KR20040079500A - Method Of Forming Window-Slit Of A Printed Circuit Board - Google Patents

Abstract

PURPOSE: A method for forming a window slit of a PCB is provided to prevent cracks such as a tie bar burr and a glass fiber burr by adding a punching process to conventional processes. CONSTITUTION: A PCB including a plurality of solder ball pads is prepared(S1000). A plurality of tie bars connected to a power line through a bond pad are plated in parallel among each group of the solder ball pads(S2000). A window slit is formed by performing a punching process along the power line(S3000). A finishing process is performed by shaving a cut side of the window slit(S4000).

Description

Method of Forming Window Slit of Printed Circuit Board {Method Of Forming Window-Slit Of A Printed Circuit Board}

The present invention relates to a method for preventing burrs generated around the slit when forming a window slit on the printed circuit board for a semiconductor package, and more particularly, a stem of a lead frame method. The present invention relates to a method of forming a window slit on a printed circuit board which can minimize cracks such as burrs around the window slit by shaping the punching surface after forming a window slit on the printed circuit board using a punching step used in the ping process.

In recent years, due to the light and short size of the electronics industry, high integration of semiconductors is required, unlike conventional semiconductor package processes. Therefore, semiconductor package technology also requires a process that can realize high reliability, such as a chip scale package (CSP) process. .

Interconnection between double boards and semiconductors, and Ball Grid Array (BGA) types using solder balls are of interest, and wBGA (windowing) that performs a wire bonding process under the substrate. Ball Grid Array) type is being developed.

In order to perform the wBGA (window ball grid array) type semiconductor package process, window silt processing in which electrical contact between the die and the substrate is possible should be performed in advance, and in the present invention, one of the main methods of slit processing This paper proposes a technique for preventing cracks around the slit using a punching process.

1 is a plan view illustrating a window slit of a printed circuit board formed through a printed circuit board and a routing process, and FIG. 2 is a partially enlarged view taken along line A of FIG. 1.

As shown in FIG. 1, the bond pads 1b, power lines 1d, and tie bars 1c, which are plated to be electrically connected to each other, are respectively formed on the upper portion of the printed circuit board 1 before the window slit 3 is formed. It is formed. Thereafter, the window slit 3 was formed by punching along the power line 1d of the printed circuit board 1.

The above method is a method of forming a slit in a small sized substrate together with an etch-back process using a conventional routing process.

Routing process using the etch back process is to remove the tie bar, which is an electrical connection line before forming the window slit, a drilling process to dig a hole into which the router bit is to be formed, and finally, a router. The process proceeds to picking the slit 3 with a bit.

At this time, the etch-back process may leave copper residue on the surface of the wire bond pad after removing the tie bar, and the surface roughness is increased during gold plating. A problem may occur in which wires are not bonded between substrates.

In addition, the hole drilling method using a drilling process rotates at a high speed into the substrate, so that cracks such as tie bars and burrs 3a and glass fibers and burs 3b are formed around the holes. In the routing process, a problem arises in that the size of the slit 3 due to a crack is not adjusted or a clean surface of the crack is not formed.

Accordingly, the present invention has been made in view of the above problems, and a first object of the present invention is a tie bar-burr generated around a slit when a slit is formed on an upper portion of a printed circuit board for a semiconductor package. And to provide a window slit forming method of a printed circuit board that can minimize cracks, such as glass fiber-burr.

The second object of the present invention is to form a window slit on a printed circuit board by using a punching step used in a lead frame stamping process, and then, by shaving the cut surface of the window slit, adding a step of surrounding the window slit. It is to provide a method of forming a window slit of a printed circuit board that can minimize cracks.

The object of the present invention is to prepare a printed circuit board formed by forming a group of a plurality of solder ball pads (S1000), and parallel plating the tie bar connected to the power line with a bond pad between each group of the solder ball pads And forming a window slit by punching along the power line (S3000) and shaving and trimming the cut surface of the window slit (S4000) of the printed circuit board. It is achieved by the window slit forming method.

In the plating process step (S2000), the width of the tie bar is preferably treated at 60% of the width of the bond pad.

In addition, in the punching step (S3000), it is preferable to punch 90 to 97% of the desired window slit.

In addition, in the finishing step (S4000), it is preferable to shave 3 to 10% of the desired window slit corresponding to the punching ratio of the window slit.

In the finishing step (S4000), it is preferable to shave using a router bit.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and the preferred embodiments associated with the accompanying drawings.

1 is a plan view showing a front and rear slit of a printed circuit board formed through a conventional punching process,

FIG. 2 is a partially enlarged view taken along line A of FIG. 1;

3 is a flowchart illustrating a step-by-step method of forming a window slit of a printed circuit board of the present invention;

4 is an enlarged view of a power line, a tie bar, and a bond pad electroplated on a printed circuit board of the present invention;

5 is a conceptual diagram illustrating a finishing step according to the flowchart of FIG. 3;

6 is a conceptual diagram illustrating a punching and finishing area according to the flowchart of FIG. 3;

FIG. 7 is a conceptual diagram illustrating a progress direction of a router bit of a finishing step according to the flowchart of FIG. 3.

<Description of the symbols for the main parts of the drawings>

1: printed circuit board 1a: solder ball pad

1b: Bond Pad 1c: Tie Bar

1d: power line 3: window slit

3a: tie-bar bur 3b: fiberglass-bur

10: printed circuit board 10a: solder ball pad

10b: bond pad 10c: tie bar

10d: power line 11: window slit

20: Router Bit

Hereinafter, a method of forming a window slit of a printed circuit board according to the present invention will be described with reference to the accompanying drawings.

3 is a flowchart illustrating a step-by-step method of forming a window slit of a printed circuit board of the present invention, and FIG. 4 is an enlarged plan view of a power line, a tie bar, and a bond pad electroplated on the printed circuit board of the present invention.

As shown in FIG. 3, the method of forming the window slit 11 is completed through a punching step and a finishing step.

To this end, first, a plurality of solder ball pads 10a are prepared to have a printed circuit board 10 formed in parallel with a predetermined interval along both longitudinal directions so as to form a group. At this time, the outer surface of the printed circuit board 10 is coated with a special coating (S1000).

In addition, each bond ball pad 10a is electrically connected to each bond pad 10b by performing a gold plating process on the tie bars 10c connected to the power lines 10d in parallel with the bond pads 10b. . At this time, as shown in Figure 4, it is preferable to treat the width (T) of the tie bar (10c) to about 60% or more, less than 100% with respect to the width (t) of the bond pad (10b). In addition, it is preferable that the width T of the tie bar 10c does not exceed 100% of the width t of the bond pad 10b.

This is because when the width of the tie bar 10c is less than 60%, the traction force with the printed circuit board 10 is weakened, so that the tie bar 10c may be lifted in the finishing step. This phenomenon is due to the frictional force due to the rotation of the router bit 20 in the finishing step (S2000).

Thereafter, the window slit 11 is formed by punching along the length direction of the power line 10d, wherein the size of the window slit 11 after punching is about 90 to about the desired window slit 11. It should be about 97% in size.

This is due to the deviation that may occur between the printed circuit board 10 and the punching mold. In addition, according to the tolerance of the mold for forming the window slit (11).

In addition, if the punched window slit 11 is 97% or more than the size of the desired window slit 11, the shaving operation is not sufficiently performed in the finishing step of the various tie bar-burrs 3a and This is due to the disadvantage that cracks such as glass fiber-burr 3b are not completely removed.

However, if the punched window slit 11 is 90% or less than the size of the desired window slit 11, there are more areas to be shaved in the finishing step, so that the tie bar-ber 3a during the shaving operation. ) Is likely to occur, and there may be a crack such as cracking of the printed circuit board 10. (S3000)

Finally, the cut surface of the window slit 11 formed on the printed circuit board 10 is shaved and finished.

In the above finishing method, the router bit 20 is rotated to minimize cracks such as the tie bar burr 3a and the glass fiber burr 3b generated in the punching step for forming the window slit 11. To trim the cut surface.

At this time, it is preferable that the shaving (face value) processing proceeds to 3 to 10% of the desired window slit 11 corresponding to the punching ratio of the window slit 11.

This is because if the shaving is less than 3%, cracks such as burrs 3a and 3b formed on the cut surface of the window slit 11 cannot be completely removed.

If the shaving process is 10% or more, it takes a long time, or because the base material is deformed due to the temperature rise of the processing surface due to the frictional force during processing, there is a disadvantage that the precision is inferior.

5 is a conceptual diagram illustrating a finishing step according to the flowchart of FIG. 3.

As shown in Figure 5, in the finishing step (S4000), cracks such as tie-bar bur (3a) and glass fiber bur (3b) generated in the punching step for forming the window slit 11 Insert the router router 20 is rotated to minimize the trimming the cut surface.

At this time, the router bit 20 is preferably the end mill blade is formed in one direction suitable for shaving.

6 is a conceptual diagram illustrating regions of punching and finishing according to the flowchart of FIG. 3.

As shown in FIG. 6, a window slit 11 is formed along the longitudinal direction of the power line 10d plated on the printed circuit board 10. At this time, the window slit 11 formed in the punching step is preferably punched at about 90 to 97% with respect to the desired window slit 11 for the finishing step.

In the finishing step thereafter, only about 3 to 10% of the desired window slit 11 is processed corresponding to the punching ratio of the window slit 11 to remove cracks such as burs 3a and 3b. The slit 11 can be formed.

FIG. 7 is a conceptual diagram illustrating a progress direction of a router bit in the finishing step according to the flowchart of FIG. 3.

As shown in FIG. 7, in the finishing step, the insertion direction of the router bit 20 moves from the center to the inner wall of the cut surface of the window slit 11 to perform shaving. This may solve the problem that the router bit 20 is in direct contact with the printed circuit board 10 and cracks are formed, such as cracking.

In addition, the progress direction of the router bit 20 is preferable to proceed in the clockwise direction in consideration of the blade direction, the rotation direction of the end mill.

As described above, in the method of forming a window slit of a printed circuit board, by adding a punching process to an existing process, there is a feature that can prevent cracks such as tie bars and glass fibers and burrs in the existing drilling process. .

In addition, by forming the slit by punching first, and shaving the slit cutting surface punched second, there is a feature that can prevent the cracks around the slit and at the same time complete the product.

In addition, by adding only the punching equipment to the existing equipment, there is an advantage that can bring out the maximum effect at the minimum cost.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

Claims (5)

In the manufacturing method of a printed circuit board, Preparing a printed circuit board 10 having a plurality of solder ball pads 10a formed in a group (S1000); Parallel plating the tie bars (10c) connected to the power lines (10d) with bond pads (10b) between the groups of the solder ball pads (10a) (S2000); Punching along the power line (10d) to form a window slit (11); And Shaving the cut surface of the window slit (11) and finishing (S4000); forming a window slit of a printed circuit board, characterized in that it comprises a. The method of claim 1, In the plating process step (S2000), the width of the tie bar (10c) to 60% to 100% of the width of the bond pad (10b) to process the window slit forming method of the printed circuit board. The method of claim 1, In the punching step (S3000), 90 to 97% of the desired window slit (11) is punched. The method of claim 1, In the finishing step (S4000), shaving of 3 to 10% of the desired window slit (11) corresponding to the punching ratio of the window slit (11). The method according to claim 1 or 4, In the step of finishing (S4000), the router bit (20) shaving using an end mill, characterized in that the window slit forming method of the printed circuit board.