Method for repairing wiring board and method for manufacturing wiring board

Abstract

To provide a repair method by removal of an insulating resin surface and application of conductive paste at a missing portion of a wiring pattern.SOLUTION: The repair method for a wiring board includes the steps of: detecting a missing portion of a wiring pattern; forming banks of resin having height larger than the thickness of the wiring pattern around the wiring pattern including the missing portions; forming a recess in the board by irradiating a surface of the board at the respective missing locations with laser beam; applying a conductive paste between the banks of the resin above the recess in the board to make the conductive paste and the wiring pattern conductive; and curing the conductive paste applied between the banks of the resin.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for repairing a wiring pattern on a wiring board. [Background technology]

[0002] A wiring board used in electronic devices has conductive wiring arranged on the surface of an insulating resin layer. Furthermore, by stacking multiple insulating resin layers with these wirings, a large number of wirings can be accommodated within a board with a smaller surface area.

[0003] Methods for forming wiring on an insulating resin layer include a method in which a conductor is formed over the entire surface of the insulating resin using plating technology or copper foil lamination, and then the conductor is removed using etching technology to leave the shape that will become the wiring (subtractive method), and a method in which a conductor is deposited in the shape that will become the wiring on the surface of the insulating resin using plating technology (additive method).

[0004] The wiring formed by the above method may have a part missing. If the part of the wiring becomes thinner in the width direction due to the missing part, the resistance value will be high although the wiring will still be conductive. If the part of the wiring is completely missing in the width direction due to the missing part, the conductivity will be lost and the wiring will be broken, and in either case, the wiring board will be defective.

[0005] If only one to three wires are missing, there is a technique for repairing the missing parts by applying a conductive material (Patent Document 1).

[0006] This repair technique often uses a fluid conductive paste that contains conductive material. Repairs are performed by applying the conductive paste and then drying and hardening it. Conductive pastes have a high degree of freedom in terms of shape and area depending on the application method, so they are often used as this type of repair method.

[0007] Furthermore, in boards where multiple wiring is arranged side by side on the same plane, the distance between adjacent wiring must be constant, so banks are provided around the area to be repaired to limit the flow of conductive paste. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication 2000-151081 Summary of the Invention [Problem to be solved by the invention]

[0009] Possible causes of the conductive layer being chipped include excessive etching to remove the conductor, poor conductor deposition during the plating process, etc. If there is a factor that prevents the formation of a conductor on the insulating resin surface, the repaired conductor will be chipped even if the repair is made without removing the factor.

[0010] An object of the present invention is to provide a method for repairing a wiring board, which removes the insulating resin surface of missing portions of the wiring pattern of the wiring board and then forms wiring that maintains a constant spacing between adjacent wiring, thereby resulting in a highly reliable wiring board. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides a method for repairing a wiring board, comprising the steps of: detecting a missing portion of a wiring pattern; forming a resin bank around the wiring pattern including the missing portion, the bank having a thickness higher than the thickness of the wiring pattern; irradiating a surface of the substrate at the missing portion with laser light to form a recess in the substrate; applying a conductive paste between the resin banks on the recesses of the base material to electrically connect the conductive paste to the wiring pattern; A step of hardening the conductive paste applied between the resin banks.and, A step of polishing the resin bank and the conductive paste. The method for repairing a wiring board is characterized by comprising the steps of:

[0012] The present invention also provides a method for repairing the above-mentioned wiring board, wherein the conductive paste contains fine particles of copper.

[0013] The present invention also provides a method for repairing the above-mentioned wiring board, characterized in that the depth of the recess in the base material is 4 μm or less.

[0015] The present invention also relates to a method for repairing the above-mentioned wiring board, wherein the step of detecting the missing portion includes a step of creating missing shape data of the wiring pattern at the missing portion, the step of forming a recess in the substrate includes a step of forming a recess in the substrate by scanning and irradiating a laser light onto a surface of the substrate having a shape specified by the missing shape data, and the step of applying the conductive paste to establish electrical continuity between the conductive paste and the wiring pattern includes a step of applying the conductive paste between the resin banks above the recess in the substrate having the shape specified by the missing shape data. Effect of the Invention

[0016] The method for repairing a wiring board according to the present invention has the effect of increasing the reliability of the repaired wiring portion by removing the surface of the substrate at the missing portion of the wiring pattern with laser light to create a recess, thereby increasing the contact area between the substrate and the conductive paste and ensuring adhesive strength.

[0017] In addition, the horizontal range of the resin bank to which the conductive paste is applied is controlled, and the insulating resin is laser-formed into a recess, and then the repaired portion is repaired with the conductive paste, so the wiring can be made thicker. In addition, the amount of conductive paste polished can be increased to make the wiring thinner, so the effect of being able to repair the wiring while accurately adjusting its resistance value is also obtained. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view of a wiring board according to a first embodiment of the present invention. [Diagram 2] 2A to 2C are schematic cross-sectional views showing a manufacturing process of the wiring board according to the first embodiment of the present invention. [Diagram 3] 1A, 1B, and 1C are a cross-sectional view, a first plan view, and a second plan view, illustrating a method for repairing a wiring board according to a first embodiment of the present invention; [Figure 4] FIG. 1A is a first plan view and FIG. 1B is a second plan view for explaining a method for repairing a wiring board according to a first embodiment of the present invention. [Diagram 5] 1A and 1B are a plan view and a cross-sectional view illustrating a method for repairing a wiring board according to a first embodiment of the present invention. [Figure 6] 5A to 5C are cross-sectional views illustrating a method for repairing a wiring board according to a first embodiment of the present invention. [Figure 7] 1A and 1B are a cross-sectional view and a plan view for explaining a method for repairing a broken portion of a wiring board according to a first embodiment of the present invention, and FIG. 1C is an enlarged cross-sectional view taken along the line AA' of FIG. [Figure 8] 5A to 5C are cross-sectional views illustrating a method for repairing a broken portion of the wiring board according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] <First embodiment> A first embodiment of the present invention will be described with reference to Figures 1 to 7. Figure 1 is a schematic cross-sectional view of a wiring board according to the first embodiment of the present invention.

[0020] The wiring board has through-hole wiring 2 formed by through-hole plating in holes formed by penetrating a core substrate 1 such as an organic substrate. The wiring board has a wiring pattern 3a connected to the upper end of the through-hole wiring 2 and a wiring pattern 3b connected to the lower end. An interlayer insulating resin layer 4 having a thickness of 20 μm to 40 μm is formed on the upper layer of the wiring pattern 3a and on the lower layer of the wiring pattern 3b. The wiring pattern 3a is connected to a pad 6 on the upper layer through a via hole 5 penetrating the interlayer insulating resin layer 4.

[0021] Furthermore, the wiring pattern 3b is connected through via holes 5 to a plurality of solder pads 7 arranged in a grid pattern on the lower surface.

[0022] FIG. 1 shows a solder connection structure for mounting a semiconductor chip CH on a wiring board.

[0023] The wiring board has solder bumps 9 on the surface on which the semiconductor chip CH is mounted, and the semiconductor chip CH and the wiring board are electrically connected by bonding the pad portions CHb of the semiconductor chip CH to the solder bumps 9.

[0024] (Method of Manufacturing Wiring Board) FIG. 2 shows the manufacturing process for the above wiring board.

[0025] (Process 1) A through hole 2a is formed in a core substrate 1, which is a laminated resin substrate (FIG. 2(a)).

[0026] (Process 2) A copper electroplating film is formed in the through holes 2a formed in the core substrate 1 to form the through-hole wiring 2 (FIG. 2(b)).

[0027] (Step 3) The through hole 2a in which the through-hole wiring 2 is formed is filled with a filling material 11 to fill the hole (FIG. 2(c)).

[0028] (Step 4) By patterning the copper electroplating film on the front and back surfaces of the core substrate 1, a land pattern 12 that is electrically connected to the through-hole wiring 2, and wiring patterns 3a and 3b that are connected to the land pattern 12 are formed. The wiring patterns 3a and 3b formed in this process are inspected as described below, and any chipped parts of the wiring patterns are repaired using the procedure described below (Figure 2(d)).

[0029] After the land pattern 12 is formed, the wiring patterns 3a and 3b are formed on the interlayer insulating resin layer on the land pattern 12 (FIG. 2(d)). The configuration of the wiring patterns 3a and 3b is not limited to that of FIG. 2(d), and the wiring patterns 3a and 3b can also be formed on the core substrate 1 in a pattern integrated with the land pattern 12.

[0030] (Step 5) After forming an interlayer insulating resin layer 4 on the upper layer of the wiring pattern 3a and on the lower layer of the wiring pattern 3b, holes are formed in the interlayer insulating resin layer 4 to reach the wiring patterns 3a and 3b. Copper electroplating is formed on the holes and the entire surface of the interlayer insulating resin layer 4, and the electroplating layer is etched to form via holes 5, pads 6 on the upper surface, and solder pads 7 on the lower surface. Finally, a solder resist layer 8 is formed to cover the entire front and back surfaces of the wiring board except for the areas where the pads 6 and solder pads 7 are formed (FIG. 2(e)).

[0031] (Step 6) A solder bump 9 is formed on the pad 6, and a solder ball 10 is formed on the solder pad 7.

[0032] (Repair process for missing parts of wiring pattern 3) 3 to 7 show the steps of the method for repairing the wiring pattern formed in the above (step 4).

[0033] (Step 4a) Wiring pattern inspection First, the wiring patterns 3a and 3b in FIG. 2(d) are inspected by an optical inspection device.

[0034] The wiring pattern 3 in Fig. 3(b) is completely disconnected, or the wiring pattern in Fig. 3(c) has a line width narrower than 50%. An optical inspection device (not shown) detects the missing portion 20 and the missing portion 20a. Then, the shape data of the detected disconnection portion 20 and the missing portion 20a and the wiring pattern 3 in the vicinity thereof are stored by an appropriate method.

[0035] (Repairing missing parts of wiring patterns) The procedure for repairing the detected disconnection portion 20 and the missing portion 20a will be described below.

[0036] (Step 4b) Creating repair information including data on the missing wiring on the board The broken portion 20 and the missing portion 20a are inspected in advance by an optical inspection device, and their positions and shape data (missing shape data) are prepared. From this data, the positions to be repaired and the sizes to be repaired are listed. In addition, the depth to be processed by the laser and the amount to be removed by polishing are determined in advance from the design data. The depth to be processed by the laser is set to be in the range of approximately 2 to 4 μm.

[0037] (Step 4c) 4(a) and 4(b) show the state in which the resin bank 22 has been formed, and the bank 22 has been formed along both ends of the wiring pattern 3 in the vicinity of the disconnection site 20 so that the disconnection site 20 is surrounded by the bank 22 and the wiring pattern 3. The bank 22 was formed by discharging a highly viscous liquid ultraviolet curing resin using a dispenser with a rectangular outlet opening, and then curing the resin with an ultraviolet lamp.

[0038] As the ultraviolet curing resin for the banks 22, a dry film type resin may be applied along both ends of the wiring pattern 3.

[0039] The resin bank 22 is formed to be higher than the thickness of the wiring pattern 3 (FIG. 5(b)).

[0040] (Step 4d) 6 shows a process of removing the interlayer insulating resin layer 4 at the disconnection point 20 to a uniform depth using a laser. A recess 23 in the substrate is formed by scanning and irradiating the surface of a substrate portion 21 having a shape specified by data on the missing shape of the wiring with laser light L.

[0041] By irradiating the laser light L, not only is the surface of the recesses 23 of the base material roughened, but also foreign matter that reduces the adhesion strength is removed.

[0042] (Step 4e) Figure 7 shows the process of applying conductive paste 41. Using a dispenser 40, conductive paste 41 is applied to recesses 23 of the substrate formed in a shape specified by the wiring loss shape data (Figure 7(a)). At this time, conductive paste 41 is applied to the extent that it reaches the top of banks 22 (Figures 7(b) and (c)).

[0043] In this embodiment, the conductive paste 41 used for repair contains copper fine particles, which is the same material as the conductor, but it is also possible to use a conductive material contained in the conductive paste 41 that contains copper fine particles with a silver coating on the surface.

[0044] (Process 4f) In order to harden the applied conductive paste 41, the entire substrate was heated in a nitrogen atmosphere at 150° C. for 15 minutes. This heating step can also be performed locally.

[0045] (Process 4g) The upper surface of the hardened conductive paste 41 is polished with a belt-type polishing device (not shown) to remove excess conductive paste 41 (FIG. 8).

[0046] This process makes it possible to finish the wiring height of the wiring pattern 3 in the repaired portion to a determined height (thickness) and uniformly.

[0047] Next, the banks 22 are peeled off using an appropriate method. If the banks 22 can be used to protect the wiring, they can be left as they are without being peeled off. [Explanation of symbols]

[0048] 1. Core substrate 2. Through-hole wiring 2a...Through hole 3, 3a, 3b... Wiring pattern 4. Interlayer insulating resin layer 5. Via hole 6... Pad 7...Solder pad 8. Solder resist layer 9. Solder bumps 10. Solder ball 11...Hole filling material 12... Pad 20. Breakage point 20a: Missing part 21...Base material part 22. Embankment 23....Recess in substrate 30 Laser irradiation device 40... Dispenser 41...Conductive paste CH···Semiconductor chip CHb Pad L...Laser light

Claims

1. A method for repairing a wiring board, comprising the steps of: detecting a missing portion of a wiring pattern; forming a resin bank around the wiring pattern including the missing portion, the bank having a thickness higher than the thickness of the wiring pattern; irradiating a surface of the substrate at the missing portion with laser light to form a recess in the substrate; applying a conductive paste between the resin banks on the recesses of the base material to electrically connect the conductive paste to the wiring pattern; hardening the conductive paste applied between the resin banks; a step of polishing the resin bank and the conductive paste;

2. 2. The method for repairing a wiring board according to claim 1, wherein the conductive paste contains fine particles of copper.

3. 3. The method for repairing a wiring board according to claim 1, wherein the depth of the recess in the base material is 4 [mu]m or less.

4. 4. The method for repairing a wiring board according to claim 1, wherein the step of detecting the missing portion includes a step of creating missing shape data of the wiring pattern at the missing portion, the step of forming a recess in the base material includes a step of forming a recess in the base material by scanning and irradiating a laser beam onto a surface of the base material having a shape designated by the missing shape data, The step of applying the conductive paste and electrically connecting the conductive paste to the wiring pattern includes a step of applying the conductive paste between the resin banks on the recess of the base material having a shape specified by the missing shape data.

13. A method for repairing a wiring board comprising the steps of:

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