Patent Application
20090294162
This application claims the benefit of Korean Patent Application No. 10-2008-0051817, filed with the Korean Intellectual Property Office on Jun. 2, 2008, the disclosure of which is incorporated herein by reference in its entirety.
1. Technical Field
The present invention relates to a printed circuit board and a manufacturing method thereof.
2. Description of the Related Art
Recently, with the development of the semiconductor technology, integration of a semiconductor package and demands for more functions, not only one chip but also multiple chips and semiconductor chips, such as a capacitor and a resister, are frequently mounted together on a substrate having a semiconductor chip mounted thereon. While use of flip chip packages (FCCSP) as a printed circuit board mounting semiconductor chips is rapidly increasing for the purpose of making electronic products smaller, there is a limit in reducing the size of a semiconductor package including the flip chip package (FCCSP) product, due to the flow control problem of an underfill solution used to mount a semiconductor chip.
For example, when mounting a chip on the flip chip package (FCCSP) product, it is difficult to effectively control the flow of the underfill solution injected between the printed circuit board and the semiconductor chip. The injected underfill solution penetrates through a pad, which is necessary for wire-bonding or solder ball junction. For that reason, the pad and the semiconductor may be contaminated.
The present invention provides a printed circuit board and a manufacturing method thereof that can prevent a pad from being contaminated and control the flow of an underfill solution when injecting the underfill solution by forming a dam by means of an inkjet method.
An aspect of the present invention features a method of manufacturing a printed circuit board having an electronic component mounted thereon. The method of manufacturing a printed circuit board in accordance with an embodiment of the present invention can include: providing a substrate having a circuit pattern and a pad formed on one side thereof; forming a solder resist layer on one side of the substrate so as to expose the pad; and forming a dam on the solder resist layer with an inkjet printing method so as to control a flow of an underfill solution injected between the substrate and the electronic component, the dam being disposed at a position corresponding to where the electronic component is mounted.
A cross-section of the dam can have a convexly curved shape in the upper part thereof.
The forming of the solder resist layer on one side of the substrate can use an inkjet printing method.
Prior to the forming of the dam, plasma-treating the surface of the solder resist layer can be further performed.
The forming of the dam can include printing polymer ink on the solder resist layer with an inkjet printing method; and hardening the polymer ink
The polymer ink can include an acrylate-based compound or wax.
After the forming of the solder resist layer on one side of the substrate, further included can be forming of a dam pillar by printing a conductive material on the pad with an the inkjet printing method, which connects the pad to the electronic component.
The forming of the dam and the forming of the dam pillar are performed in a same process. The dam pillar is taller than the dam.
Another aspect of the present invention features a printed circuit board having an electronic component mounted thereon. The printed circuit board in accordance with an embodiment of the present invention can include: a substrate, having a circuit pattern and a pad formed on one side thereof; a solder resist layer, formed on one side of the substrate so as to expose the pad; and a dam, formed on the solder resist layer by an inkjet printing method and disposed at a position corresponding to where the electronic component is mounted so as to control a flow of an underfill solution injected between the substrate and the electronic component.
A cross-section of the dam can have a convexly curved shape in the upper part.
The solder resist layer can be formed by the inkjet printing method.
The printed circuit board mentioned above can be formed by printing a conductive material on the pad with an inkjet printing method, and can further include a dam pillar connecting the pad to the electronic component.
The dam pillar can be taller than the dam.
Since there can be a variety of permutations and embodiments of the present invention, certain embodiments will be illustrated and described with reference to the accompanying drawings. This, however, is by no means to restrict the present invention to certain embodiments, and shall be construed as including all permutations, equivalents and substitutes covered by the spirit and scope of the present invention. In the following description of the present invention, the detailed description of known technologies incorporated herein will be omitted when it may make the subject matter unclear.
The terms used in the description are intended to describe certain embodiments only, and shall by no means restrict the present invention. Unless clearly used otherwise, expressions in the singular number include a plural meaning. In the present description, an expression such as “comprising” or “consisting of” is intended to designate a characteristic, a number, a step, an operation, an element, a part or combinations thereof, and shall not be construed to preclude any presence or possibility of one or more other characteristics, numbers, steps, operations, elements, parts or combinations thereof.
Hereinafter, embodiments of a printed circuit board and a manufacturing method thereof will be described in detail with reference to the accompanying drawings. In description with reference to accompanying drawings, the same reference numerals will be assigned to the same or corresponding elements, and repetitive descriptions thereof will be omitted.
Provided according to an embodiment of the present invention is the substrate 10 having the circuit pattern 12 and the pad 14 formed on one side thereof (S100). The circuit pattern and the pad can be formed on an insulating substrate. The circuit pattern and the pad are designed according to transfer flow of an electronic signal required by the substrate 10. That is, the circuit pattern and the pad are made of a conductive material, playing the role of transferring an electronic signal and making an electrical connection.
Then, the solder resist layer 20 is formed on one side of the substrate 10, as illustrated in
The solder resist layer 20 is formed such that the pad 14 requiring electrical connection to the outside can be exposed to the outside. The pad 14 is joined with an electronic component by a solder ball 50 or is wire-bonded to an electronic component. Accordingly, an external electronic component can be electrically connected to the circuit pattern 12 inside the substrate 10 through the pad 14 exposed to the outside.
According to an embodiment of the present invention, as illustrated in
As in an embodiment of the present invention, the solder resist layer 20 can be precisely formed on a desired area of the substrate only, by forming the solder resist layer 20 through the inkjet printing method. According to this embodiment, the solder resist ink can be precisely jetted on the parts other than the pad 14, by using the inkjet head 40. Accordingly, it is possible to precisely expose the fine pad designed not to be covered by the solder resist layer 20.
While an embodiment of the present invention describes the process of forming the solder resist layer 20 through the inkjet printing method with reference to
In forming a dam 30 after forming the solder resist layer 20, according to an embodiment of the present invention, the surface of the solder resist layer 20 can be treated by plasma before forming the dam (S300). Treating the surface can prevent a possible height difference in the dam. The surface treatment process of the solder resist layer will be described later with reference to
The dam 30 is formed on the solder resist layer 20, as illustrated in
That is, the dam 30 can be formed at a position corresponding to the position of the mounted electronic component, such that the underfill solution, which is injected to secure the connection between the electronic component and the substrate, is prevented from overflowing. When the dam is formed outside the electronic component, the dam performs a function of preventing the pad 14 exposed to the outside of the dam from being contaminated by the underfill solution during the process of injecting the underfill solution.
When the dam 30 is formed inside the electronic component, the dam can control how low the underfill solution is injected in the electronic component. That is, if the property of the electronic component or the substrate does not require that the underfill solution be injected into the entire surface of the lower side of the electronic component, the dam can be formed inside the electronic component.
The dam 30 is designed to be formed outside or inside the electronic component with the consideration of the mounting position of the electronic component and the injecting position of the underfill solution. The dams can be also designed to be formed both outside and inside the electronic component.
According to this embodiment of the present invention, the dam 30 is formed as follows, as illustrated in
The polymer ink is jetted through the inkjet head 40 by a bubble jet method or piezoelectric jet method. In the piezoelectric jet method, the ink is jetted by using a piezoelectric substance, which vibrates with a supplied voltage. That is, the piezoelectric jet method uses a principle that a piezoelectric substance lengthened by the supplied voltage gives a pressure to the ink, thereby jetting the ink to the outside. In the bubble jet method, the ink is jetted by vaporizing the water inside the ink through instantaneous high temperature from a heating plate.
The polymer ink used for inkjet printing in order to form the dam 30 can include an acrylate-based compound or wax. Ink containing between 70 and 100 weight percent of the acrylate-based compound or wax can be used.
After the polymer ink is printed in the shape of the dam 30, the printed polymer ink is hardened. The polymer ink is hardened by being exposed to ultraviolet rays or heat. The polymer ink can be also hardened by being exposed to both heat and the ultraviolet rays.
Through the method described above, the dam 30 having various patterns and heights can be made as illustrated in
In a forming process of a dam 30 in accordance with an embodiment of the present invention, it is possible to adjust the ingredient and concentration of the polymer ink used in the inkjet printing method and the amount of the ink jetted from the inkjet head 40 in accordance with design intent.
After the dam 30 is formed, the height and width of the dam is changeable according to the height of the electronic component to be mounted and the property of the underfill solution. Therefore, there can be less restriction on how the dam is designed when manufacturing the printed circuit board.
Referring to
The dam 30 can be made of a material that is repulsive to the underfill solution. The material that is repulsive to the underfill solution is added to the polymer ink for forming the dam. The dam 30 formed in such a manner comes in contact with the underfill solution. Since the dam has a section having a convexly curved shape in the upper part, the area repulsed between the underfill solution and the dam can be increased.
Forming the dam 30 to be repulsive to the underfill solution and maximizing the repulsion area between the underfill solution and the dam can effectively prevent the underfill solution from overflowing.
According to an embodiment of the present invention, the surface 70 of the solder resist layer 20 having a dam formed thereon can be treated by plasma before forming the dam 30. The solder resist layer surface treatment process S300 will be described with reference to the following
The surface of the solder resist layer 20 formed on one side of the substrate 10 is made rough, as illustrated in
Therefore, a surface treatment process for reducing the roughness of the surface of the solder resist layer 20 is performed as illustrated in
Subsequently, the height difference of the dam can be further prevented by forming the dam 30 on the surface-treated solder resist layer 20, as illustrated in
Meanwhile, further performed after the dam 30 is formed can be a process of restoring the surface of the solder resist layer 20 having changed physiochemical property through the surface treatment process mentioned above. The surface is restored physicochemically by use of ultraviolet (UV) energy, heat energy or nitrogen (N2) gas in the manner similar to the surface treatment process mentioned above. These procedures can be used to restore the property of the solder resist layer 20 having no dam formed thereon, and to prevent the effect of the plasma treatment, which may occur when mounting the electronic component or injecting the underfill solution.
According to an embodiment of the present invention, after forming the solder resist layer on the substrate 10, a dam pillar 32 can be formed on the pad 14. The dam pillar 32 can be formed by the inkjet printing method, which is used to form the dam.
The process of forming the dam pillar 32 can be the same as that of forming the dam. In other words, both processes are performed by adjusting the amount of ink jetted by the inkjet head 40 through the same inkjet printing method. Accordingly, the dam pillar 32 can be formed on the exposed pad 14 having a taller shape than that of the dam 30 in the middle of or at the end of the dam 30. The dam pillar 32 can be also independently formed and separated from the dam 30.
The dam pillar 32 is formed taller than the dam 30 such that it connects the electronic component to the pad. According to this embodiment of the present invention, the dam pillar is made of a conductive material, which is connected to the electronic component and formed on the pad 14. That is, the dam pillar 32 can be formed by printing the conductive material on the pad with the inkjet printing method. Therefore, the dam pillar 32 is capable of electrically connecting the electronic component to the substrate 10.
When forming the dam, a greater amount of conductive ink is jetted on the exposed pad 14. The dam pillar can be formed by hardening the conductive ink. The dam pillar supports the electronic component and connects the electronic component to the substrate 10.
Hereinafter, a printed circuit board according to an embodiment of the present invention will be described with reference to
As illustrated in
According to another embodiment of the present invention, as illustrated in
As illustrated in
In the illustrations of
While certain embodiments of the present invention have been described, it shall be understood by those skilled in the art that various modifications and permutations of the present invention are possible without departing from the spirit and scope of the present invention as defined by the appended claims.
Numerous embodiments other than the embodiments described above are included within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2008-0051817 | Jun 2008 | KR | national |
