JPH0997816A - Mounting method and mounting structure of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent faulty connections together with maintaining a good connection state for a long time. SOLUTION: A semiconductor element 105 is provided with a bump electrode 107 having a plurality of pointed tails 106 at least on its one surface. On the other hand, a circuit board 101 is formed of a laminated structure having an inner layer circuit 102, and a pad 103 for mounting is formed on the board 101. A pad 103 for mounting has a recessed part and the base 110 of the recessed part is in contact with a part of the inner layercircuit 102. Further, sealing resin 109 is in advance provided on the board 101. The tail 106 is deformed by pressing the bump electrode 107 on the recessed base 110 of the pad 103 for mounting so that a contact part between the bump electrode 107 and the pad 103 for mounting may gradually expand from a point to a surface. After the tail 106 is sufficiently deformed, sealing resin 10 is cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a semiconductor device on a substrate and its mounting structure, and more particularly to a method of mounting a semiconductor device by a flip chip method on a substrate and its mounting structure.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and cost reduction of electronic equipment, the structure for mounting semiconductor elements on a substrate at high density has been simplified. A flip-chip method has been proposed as a high-density mounting structure of a semiconductor device having such a simplified structure.

The flip-chip method is a method for connecting a semiconductor element having a plurality of bump electrodes mounted on at least one surface to a circuit board with the surface facing down, and is disclosed in JP-A-4-82241. Has been done.

A conventional flip-chip mounting structure will be described with reference to FIGS. 9 (A) and 9 (B).

An insulating resin layer 2 made of a substance having an elastic recovery force such as rubber is formed on a substrate 1. Further, the mounting pad 3 is formed on the insulating resin layer 2 by the sputtering method or the vapor deposition method. The sealing resin 5 is applied to a region where the semiconductor element 4 on the insulating resin layer 2 is fixed to the substrate 1, including a region where the mounting pad 3 is formed on the substrate 1. On the other hand, a plurality of bump electrodes 6 are formed on the surface of the semiconductor element 4 on the substrate 1 side.

First, the plurality of bump electrodes 6 provided on the lower surface of the semiconductor element 4 are aligned with the mounting pads 3 on the substrate 1, and then the semiconductor element 4 is pressed and pressed onto the substrate 1. At this time, since the sealing resin 5 existing between the bump electrode 6 of the semiconductor element 4 and the mounting pad 3 on the substrate 1 is extruded, the bump electrode 6 and the mounting pad 3 are extruded.
And are electrically connected. In this conventional flip-chip mounting structure, since the insulating resin layer 2 having an elastic recovery force is formed between the substrate 1 and the mounting pad 3, the elastic recovery force of the insulating resin layer 2 and sealing The contraction force of the resin 5 stably maintains the electrical connection between the bump electrode 6 and the mounting pad 3.

[0007]

However, in this conventional flip chip mounting structure, the elastic recovery force of the insulating resin layer 2 and the contracting force of the sealing resin 5 are easily deteriorated in an accelerated test such as a temperature cycle test. As a result, the thermal expansion amount of the sealing resin 5 exceeds its contracting force and the elastic recovery force of the insulating resin layer 2, and a gap is formed between the bump electrode 6 and the mounting pad 3. Therefore, due to the gap formed between the bump electrode 6 and the mounting pad 3, the semiconductor element 4 and the substrate 1 have a poor connection.

Further, in this conventional flip chip mounting structure, the semiconductor element 4 and the substrate 1 are connected to each other with the mounting pad 3 and the insulating resin layer 2 elastically deformed. Therefore, when the balance between the contracting force of the sealing resin 5 and the elastic recovery force of the insulating resin layer 2 changes due to the temperature change, the deformation state of the mounting pad 3 also changes accordingly. As described above, due to the temperature change, a considerable amount of stress is applied to the mounting pad 3, and as a result, the mounting pad 3 may be damaged, causing disconnection or the like.

Further, in the conventional flip chip structure,
Since it is necessary to form the insulating resin layer 2 having the elastic recovery force on the substrate 1, it is inevitable that the manufacturing process is complicated and the cost is increased.

Further, in the conventional flip-lip mounting structure, since the spherical bump electrode is embedded in the sealing resin applied in advance to connect the bump electrode and the mounting pad, The sealing resin remains between the electrode and the mounting pad, and the two are connected. Therefore, there is a problem that the connection state is extremely unstable because the unnecessary sealing resin remains between the bump electrode and the mounting pad.

[0011]

In order to solve the above problems, a semiconductor device mounting method according to the present invention is a method of mounting a semiconductor device having a plurality of protruding electrodes on a substrate.
A mounting pad is formed in advance on the substrate, and a sealing resin is preliminarily provided on a region of the substrate where the semiconductor device is mounted. The protruding electrode is pressed against the mounting pad to remove the protruding electrode. The tip end is deformed so that the contact area between the bump electrode and the mounting pad is expanded from the point to the surface, and then the sealing resin is cured.

The semiconductor device mounting structure of the present invention is
The mounting pad provided on the substrate and the surface of the semiconductor device on the substrate side are pressed from the substantially spherical first portion and the mounting pad under pressure to contact the mounting pad from a point. A plurality of projecting electrodes formed to include a second portion that has been deformed so as to expand to and a sealing resin disposed between the substrate and the semiconductor device.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described in detail with reference to FIGS.

Referring to FIG. 1A, the inner layer circuit 102.
On the circuit board 101 having a laminated structure having
Mounting pad 1 having a concave shape such that the pad contacts the inner layer circuit 102
03 is provided. On the other hand, on the surface of the semiconductor element 105 on the circuit board 101 side, a plurality of bump electrodes 107 having pointed tails 106 are provided via electrodes 108.

In FIG. 1A, the sealing resin 109 is supplied onto the circuit board 101, and the semiconductor element 105 is aligned with the circuit board 101 so that the bump electrodes 107 face the mounting pads 103. ing.

Referring to FIG. 1B, the semiconductor device 10
5 is pressed against the circuit board 101, and the bump electrode 10
The tail 106 of No. 7 is embedded in the sealing resin 109. The tip of the embedded tail 106 contacts the bottom surface 110 of the mounting pad 103. Further, the semiconductor element 105 is pressed against the circuit board 101, and as shown in FIG. 1C, the tail 106 of the bump electrode 107 is plastically deformed and brought into pressure contact with the bottom surface 110 of the mounting pad 103. Then, the sealing resin 109 is used as the bump electrode 1 of the semiconductor element 105.
03 is also attached to the surface on which the sealing resin 1 is attached.
09 is cured by heating.

In the present embodiment, even if the bump electrode 107 of the semiconductor element 105 contacts the mounting pad 103 of the circuit board 101 and then the bump electrode 107 is strongly pressed against the mounting pad 103, the mounting pad 103 10
The inner layer circuit 10 formed in the lower layer in contact with the bottom surface 110
2 disperses the pressing force applied to the mounting pad 103 by the bump electrode 107. Therefore, the mounting pad 103
Is not deformed by the pressing force, and the bump electrode 1
Since only the tail 106 of 07 is plastically deformed, the bump electrode 107 can be reliably connected to the mounting pad 103 while maintaining reliability against damage to the mounting pad 103.

Further, in the present embodiment, as the characteristic of the resin for the pressure welding method, a resin having a curing shrinkage ratio larger than the thermal expansion coefficient is used as the sealing resin 109. When the semiconductor element 105 is mounted on the circuit board 101 by heating and pressurizing it at a high temperature via the sealing resin 109, the sealing resin 109 obtains a high shrinkage ratio and the bump electrode 107 and the mounting pad 103 are securely connected. You can In addition, since the curing shrinkage rate exceeds the thermal expansion rate even in a high temperature environment, the bump electrode 107
Does not act to separate the mounting pad 103 from the mounting pad 103, so that the connection state does not become unstable.

The bump electrode 10 of the semiconductor element 105 is also included.
7 has a pointed shape, the bump electrode 107 is pressed against the mounting pad 103 so that the tail 10
By deforming 6, the contact portion between the tip of the bump electrode 107 and the mounting pad 103 spreads from the point to the surface.
Therefore, the sealing resin 109 existing on the mounting pad 103 is reliably removed from the contact portion between the tail 106 and the pad 103. It is possible to obtain a reliable connection between the bump electrode 107 and the mounting pad 103 without foreign matter.

Next, a first embodiment of the present invention will be described with reference to FIG.
(A)-(D), FIG. 3 (A)-(D), FIG. 4 (A),
This will be described in more detail with reference to (B) and FIG.

FIG. 2A shows a circuit board in which a semiconductor element is not mounted. The mounting pad 103 provided on the circuit board 101 has a concave shape, and the bottom surface 110 of the concave portion is connected to the inner layer circuit 102 of the circuit board.

Now, a method of manufacturing a circuit board provided with such mounting pads will be described with reference to FIGS.

The circuit board can be manufactured by applying a method of forming a photo via hole in a so-called build-up method in which a resin layer is stacked on a printed wiring board and each layer is connected by a photo via hole.

As the circuit board 101, a laminated board in which the inner layer circuit 102 is formed on the board 111 made of a material containing epoxy is used. Referring to FIG. 3A, the inner layer circuit 102.
A photosensitive resin 112 is applied on the top. further,
As shown in FIG. 3B, the oblique light material 113 is arranged on a part of the surface of the photosensitive resin 112, and the light 114 is uniformly irradiated from above. Then, as shown in FIG. 3C, the photosensitive resin 112 in the region irradiated with the light 114 is cured on the inner layer circuit 102, while the light 114 is not irradiated only in the portion provided with the oblique light material 113. Therefore, the resin 112 is removed without being cured, and a part of the inner layer circuit 102 is exposed. Further, the mounting pad 103 is formed on the photosensitive resin 112 and the exposed inner layer circuit 102 by a plating method or the like. Finally, the surface of the mounting pad is polished.

The method of forming the circuit board 101 having the mounting pads 103 formed in a concave shape is not limited to the photo via method, and a drilling technique using laser light may be applied.

The thickness of the mounting pad 103 is not particularly limited because a desired thickness can be obtained by a known plating method, but in the present embodiment, for example, 2
It is about 0 μm. Further, the concave shape of the mounting pad 103 is not particularly limited, but in the present embodiment, a circular shape having an opening diameter of 90 μm and a bottom surface diameter of 50 μm is adopted.

Referring to FIG. 2B, the circuit board 101
An encapsulating resin 109 is formed on the region where the semiconductor element 105 is mounted.
Is supplied. As a method for supplying the sealing resin, a screen printing method can be applied, but the method is not limited to this method, and another known method, for example, the sealing resin 109 is applied to the circuit board 101 by using a dispenser. A method of supplying the above can also be applied. Further, as the sealing resin 109, an epoxy-based thermosetting type immediate curable resin having a curing shrinkage value larger than that of the thermal expansion coefficient is used. In this embodiment, for example, as the sealing resin 109, one that is cured by heating at 270 ° C. for about 30 seconds is used.

In the present embodiment, the encapsulating resin is not limited to one that is heat-curable, but a resin that is cured by irradiating ultraviolet rays can be used.

Next, as shown in FIG. 2C, the positions of the plurality of bump electrodes 107 formed on the lower surface of the semiconductor element 105 and the bottom surface 110 of the mounting pad 103 on the circuit board 101 correspond to each other. The alignment is performed as follows.

Here, the bump electrode having a tail can be formed by applying a wire bonding method as shown in FIGS. 4 (A) and 4 (B). Gold or an alloy containing gold is applied as the material of the wire for forming the bump electrode. Especially 99.999%
A material produced by adding a specific element and performing heat treatment on high-purity gold is used.

Referring to FIG. 4A, the bonding wire 115 having a spherical tip is pressed against the electrode 108 by a predetermined pressing force by the tool 116. next,
As shown in FIG. 4B, the tool 116 is applied with a predetermined force.
The bonding wire 115 is broken at a constant height by pulling it up right above the electrode 108, and the bump electrode 107 having a pointed tail with no height variation in a substantially spherical portion is provided on the electrode 108. Can be formed.

As shown in FIG. 5, the bump electrode 107 of the present embodiment has a bump diameter of 80 μm,
Tail diameter 20 μm, bump thickness 40 μm and tail length 5
0 μm. However, these sizes are not particularly limited, and for example, the bump diameter is
The tail diameter is appropriately designed according to the size of the electrode 108 provided on the semiconductor element 105, and the diameter of the bonding wire 115 used according to the desired bump diameter is substantially the same. Also, the tail length is the total bump length,
The total thickness of the bump thickness and the tail length can be designed to be 40% to 70%, but preferably 50% to 60%. If the tail length is too short or too long with respect to the entire length of the bump, the height of the bump electrode tends to vary when connecting the semiconductor element and the circuit board, and as a result, good Cannot get connection status.

Further, referring to FIG. 2D, the semiconductor element 105 is pressed and heated on the circuit board 101. Here, the amount of pressurization is set to an amount sufficient to deform the bump electrode 107, and in the present embodiment, 30 grams per one bump electrode 107. Further, the heating amount is the semiconductor element 10
The 5 side is 270 degrees, the circuit board 101 side is 80 degrees, and the holding time is 30 seconds. The amount of deformation of the bump electrode 107 is
Although it is preferable that substantially the entire tail 106 be deformed,
The height of the tail 106 after plastic deformation is at least 50% or less of the tail length before deformation.

The contact area between the tail 107 and the bottom surface 110 of the mounting pad 103 expands from a point to a surface as the plastic deformation of the tail 106 progresses. Therefore, the sealing resin 109 can be completely removed from the contact portion between the bump electrode 107 and the mounting pad 103, and the connection state can be improved. Furthermore, since the contact area is expanded, a stable connection state can be obtained.

Further, the pressing force received by the mounting pad 103 from the bump electrode 107 is dispersed in the inner layer circuit 102 arranged in the lower layer of the mounting pad 103. Therefore,
The deformation of the mounting pad 103 can be reduced.

Next, a second embodiment of the present invention will be described in detail with reference to FIGS. 6 (A)-(C) and FIGS. 7 (A)-(D).

Referring to FIG. 6A, the semiconductor device 10
5 and the plurality of bump electrodes 107 having tails 106 arranged on the semiconductor element 105 are similar to those of the first embodiment described above. Therefore, the bump electrode 107
The method shown in FIGS. 4 (A) and 4 (B) can be applied to the method of forming the above, and the shape shown in FIG. 5 can be applied to the bump electrode 107. On the other hand, the inner layer circuit 1
The circuit board 101 having a laminated structure including 02 has a bottom surface 11
A concave mounting pad 118 is provided so that 7 contacts the inner layer circuit 102. The cross-sectional shape of the recess of the mounting pad 118 is trapezoidal as shown in FIG.
The diameter of the bottom surface 117 is larger than the diameter of the opening of the recess. The method of forming the circuit board 101 provided with the mounting pad 118 having such a shape is basically the same as that shown in FIGS.
The method of forming a photo via hole of the build-up method for the printed circuit board shown in can be applied. The amount needs to be adjusted.

In this embodiment, the recess of the mounting pad 118 has an opening diameter of 40 μm and a bottom surface diameter of 50.
A circular one having a size of μm is used.

The steps of mounting the semiconductor element 105 on the circuit board 101 in this embodiment are the same as those in the first embodiment shown in FIGS. 1A to 1C and 2A to 2D. is there. However, when the semiconductor element 105 is connected to the circuit board 1
When the bump electrode 107 is plastically deformed by heating and pressurizing to 01, it is preferable that the maximum diameter of the deformed tail 106 be larger than the opening diameter of the mounting pad 118.
By doing so, the bump electrode 107 is caught in the opening portion of the mounting pad 118 and fixed inside the recess of the mounting pad 118. Therefore, the bump electrode 107
The connection holding force between the mounting pad 118 and the mounting pad 118 is
Not only the contracting force of 9 but also the physical holding force by the structural locking action is applied, so that the connection reliability can be further improved. In the present embodiment, a structural connection holding force can be obtained, and thus a sealing resin having a curing shrinkage value smaller than a thermal expansion coefficient value can also be used.

In the first and second embodiments of the present invention, an example is shown in which the mounting pads are formed in a concave shape, and a circuit board having a laminated structure having an inner layer circuit is used. However, the present invention is not limited to these.

In the third embodiment of the present invention shown in FIGS. 8A to 8C, the substrate 119 has no inner layer circuit,
The mounting pad 120 is formed on the upper surface thereof. Moreover, the mounting pad 120 is not formed in a concave shape. On the other hand, the bump electrode 1 formed on the semiconductor element 105
No. 07 has the same formation method and shape as those of the bump electrodes of the first and second embodiments of the present invention described above.

The process of mounting the semiconductor element 105 shown in FIGS. 8A to 8C on the substrate 119 is basically the same as the method shown in FIGS. 1A to 1C. is there.
In the present embodiment, since the substrate 119 does not have an inner layer circuit, it should be noted that if the pressing force of the semiconductor element 105 on the substrate 119 is excessively large, the mounting pad 120 may be deformed. On the other hand, by utilizing the plastic deformation of the bump electrode 107, the bump electrode 107 and the mounting pad 12
Since the contact area with 0 expands from the point to the surface, it is possible to prevent excess sealing resin from remaining between the bump electrode 107 and the mounting pad 120, and compared with the conventional mounting structure. , The connection state can be improved.

[0043]

As described above, according to the mounting method and mounting structure of the semiconductor device of the present invention, the tip of the bump electrode provided in the semiconductor device is provided with a pointed tail, and the tail is brought into contact with the mounting pad. The semiconductor device is pressed against the substrate so that the area is enlarged from the point to the surface as the plastic deformation of the tail progresses, and the two are connected. Therefore, the sealing resin can be completely removed from the contact portion between the bump electrode and the mounting pad, and the connection state can be improved. Furthermore, since the contact area is expanded, a stable connection state can be obtained.

Further, a substrate having a laminated structure having an inner layer circuit is used as the substrate, and the mounting pad formed on the substrate is formed into a concave shape whose bottom surface contacts the inner layer circuit. The pressing force received by the mounting pad from is dispersed in the inner layer circuit arranged below the mounting pad. Therefore, the deformation of the mounting pad can be reduced, and the connection state can be kept good.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration and a mounting process of a main part of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration and a mounting process of the first embodiment of the present invention.

FIG. 3 is a diagram showing a configuration and a forming process of a circuit board according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a step of forming a bump electrode having a tail according to the first embodiment of the present invention.

FIG. 5 is a diagram showing dimensions of bump electrodes having tails according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration and a mounting process of a main part of a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration and a mounting process of a second embodiment of the present invention.

FIG. 8 is a diagram showing a configuration and a mounting process of a third embodiment of the present invention.

FIG. 9 is a diagram showing a configuration in which a semiconductor element by a conventional flip chip method is mounted on a circuit board.

[Explanation of symbols]

 101 Circuit Board 102 Inner Layer Circuit 103 Mounting Pad 105 Semiconductor Element 106 Tail 107 Bump Electrode 108 Electrode 109 Sealing Resin 110 Bottom

Claims (10)

[Claims] 1. A semiconductor device comprising a plurality of protruding electrodes,
A method of mounting on a substrate on which mounting pads are formed, in which a sealing resin is preliminarily applied to a region where a semiconductor device on the substrate is mounted, before contacting the protruding electrodes with the mounting pads. Supply, press the protruding electrode against the mounting pad, deform the tip of the protruding electrode so that the contact area between the protruding electrode and the mounting pad expands from a point to a surface, and then seal A method for mounting a semiconductor device, which comprises curing a resin. 2. The projecting electrode comprises a substantially spherical member and a pointed member arranged at the tip of the spherical member before deformation, and the projecting electrode is pressed against the mounting pad. The method of mounting a semiconductor device according to claim 1, wherein the pointed member is deformed so as to be crushed. 3. The semiconductor device according to claim 2, wherein the pointed member is deformed to a length of at least 50% or less of a length of the pointed member before deformation. How to implement. 4. The encapsulating resin is cured by applying a predetermined amount of heat to the encapsulating resin or by irradiating the encapsulating resin with ultraviolet light. A method for mounting a semiconductor device as described above. 5. A sealing resin is pre-supplied on a region of a substrate on which a semiconductor device is mounted, before a bump electrode provided on the semiconductor device and a mounting pad formed on the substrate are brought into contact with each other. After pressing the protruding electrode against the mounting pad and deforming the tip of the protruding electrode so that the contact area between the protruding electrode and the mounting pad expands from a point to a surface, the sealing resin is applied. A mounting method of a semiconductor device to be cured, wherein the substrate is formed by a laminated structure having an inner layer member that disperses a pressing force applied from the protruding electrode to the mounting pad, wherein the mounting pad is A concave portion, a bottom surface of the concave portion being in contact with a part of the internal conductive layer, and the bump electrode being pressed against the concave portion bottom surface of the mounting pad. Semiconductor device Implementation method. 6. The size of the opening of the recess of the mounting pad is smaller than the size of the bottom of the recess, and the diameter of the tip of the bump electrode is larger than the diameter of the opening. The mounting method for a semiconductor device according to claim 5, wherein the tip is deformed until the above. 7. A structure in which a semiconductor device is mounted on a substrate, wherein a mounting pad provided on the substrate, a substantially spherical first portion provided on a surface of the semiconductor device on the substrate side, and And a second portion which is arranged at the tip of the first portion and is pressed against the mounting pad and deformed so that the contact portion with the mounting pad expands from a point to a surface. A mounting structure for a semiconductor device, comprising: a plurality of protruding electrodes; and a sealing resin disposed between the substrate and the semiconductor device. 8. The second portion has a pointed shape before deformation, and the length after deformation is at least 50% or less of the length before deformation. The semiconductor device mounting structure according to claim 7. 9. The substrate is formed by a laminated structure having a conductive layer therein, the mounting pad has a recess, and a bottom surface of the recess is in contact with a part of the internal conductive layer, 9. The mounting structure for a semiconductor device according to claim 8, wherein the protruding electrode is in contact with the bottom surface of the recess of the mounting pad. 10. The size of the opening of the recess of the mounting pad is smaller than the size of the bottom of the recess, and the diameter of the second part is larger than the diameter of the opening. 10. The mounting structure for a semiconductor device according to claim 9, wherein the mounting structure is a semiconductor device.