JP2001244299A - Wiring board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which can prevent deviation in position of a chip before soldering is completed by keeping force for holding a mounted chip while maintaining a gap necessary between the chip and the substrate, and also provide a method of manufacturing the same. SOLUTION: A fine solder paste is screen-printed on lands 12 of a substrate 11. The screen-printed substrate 11 is reflowed and heated to supply solder 14 onto the lands 12. After printing a thermosetting epoxy resin paste in a part of the substrate 11 inside the lands 12, a heat treatment is performed to form resin columns 15. On this substrate 11, a bare chip 17 having solder bumps 18 is mounted. Thereafter, the substrate 11 mounted with the bare chip 17 is reflowed and heated to solder the bare chip 17 on the lands 12 and mount the bare chip 17 on the substrate 11. Then, underfill resin 20 is supplied between the bare chip 17 and the substrate 11 and then a heat treatment is performed to cure the resin 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wiring board used in a surface mounting process and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a flip chip mounting method using eutectic solder bumps, there are a reflow soldering method and a method of adjusting a gap between a chip and a substrate while mounting with a heating head. In the method using the heating head, since the heating head performs not only mounting but also heating soldering to cooling, the machine tact becomes much longer than the reflow soldering method. Further, in the method using the heating head, the number of required equipment is large, and the equipment cost is extremely high.

[0003] Therefore, for the flip chip mounting,
It is desirable to adopt a reflow soldering method. However, in the case of performing the flip chip mounting using this reflow soldering method, the mounting can be performed without any problem by using the high melting point solder bump. However, the use of the eutectic solder bump causes the following problems.

[0004]

That is, for example, as shown in FIG. 5, when a chip 24 is mounted on a land 22 formed on a substrate 21 via a solder bump 23, a soldering process is required. The solder bumps 23 are melted by the heating, are crushed by the weight of the chip 24, and the gap between the chip 24 and the substrate 21 is reduced (20-3).
5 μm).

As a result, the underfill resin supplied between the substrate 21 and the chip 24 cannot be injected. Depending on the selection of the viscosity of the flux used at the time of soldering, this phenomenon becomes more remarkable, and a bridge may occur between the solder bumps 23.

[0006] If the viscosity of the flux is reduced, this tendency can be avoided. However, if the viscosity is low, the holding force of the mounted chip 24 becomes weaker, and the chip 24 becomes weaker before the soldering is completed. There is a problem that a position shift occurs.

The present invention has been made in view of the above circumstances, and maintains a required gap between a chip and a substrate, and also maintains a force for holding a mounted chip, thereby completing soldering. An object of the present invention is to provide a wiring board and a method for manufacturing the wiring board, which can prevent the displacement of the previous chip.

[0008]

According to the present invention, there is provided a substrate body having element mounting lands formed thereon, a semiconductor element mounted on the element mounting lands, and a semiconductor device mounted between the substrate body and the semiconductor element. A columnar member provided to maintain a predetermined gap between the substrate main body and the semiconductor element; and a resin member filled between the substrate main body and the semiconductor element. Provide a wiring board.

According to this configuration, since the columnar member supports the semiconductor element, it is possible to prevent the weight of the semiconductor element from being concentrated on the joint between the substrate and the semiconductor element. Thereby, the bonding member at the bonding portion between the substrate and the semiconductor element is not crushed, and the required gap between the semiconductor element and the substrate can be maintained. In addition, it is possible to maintain the force for holding the mounted semiconductor element and prevent the semiconductor element from being displaced before soldering is completed.

In the wiring board according to the present invention, it is preferable that the columnar member is made of the same kind of resin as the resin member. According to this configuration, compatibility between the resin member and the columnar member is improved, and sufficient reliability can be secured.

According to the present invention, there is provided a step of forming a columnar member on a portion other than the element mounting land of the substrate body having the element mounting land, and the step of mounting the semiconductor element on the element mounting land while supporting the columnar member. A method for manufacturing a wiring board, comprising: a step of mounting on a substrate; and a step of filling a resin member between the substrate body and the semiconductor element.

According to this method, the gap required between the semiconductor element and the substrate is maintained, and the force for holding the mounted semiconductor element is maintained, so that the position of the semiconductor element before soldering is completed. A wiring board that can prevent displacement can be obtained.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 (a)-
2C and 2A to 2C are cross-sectional views illustrating a method for manufacturing a wiring board according to an embodiment of the present invention.

In this embodiment, the diameter is 80 μm and the height is 7
A case will be described in which a 100-pin bare IC (semiconductor element) having a chip size of 8 mm × 0.3 mm and having a 0 μm eutectic solder (melting point: 183 ° C.) bump on an aluminum pad is mounted on a flip chip.

As shown in FIG. 1A, a fine particle solder paste is screen-printed on a land 12 formed on the substrate 11, and the printed substrate 11 is reflow-heated to perform solder pre-coating on the land 12. Solder 14 was supplied.
A resist 13 is formed on a portion other than the land 12 on the substrate 11.

Next, as shown in FIG. 1B, a thermosetting epoxy resin paste was printed inside the land 12. The metal screen used at this time has a thickness of 40μ.
It had four openings of 1 mm in diameter and 2 mm pitch. The print pattern is set so as to have a spread capable of stably supporting the bare chip, and not to touch the land 12 even if the printing is shifted.

After printing, the substrate 11 was subjected to a heat treatment at 100 ° C. for 10 minutes to harden the epoxy resin paste to form the resin pillar 15. This resin pillar 1
The height of No. 5 was 40 ± 5 μm from the surface of the resist 13. In this manner, as shown in FIG. 3, four resin pillars 15 were provided inside the land 12 on which the bare chip was mounted.

The height of the resin pillar 15 is preferably set to be equal to or less than the gap between the bare chip to be mounted and the substrate 11, and specifically, the height of the bump of the bare chip is maximized. Although the shape of the resin pillar 15 depends on the chip size of the bare chip, it is preferable that the resin pillar 15 be shaped such that the bare chip is not tilted to a region facing the active surface of the bare chip and is stable. The size of the resin pillar 15 is
In order not to lower the reliability of the underfill resin described later, it is desirable to set the minimum necessary for supporting the bare chip.

Next, as shown in FIG. 1C, a flux 16 having a viscosity of 50 Pa · s was printed off-contact using a mesh screen having an emulsion thickness of 30 μm so as to completely cover the lands 12. The height of the flux 16 after printing was 25 ± 5 μm.

Next, as shown in FIG. 2A, a bare chip 17 having the above-mentioned solder bumps 18 was mounted on the substrate 11 in such a manner that the solder bumps 18 were aligned with the lands 12. Thereafter, as shown in FIG. 2B, the substrate 11 on which the bare chip 17 was mounted was subjected to reflow heating, the bare chip 17 was soldered to the land 12, and the bare chip 17 was mounted on the substrate 11. At this time,
The resin pillar 15 supports the bare chip 17 and prevents the solder 19 from being crushed.

Next, the flux at the solder joint was removed by washing and then dried. After that, as shown in FIG.
S epoxy resin paste to bare chip 17 and substrate 1
1 and heat-treated at 150 ° C. for 4 hours to cure the epoxy resin.

When the open / short check is performed on the board 11 on which the bare chip 17 is mounted as described above, the conventional wiring board without such resin printing produces as much as 5 to 20%. It was confirmed that no solder bridge had occurred. Further, when the cross section of the solder joint portion was observed, it became as shown in FIG. 4, the gap between the bare chip 17 and the substrate 11 became an appropriate value of 50 to 60 μm, and voids of the underfill resin 20 were also observed. Did not.

As described above, in the wiring board according to the present invention, since the pillar for supporting the chip is provided on the board side in advance, even if the bump is melted by the reflow temperature, the gap can be secured without being crushed, and the solder bridge and the underside can be secured. It is possible to avoid occurrence of troubles such as unfilling of the fill resin.

In addition, since the printing of the resin paste was performed using a metal screen instead of a mesh screen, no beard-like projections were generated after printing, and the active surface of the bare chip was not damaged. Furthermore, since the same type of epoxy resin as the underfill resin was used for the resin pillar,
Even in the heat cycle test at -25 ° C to 125 ° C, 2
No defects occurred up to 000 cycles, and sufficient reliability was secured.

The present invention is not limited to the above embodiment, but can be implemented with various modifications. For example, the material, dimensions, and the like of each member are not limited to the above embodiment, and can be variously changed.

[0026]

As described above, the wiring board of the present invention is provided between the semiconductor element mounted on the element mounting land of the substrate main body and the substrate main body, with a predetermined distance between the substrate main body and the semiconductor element. Since the columnar member that holds the gap is provided, the gap required between the semiconductor element and the substrate is maintained, and the force that holds the mounted semiconductor element is maintained. The displacement of the element can be prevented.

Further, according to the method of manufacturing a wiring board of the present invention, a columnar member is formed in a portion other than the element mounting land, and the semiconductor element is mounted on the element mounting land while being supported by the columnar member. Since the resin material is filled between the board body and the semiconductor element, the necessary gap between the semiconductor element and the board is maintained, and the soldering is completed while maintaining the holding force of the mounted semiconductor element. Thus, it is possible to obtain a wiring board that can prevent the semiconductor element from being displaced before the wiring.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views illustrating a first half of a method of manufacturing a wiring board according to an embodiment of the present invention;

FIGS. 2A to 2C are cross-sectional views illustrating the latter half of a method for manufacturing a wiring board according to an embodiment of the present invention;

FIG. 3 is a view showing a state in which resin columns are formed on the wiring board of the present invention.

FIG. 4 is a view showing a solder joint portion of the wiring board of the present invention.

FIG. 5 is a view showing a solder joint portion of a conventional wiring board.

[Explanation of symbols]

11: substrate, 12: land, 13: resist, 14, 1
9 solder, 15 resin pillar, 16 flux, 17 bare chip, 18 solder bump, 20 underfill resin.

Claims (3)

[Claims] A substrate body on which an element mounting land is formed; a semiconductor element mounted on the element mounting land; and a semiconductor element provided between the substrate body and the semiconductor element; A wiring board, comprising: a columnar member for maintaining a predetermined gap between the semiconductor element and a resin member filled between the substrate body and the semiconductor element. 2. The wiring board according to claim 1, wherein the columnar member is made of the same kind of resin as the resin member. 3. A step of forming a columnar member on a portion other than the element mounting land of a substrate body having an element mounting land, and a step of mounting a semiconductor element on the element mounting land while supporting the columnar member. A method for manufacturing a wiring board, comprising: a step of mounting; and a step of filling a resin member between the substrate body and the semiconductor element.