applied to the portions where the circuits 303a and 203b are formed.

Next, as in 3g, the upper and lower soldering resist layer 305 is closely adhered to the artwork film on which the predetermined solder resist pattern is printed, and then exposed and developed to form an upper portion corresponding to the opening F on the wire bonding pad. The lower solder resist layer 305, which is an opening G corresponding to the solder resist layer 305 and the solder ball pad, is opened using a laser. Here, it is preferable that the diameters of the opening parts F and G of the soldering resist 305 are 350 micrometers. In addition, it is preferable to perform a process of removing the residue, foreign matter, etc. of the solder resist layer 305 remaining in the portion where the solder resist layer 305 of the master 300 is removed by using a plasma or the like.

Finally, as shown in FIG. 3H, the solder resist 305 is subjected to surface treatment with gold platings 306a and 306b on the portions formed through the exposure and development processes.

4A to 4H are cross-sectional views illustrating a flow of a manufacturing method according to a third embodiment of a ball grid array substrate having a ball pad shape for improving reliability according to the present invention.

As shown in FIG. 4A, a master plate 400, which is a copper clad laminate plate having copper foils 402a and 402b coated on both surfaces of the insulating resin layer 401, is prepared.

Next, as shown in Figure 4b, by forming a mechanical through hole (H) for electrically connecting the upper and lower surfaces of the inner core material CCL.

Next, as shown in FIG. 4C, copper plating layers 403a and 403b are formed on the surface of the disc 400 and the inner wall of the through hole H to be electrically conductive by electroless plating and electrolytic plating.

Then, as in 4d, outer layer circuits 403a and 403b are formed.

Thereafter, as shown in FIG. 4E, the solder resist 404 is applied to the portions where the circuits 403a and 403b are formed.

Next, as in 4f, the lower solder, which is the opening I corresponding to the solder ball pad, is exposed and developed by bringing the artwork film having a predetermined solder resist pattern printed on the lower solder resist layer 404 in close contact. The resist layer 404 is opened using a laser. Here, it is preferable that the diameter of the opening part I of the soldering resist 404 is 350 micrometers. In addition, it is preferable to perform a process of removing the residue, foreign matter, etc. of the solder resist layer 404 remaining in the portion where the solder resist layer 404 of the master 400 is removed by using plasma or the like.

And, as shown in Figure 4g, by using a laser depth control (Depth cintrol) by processing a portion of the copper plating (403b) layer of the portion corresponding to the solder ball pad of the lower portion of the disc 400 using a laser (laser) At least one groove 405 is formed.

The depth of the groove 405 is preferably about 25 to 75% of the thickness of the copper plating layer 403b. In addition, it is desirable to remove oxides and impurities generated due to heat generated during laser processing.

Next, as shown in FIG. 4H, the upper solder resist layer 404 is closely adhered to the artwork film having a predetermined solder resist pattern printed thereon, and then exposed and developed to form an upper solder that is an opening J corresponding to the solder ball pad. The resist layer 404 is opened using a laser. Here, it is preferable that the diameter of the opening part J of the soldering resist 404 is 350 micrometers. In addition, it is preferable to perform a process of removing the residue, foreign matter, etc. of the solder resist layer 404 remaining in the portion where the solder resist layer 404 of the master 400 is removed by using plasma or the like.

Here, the reason why the upper solder resist layer 404 is opened later is that when the lower solder resist layer 404 is opened, the wire bonding pad portion may be oxidized when the upper solder resist layer 404 is also opened. Therefore, it is preferable to open the upper solder resist layer 404 later.

Finally, as shown in FIG. 4I, the solder resist 404 is subjected to surface treatment with gold platings 406a and 406b on the portions formed through the exposure and development processes.

As described above, it can be seen that the three embodiments of the method of manufacturing the ball grid array substrate having the ball pad shape for improving the reliability have a difference in the order of forming the grooves in the copper plating layer.

Referring to Table 1, the difference between the conventional method and the ball grid array substrate according to the present invention is as follows.

Conventional method Example Ball One 1.3 Contact area One 1.5 Connection strength One 1.5 Design degree of freedom - Higher design freedom compared to NSMD.

As shown in Table 1, it can be seen that the method of manufacturing a ball grid array substrate having a ball pad shape for improving reliability according to the present invention compared to the conventional method is improved in all aspects such as ball content, contact area, and connection strength. have.

Although the present invention has been described above, this is only one embodiment, and it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. . However, it will be confirmed through the claims that such changes and modifications fall within the scope of the present invention.

As described above, the method of manufacturing a ball grid array substrate having a ball pad shape for improving reliability according to the present invention is mounted on a wiring board by solder balls, and then the connection strength of the solder connection portion is increased to increase the impact strength. There is an effect of securing the connection reliability by suppressing the occurrence of cracks from the outside such as bending.                     

In addition, the manufacturing method of the ball grid array substrate having a ball pad shape for improving the reliability according to the present invention is to increase the contact area between the solder ball pad and the solder ball of the ball grid array / chip size package substrate SMD ( When changing from solder mask defined (NSMD) to NSMD (Non solder mask defined) type, SMD can have the same amount of connection as NSMD type, thus increasing the degree of freedom of design.

Claims (7)

(A) processing the copper plating layer of the portion corresponding to the solder ball pad by using the depth control of the laser to form at least one groove; (B) forming an outer layer circuit; (C) applying a solder resist to the portion where the outer layer circuit is formed; (D) opening the solder resist layer corresponding to a wire bonding pad and a solder ball pad; And (E) a method of manufacturing a ball grid array substrate, comprising the step of performing a surface treatment with gold plating on a portion formed through the exposure and development process of the solder resist. (A) forming an outer layer circuit; (B) processing the copper plating layer of the portion corresponding to the solder ball pad by using the depth control of the laser to form at least one groove; (C) applying a solder resist to the portion where the outer layer circuit is formed; (D) opening the solder resist layer corresponding to a wire bonding pad and a solder ball pad; And (E) a method of manufacturing a ball grid array substrate, comprising the step of performing a surface treatment with gold plating on a portion formed through the exposure and development process of the solder resist. (A) forming an outer layer circuit; (B) applying a solder resist to the portion where the outer layer circuit is formed; (C) opening the solder resist layer corresponding to a wire bonding pad and a solder ball pad; (D) processing the copper plating layer of the portion corresponding to the solder ball pad by using the depth control of the laser to form at least one groove; And (E) a method of manufacturing a ball grid array substrate, comprising the step of performing a surface treatment with gold plating on a portion formed through the exposure and development process of the solder resist. The method of claim 1, After the step of forming at least one groove by processing the copper plating layer of the portion corresponding to the solder ball pad using the depth control of the laser, (F) A method of manufacturing a ball grid array substrate, characterized in that it removes oxides and impurities generated due to heat generated during laser processing. The method of claim 1, After opening the solder resist layer corresponding to the wire bonding pad and the solder ball pad, (F) A method of manufacturing a ball grid array substrate, comprising performing a step of removing residues, foreign matters, and the like, of a solder resist layer remaining in a portion where a solder resist layer of a master is removed. The method according to any one of claims 1 to 3, And the groove has a depth of at least one groove of 25 to 75% of a thickness of the copper plating layer. The said open solder resist layer is 350 micrometers in diameter, The manufacturing method of the ball grid array substrate in any one of Claims 1-3 characterized by the above-mentioned.

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