JP2014107560A - Resist and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the bonding force to a solder ball by forming resist gradually, and differentiating the diameter of apertures formed in the resist layer at respective stages.SOLUTION: A resist 100 covering a pad layer formed on the outer layer of a substrate, and having a via hole 100a so as to partially expose the upper surface of the pad layer is configured so that resist layers 110, 120, each having an aperture 110a formed therein, are laminated in multilayer. The aperture 110a formed in each resist layer has a diameter smaller than that of the aperture of a resist layer laminated on the upper surface of each resist layer 110, 120. A production method of resist is also provided.

Description

  The present invention relates to a resist and a manufacturing method thereof, and more specifically, an opening that covers a pad layer formed on an outer layer of a substrate and exposes a part of the upper surface of the pad layer for bonding a solder ball. The present invention relates to a formed resist and a manufacturing method thereof.

  A printed circuit board (PCB) is a board in which a circuit line (line pattern) is printed and formed on a conductive material such as copper on an electrically insulating board, and the board just before mounting an electronic component. is there. In other words, in order to mount many types of electronic components on a flat plate, the mounting position of each component is determined, and the circuit board that connects the electronic components is printed and fixed on the surface of the flat plate. means.

  Various methods are used to mount electronic components, such as semiconductor chips, on such a printed circuit board (PCB), but recently, it has responded to higher density of semiconductor chips and higher signal transmission speeds. As a technique for achieving this, there is an increasing demand for a technique for directly mounting a semiconductor chip on a printed circuit board instead of CSP (Chip-Sized Package) mounting or wire bonding mounting.

  As described above, in order to directly mount the semiconductor chip on the printed circuit board, it is necessary to develop a high-density and high-reliability printed circuit board that can cope with the higher density of the semiconductor. Accordingly, a flip chip bonding method has attracted attention.

  The flip chip bonding method is a technique in which an individual semiconductor chip is not directly packaged but bonded to a printed circuit board as it is, and is inserted between the semiconductor chip and the printed circuit board. A BGA (Ball Grid Array) method using a solder ball as an output terminal is actively used.

  Such a flip chip bonding method not only has excellent electrical characteristics because the connection distance between the semiconductor chip and the connection pad is very short, but also because the back side of the semiconductor chip is exposed to the outside. The thermal characteristics are also excellent, and there is an advantage that bonding is easy due to the self-alignment characteristics of the solder balls.

  More specifically, the solder ball bonding structure includes a pad layer formed on the outer layer of the printed circuit board and a resist formed with a via hole that covers the pad layer and exposes a part of the upper surface of the pad layer. A solder ball is mounted on the pad layer exposed through the opening.

  On the other hand, in order to increase the density of circuits, the distance between circuits including the pad layer is 100 μm or less, more narrowly 50 μm or less, and the circuit width is further miniaturized to 20 μm or less.

  Under such circumstances, the diameter of the via hole in which the solder ball is mounted is also reduced. As the via hole diameter decreases, the density of the circuit increases, but the cross-sectional area between the pad layer and the semiconductor chip decreases and mechanical stress increases rapidly, thereby causing cracks at the connection site. May occur.

  In addition, due to weakened adhesive strength, it is easy to peel off even with a slight impact applied to the solder ball. When the solder ball is bonded by the BGA method, any one of the bonded portions of the plurality of solder balls provided is peeled off. As a result, the entire chip cannot be used. As a result, development of a technique for improving the durability by increasing the adhesive force between the pad layer and the solder ball is continuously demanded.

  In relation to this, Korean Published Patent Application No. 10-2007-0118846 (hereinafter referred to as Prior Art Document 1) discloses that a blind via hole is formed at a position where a solder ball is formed to expose the solder ball land, A structure is disclosed in which lands for assisting adhesion of solder balls are formed on the solder resist on the upper ends of both sides of the blind via hole.

  However, the above prior art documents only add a bonding land with a solder ball to strengthen the bonding force with the solder ball, and the conventional via hole form in which the solder ball is mounted and its manufacture are conventional. Since this technique is used as it is, it is not a more fundamental alternative for securing the bonding force with the solder ball.

  In addition, since another structure called a solder ball bonding auxiliary land has to be additionally inserted, the thickness of the substrate increases from the existing one, which complicates the process, leading to a decrease in productivity and an increase in process cost. There's a problem.

Korean Published Patent No. 10-2007-0118846

  The present invention is for solving the above-mentioned problem, and forms a resist stepwise, and the diameter of the opening formed in the resist layer at each step is made different. The purpose of this is to increase the bonding strength.

  According to the present invention made to achieve the above object, a resist is provided that covers a pad layer formed on the outer layer of the substrate and has a via hole formed so that a part of the upper surface of the pad layer is exposed. The resist is configured in a form in which a plurality of resist layers in which openings are formed are laminated, and the openings formed in the resist layers are resist layers laminated on the upper surfaces of the resist layers. A resist is provided having a diameter smaller than the opening.

  In addition, a resist is provided in which the opening formed in each resist layer has its center located on the same vertical line.

  In addition, a resist is provided in which the diameter of the opening formed in each resist layer is 60 to 80% of the diameter of the opening formed in the resist layer on the upper surface of each resist layer.

  In addition, a resist having a form in which the side wall of the opening formed in each resist layer is inclined is provided.

  Further, each resist layer is provided with a resist in which a resist in a liquid state is cured or a resist film in a dry state.

  According to another embodiment of the present invention made to achieve the above object, a via hole is formed so as to cover the pad layer formed on the outer layer of the substrate and to expose a part of the upper surface of the pad layer. The resist is bonded to a first resist layer in which an opening having a constant diameter d1 is formed to expose a part of the upper surface of the pad layer, and an upper surface of the first resist layer; And a second resist layer having an opening having a diameter d2 larger than the diameter d1.

  In addition, the openings formed in the first and second resist layers have their centers located on the same vertical line, and the diameter of the opening formed in the first resist layer is the same as that of the second resist layer. A resist is provided that is 60-80% of the diameter of the formed opening.

  According to the present invention made to achieve the above object, (a) a step of forming a first resist layer on the substrate having a pad layer formed on the outer layer, and (b) a predetermined position of the first resist layer. (C) forming a second resist layer on the first resist layer; and (d) a diameter of the opening formed in the first resist layer. and processing an opening having a diameter d2 larger than d1 at a predetermined position of the second resist layer.

  The first or second resist layer may be formed by applying a liquid resist on the top of the substrate by a squeezing method and then curing the resist. Is done.

  The first or second resist layer may be formed by bonding a dry resist film to an upper portion of the substrate.

  The opening is formed by selectively exposing and developing the first resist layer or the second resist layer after bringing a mask close to the top of the first resist layer or the second resist layer. A method for producing a resist is provided.

  Further, there is provided a resist manufacturing method in which the opening is formed by laser processing.

  According to the present invention, the via hole in which the solder ball is mounted has a shape in which both side walls have a stepped shape and the diameter decreases toward the lower portion. By having it, the bonding strength between the substrate and the solder ball is further enhanced.

  In addition, the adhesion of the resist layers can be further improved by forming the resist of the present invention by stepwise lamination of resist layers and forming the resist layer by a squeezing method.

  In addition, since the opening is processed for each of the resist layers to be laminated, the thickness of the resist layer to be removed can be adjusted. Defects such as a cut (Under Cut) can be prevented, and a via hole having a more accurate shape can be formed.

It is sectional drawing of the resist by this invention. It is sectional drawing of the resist by other embodiment of this invention. It is process drawing which illustrated the manufacturing method of the resist of this invention in order. It is process drawing which illustrated the manufacturing method of the resist of this invention in order. It is process drawing which illustrated the manufacturing method of the resist of this invention in order. It is process drawing which illustrated the manufacturing method of the resist of this invention in order.

Advantages and features of the present invention and methods for accomplishing them will become apparent with reference to the embodiments described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The embodiments can be provided to complete the disclosure of the present invention and to fully convey the scope of the invention to those who have ordinary knowledge in the technical field to which the present invention belongs. Like reference numerals refer to like elements throughout the specification.

  The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, the singular forms also include the plural forms unless specifically stated otherwise. As used herein, “comprise” and / or “comprising” refers to a component, stage, operation and / or element referred to is one or more other components, stages, operations and Do not exclude the presence or addition of elements.

  Referring to FIG. 1, a resist 100 according to the present invention has a via hole 100 a that covers a pad layer 11 formed on an outer layer of a substrate 10 and exposes a part of the upper surface of the pad layer 11.

  In order to clearly explain the main features of the invention, FIG. 1 illustrates the structure of the substrate 10 in a simplified manner. The substrate 10 includes circuit wiring therein, and is formed on one surface of an insulating layer. Only a single-sided substrate 10 on which circuit wiring is formed, a double-sided substrate 10 on which circuit wiring is formed on both sides, and a multilayer substrate 10 on which multilayer circuit wiring is formed are used as various types of substrates 10. Of course you can. Although not shown in the drawing, in addition to the pad layer 11, outer layer circuit wiring can be formed on the outer layer of the substrate 10.

  The resist of the present invention is formed in a form in which a plurality of resist layers are laminated, each resist layer has an opening having a constant diameter, and a part of the upper surface of the pad layer 11 is exposed to the outside. Let

  Specifically, the opening formed in each resist layer has a smaller diameter than the opening of the resist layer laminated on the upper surface of each resist layer.

  For example, as shown in FIG. 1, the resist 100 includes two resist layers, that is, a first resist layer 110 and a second resist layer 120 stacked on the first resist layer 110. As a result, the opening 110 a formed in the first resist layer 110 has a smaller diameter than the opening 120 a formed in the second resist layer 120.

  Similarly, assuming that the resist 100 is composed of three resist layers, the opening formed in the lowermost resist layer has the smallest diameter, and the resist layer thereon has a larger diameter. The opening formed in the uppermost resist layer has the largest diameter.

  At this time, the centers of the openings 110a and 120a are located on the same vertical line. Accordingly, the via hole 100a of the present invention formed by the openings 110a and 120a has a shape in which both side walls have a stepped shape and a diameter decreases toward the lower part. As a result, when the spherical solder ball is mounted through the via hole 100a, the resist 100 of the present invention has a lower part of the spherical solder ball and more bonding surfaces. The bonding strength of is strengthened.

  Here, the diameters of the openings 110a and 120a formed in the resist layers 110 and 120 are 60 to 80% of the diameters of the openings formed in the resist layer on the upper surface of the resist layers 110 and 120, respectively. It is preferable.

  For example, the diameter d1 of the opening 110a formed in the first resist layer 110 may be 60 to 80% of the diameter d2 of the opening 120a formed in the second resist layer 120. If the resist 100 is composed of three resist layers, the diameter of the opening formed in the lowermost resist layer is equal to the diameter of the opening formed in the middle resist layer. It is 60 to 80%, and the diameter of the opening formed in the middle resist layer can be 60 to 80% of the diameter of the opening formed in the uppermost resist layer.

  If the diameter of the opening formed in the lower resist layer is too small or too large compared to the upper resist layer, the side wall of the via hole 100a becomes close to a right-angled shape. Therefore, the resist 100 of the present invention and the spherical solder ball The joint surface becomes smaller. Accordingly, it is preferable that the diameters of the openings 110a and 120a formed in the resist layers 110 and 120 have appropriate values within the numerical range.

  However, the numerical range is a range for limiting the optimum value at which the effect of the present invention can be achieved, so that the numerical range may slightly deviate from the numerical range as long as it meets the purpose pursued by the present invention. It will be appreciated by those skilled in the art that it can be tolerated.

  On the other hand, as shown in FIG. 2, the openings 110 a and 120 a can be formed such that the side walls thereof are inclined by a manufacturing method of the openings described later. At this time, since the solder ball has a spherical shape, in order to increase the joint surface with the lower portion of the solder ball, the solder ball has a taper shape whose diameter gradually decreases toward the lower side.

  Each of the resist layers 110 and 120 may be formed by curing a resist in a liquid state or a resist film in a dry state.

  Hereinafter, the manufacturing method of the resist 100 of this invention is demonstrated.

  3 to 6 are process diagrams sequentially illustrating a method of manufacturing the resist 100 of the present invention. In the method of manufacturing a resist 100 according to the present invention, first, as shown in FIG. 3, a first resist layer 110 is formed on an upper portion of a substrate 10 on which a pad layer 11 is formed as an outer layer.

  Here, the first resist layer 110 is formed by applying a liquid resist to the upper portion of the substrate 10 using a squeezing method, and then pre-curing the liquid resist. More precisely, after forming the opening in the second resist layer, it can be formed by complete curing (Postcure).

  Since not only the pad layer but also the outer layer circuit wiring are formed on the outer layer of the substrate, the surface of the resist formed by the normal resist forming method has uneven portions depending on the thickness of the pad layer and the outer layer circuit wiring. Have.

  However, as described above, when the squeegee method is used, that is, when the resist in a liquid state is moved while being pressed by a squeegee and transferred to the surface of the substrate 10, the surface becomes flat and the thickness does not vary. One resist layer 110 is obtained. Accordingly, it is possible to further improve the adhesion between the first resist layer 110 and the second resist layer 120 formed in a subsequent process.

  Thereafter, a normal photolithography process, that is, a mask having a predetermined pattern formed on the first resist layer 110 (for example, an artwork film or a glass mask) is brought close to the photo resist, and then irradiated with ultraviolet rays (UV) ( (Exposure stage), by removing an uncured part (part not receiving light) using a developing solution (development stage), as shown in FIG. 4, it has a constant diameter d1 and is formed on the upper surface of the pad layer 11. An opening 110a that exposes a part is formed.

Alternatively, the opening 110a may be formed using various laser methods such as an excimer laser, a YAG laser, and a CO ₂ laser. In this case, due to the characteristics of the laser process, the side wall of the opening has a tapered shape with a diameter that gradually decreases toward the lower side.

  As another method for forming the first resist layer 110, there is a method of bonding a dry resist film, that is, a dry film, to the upper portion of the substrate 10. In the case of a dry film, it is composed of a base film layer (polyester or polyethylene) and a resist layer attached thereto. First, the surface of the resist layer is bonded onto the substrate 10 with heat and pressure using a lamination roll. Then, the first resist layer 110 can be formed by removing the base film.

  When the opening 110a having the constant diameter d1 is processed in the first resist layer 110 as described above, a second resist layer 120 is formed on the first resist layer 110 as shown in FIG. Similar to the first resist layer 110, the second resist layer 120 may be formed by applying a liquid resist by a squeezing method or by bonding a dry film.

  However, when a liquid resist is transferred with a squeegee, the opening 110a formed in the first resist layer 110 is also filled with the liquid resist. Therefore, the second resist layer 120 is applied to the second resist layer 120 using a laser method. When forming the opening, there is an inconvenience that both the resist filled in the opening 110a must be laser processed. Therefore, the second resist layer 120 is more preferably formed by bonding a dry resist film, that is, a dry film to the upper portion of the substrate 10. However, when the photolithography process is used, the liquid resist filled in the opening 110a can be easily removed with a developer so as not to be cured.

  When the second resist layer 120 is formed as described above, the opening 120a is formed at a predetermined position of the second resist layer 120 as shown in FIG. 6 using the photolithography process or the laser process as described above. By forming, the resist 100 of the present invention is completed.

  At this time, the diameter d2 of the opening 120a formed in the second resist layer 120 is larger than the diameter d1 of the opening 110a formed in the first resist layer 110, and is formed in the first resist layer 110. The center of the opening 110a and the center of the opening 120a formed in the second resist layer 120 are positioned on the same vertical line.

  As a result, the resist 100 of the present invention has via holes 100a whose side walls have a stepped shape and the diameter decreases toward the lower portion, as shown in FIG. 6, and as a result, the lower portion of the spherical solder ball. Thus, the bonding strength with the solder ball is further strengthened.

  Further, since the opening is processed for each of the laminated resist layers, the thickness of the resist layer to be removed can be adjusted, thereby reducing the amount of exposure, and the undercut (Under) It is possible to prevent defects such as (Cut) and form a more accurate form of the via hole.

  The above detailed description illustrates the invention. Also, the foregoing is merely illustrative of a preferred embodiment of the present invention and the present invention can be used in a variety of other combinations, modifications and environments. That is, changes or modifications can be made within the scope of the inventive concept disclosed in the present specification, the scope equivalent to the disclosed contents, and / or the skill or knowledge of the industry. The embodiments described above are for explaining the best state in carrying out the present invention, in other states known in the art in using other inventions such as the present invention, and for the invention. Various modifications required in specific application fields and applications are possible. Accordingly, the above detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Also, the appended claims should be construed to include other implementations.

100 resist of the present invention 100a via hole 110 first resist layer 120 second resist layer 110a, 120a opening

Claims (12)

A resist having a via hole formed so as to cover a pad layer formed on the outer layer of the substrate and to expose a part of the upper surface of the pad layer,
The resist is configured in a form in which a resist layer in which openings are formed is laminated in multiple layers,
The opening formed in each resist layer has a smaller diameter than the opening of the resist layer laminated on the upper surface of each resist layer.   The resist according to claim 1, wherein an opening formed in each resist layer has a center located on the same vertical line.   The resist according to claim 1, wherein a diameter of the opening formed in each resist layer is 60 to 80% of a diameter of the opening formed in the resist layer on the upper surface of each resist layer.   The resist according to claim 1, wherein a side wall of the opening formed in each resist layer has an inclined form.   The resist according to claim 1, wherein each resist layer is formed by curing a resist in a liquid state or a resist film in a dry state. A resist having a via hole formed so as to cover a pad layer formed on the outer layer of the substrate and to expose a part of the upper surface of the pad layer,
The resist is
A first resist layer in which an opening having a constant diameter d1 is formed to expose a part of the upper surface of the pad layer;
A resist comprising: a second resist layer bonded to an upper surface of the first resist layer and having an opening having a diameter d2 larger than the diameter d1.   The openings formed in the first and second resist layers have their centers located on the same vertical line, and the diameter of the opening formed in the first resist layer is formed in the second resist layer. The resist according to claim 6, wherein the resist is 60 to 80% of the diameter of the opening. (A) forming a first resist layer on top of a substrate having a pad layer formed on the outer layer;
(B) processing an opening having a constant diameter d1 at a predetermined position of the first resist layer;
(C) forming a second resist layer on top of the first resist layer;
(D) processing the opening having a diameter d2 larger than the diameter d1 of the opening formed in the first resist layer into a predetermined position of the second resist layer.   The first or second resist layer is formed by applying a liquid state resist on the top of the substrate by a squeezing method and then curing the liquid state resist. A method for producing a resist. The first or second resist layer is
The method for producing a resist according to claim 8, wherein the resist is formed by bonding a dry resist film to an upper portion of the substrate.   The opening is formed by selectively exposing and developing the first resist layer or the second resist layer after bringing a mask close to the top of the first resist layer or the second resist layer. Item 9. A method for producing a resist according to Item 8.   The resist manufacturing method according to claim 8, wherein the opening is formed by laser processing.

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