JP3203346B2 - Electronic component manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device of the type in which a semiconductor component, for example, a flip chip, a BGA, a CSP, etc., is mounted on a circuit board via projecting electrodes, for example, a pump, a conductive ball (for example, a solder ball) or the like. The present invention relates to a method for manufacturing a component.

[0002]

2. Description of the Related Art In the production of the above electronic components, for example, mounting of a flip chip is performed by connecting and fixing electrodes of the flip chip and electrodes of a circuit board via bumps. Connection means are applied. A gap based on the bump is formed between the circuit board and the flip chip mounted on the board, and the gap is filled with a sealing resin for the purpose of improving the thermal cycle life.

Conventionally, such a filling of the sealing resin is performed as shown in FIG.
As schematically shown in (a) to (c), a predetermined amount of liquid sealing resin f is supplied to a gap e based on a bump d between a circuit board b and a flip chip c by applying a dispenser a. Then, the sealing resin f is separated from the gap e by utilizing the capillary phenomenon.
It was done by soaking inside. This conventional method has the following problems.

(A) It takes a considerable amount of time for the sealing resin f to penetrate into the gap e and completely fill the gap e, which is the most time-consuming step in the mounting process, and causes a reduction in production efficiency. Had become. In particular, recently, the gap e has become considerably narrower, for example, 20 to 100 μm, and the size of the flip chip c tends to be larger.

(B) The number of pumps on the lower surface of the flip chip c increases due to the high density, and the pump d prevents the sealing resin f from flowing into the gap e, so that many bubbles remain in the sealing resin f. And poor quality reliability.

(C) The viscosity of the sealing resin f is usually limited to 100 poise or less because the viscosity of the sealing resin f is difficult to fill unless the viscosity is reduced. For this reason, the content of the filler in the sealing resin f must be suppressed to, for example, 60% by weight or less, and the types of resins and curing agents that can be used are limited, and it is difficult to mix highly reliable resins.

[0007]

SUMMARY OF THE INVENTION The present inventors have applied a stencil printing means to supply the sealing resin to the gap under vacuum, and filled the gap with the supply sealing resin by vacuum. The vacuum stencil printing machine is used to fill the gap with the sealing resin, based on the idea that the problem of the above-mentioned conventional method may be solved if the suction is performed forcibly. Attempts to apply were successful as expected. However, despite the forced filling by vacuum suction,
Voids remain in the central region of the resin-filled layer, causing unfilled portions.This tendency becomes more pronounced as the size of the flip chip becomes larger and the gap becomes narrower. There was found. Incidentally, it is considered that the voids and the formation of the unfilled portion are caused by the presence of a small amount of air even though the operation is performed under vacuum, and from this viewpoint, the operation under medium and high vacuum is considered. If this is the case, the above problem may be eliminated. However, in order to enable operation under medium or high vacuum, the equipment must be pressure-resistant and not only will the equipment cost be enormous, but it will take time to return to vacuum. This is also not a preferable solution because it causes a decrease in productivity.

[0008] The present invention provides a method of manufacturing an electronic component which can manufacture a high quality and high performance product under high productivity by applying a vacuum stencil printing apparatus having a general specification (low vacuum). It was made for the purpose of providing.

[0009]

According to the present invention, after a semiconductor component is mounted on a circuit board via a protruding connection electrode, the semiconductor component is sealed in a gap defined by the protruding connection electrode between the substrate and the semiconductor component. in the method for manufacturing the electronic component of filling the sealing resin, at least one circuit board and semiconductor components, stencil in and under vacuum see extraordinary in the gap in a substantially central portion of the mounting area
Large enough to contain air remaining in the liquid sealing resin during printing
Comprising a bottom recess which is set to is come, supplies the sealing resin all around by applying the stencil printing means and under a vacuum of peripheral sides of the semiconductor components mounted on a circuit board, encapsulating By shutting off the gap from the outside air atmosphere with a sealing resin, and then returning from vacuum to substantially atmospheric pressure, a pressure difference is generated between the inside and the outside with respect to the sealing resin. while forcibly filling the sealing resin, the <br/> air slightly remaining in a substantially central portion of the mounting region by the sealing resin
The present invention relates to a method for manufacturing an electronic component, characterized in that the electronic component is sealed in the bottomed recess.

In the present invention, examples of the semiconductor component include flip-chip and other semiconductor package components such as BGA and CSP, and examples of the protruding connection electrodes include pumps and other conductive balls such as solder balls.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. According to the present embodiment, a flip chip is applied as a semiconductor component, and a bump is applied as a protruding connection electrode. FIGS. 1A to 1D are explanatory views schematically showing the steps of the production method of the present invention.
Shows the configuration of the electronic component body 1;
Comprises a circuit board 2 and a flip chip 4 mounted on the board 2 via bumps 3 in a connected and fixed state.
A gap 5 based on the bump 3 is generated between the flip chip 4 and the flip chip 4. The circuit board 2 has a bottomed recess 6 at or near the center of the mounting area of the flip chip 4.
The configuration of the electronic component body 1 is substantially the same as that of the conventional product except that the electronic component main body 1 includes the bottomed recess 6.

FIG. 1B shows the state of the process of supplying the liquid sealing resin 7 to the flip chip 4 mounted on the electronic component body 1. A stencil printing unit is applied to supply the sealing resin 7, and the sealing resin 7 supplied on the stencil 8 is supplied.
Operates the squeegee 9 to make the stencil through holes 10 and the through holes 1
It is pushed into the space 11 between the flip chip 4 and the flip chip 4 stored therein. The supply of the sealing resin 7 by the stencil printing means is performed in a casing (not shown) held in a vacuum atmosphere by operating a vacuum generator. For example, a commercially available vacuum stencil printing machine can be applied.

FIG. 1 (c) shows a situation after the sealing resin 7 has been pressed into the above-mentioned gap 11 and filled, and then the stencil 8 has been released. This is performed while the state is maintained or after the vacuum atmosphere is released. The supplied sealing resin 7 surrounds the entire periphery of the flip chip 4 in a layered manner, and blocks the gap 5 between the circuit board 2 and the flip chip 4 from the outside air.

The degree of vacuum at the time of stencil printing of the sealing resin 7 can be selected from a wide range, but it is necessary to apply a pressure-resistant vacuum stencil printing apparatus to maintain a medium or high vacuum degree. In addition to the increased load, it takes a long time to return to a vacuum, which may cause a decrease in productivity. For example, a low vacuum of 10 torr or less is sufficient.
It is maintained at a low vacuum of 1 torr, preferably about 2 to 0.1 torr. Incidentally, if the degree of vacuum exceeds 10 torr, it is not preferable because bubbles may remain in the resin.

FIG. 1 (d) shows the situation after release from the vacuum atmosphere. By releasing from the vacuum atmosphere, a pressure difference is generated between the inside and outside of the sealing resin 7 surrounding the periphery of the flip chip 4.
Is forcibly and instantaneously filled in the gap 5 between the circuit board 2 and the flip chip 4. A part of the sealing resin 7 forcibly filled in the gap 5 intrudes into the bottomed recess 6, and pursues residual air into the bottomed recess 6 with this intrusion. Serve to house the air pocket 12. Since the bottomed recess 6 serves to store the air pool 12 in this manner, even if the operation is performed under a low vacuum, voids and unfilled portions remain in the sealing resin 7 filled in the gap 5. You will not have to.

When the bottomed recess 6 is not formed on the surface of the circuit board 2, as shown in FIG. 3, voids in the sealing resin 7 filled in the gaps 5 and unfilled portions 12 remain. I do. This is because even in stencil printing in a vacuum atmosphere, a small amount of air remains, and since there is no escape for the residual air, the air gathers in the center to form an air pocket, and it is considered that voids and unfilled portions are generated.

According to the experiments of the present inventors, the gap 50 μm
m, flip chip dimensions 15 mm x 15 mm, no bottomed recess, vacuum 5 torr, diameter 0.
Although voids of 8 to 1.0 mm and unfilled portions were generated, and voids of 0.4 to 0.6 mm in diameter and unfilled portions were observed when the degree of vacuum was 1 torr, as shown in the present invention. When the bottom recess 6 is formed, residual air is stored in the recess 6, and as a result, voids and, therefore, unfilled portions do not remain in the sealing resin 7 filled in the gap 5.

According to the present invention, the supply of the liquid sealing resin by the stencil printing means is as shown in FIGS.
If it is performed also on the upper surface of the flip chip 4, FIG.
As shown in (c), overcoating with a sealing resin can be simultaneously applied.

The overcoating with the sealing resin is not always necessary, and only the filling of the sealing resin 7 into the gap 5 may be performed as shown in FIGS.
In FIG. 2, reference numeral 8 a denotes a canopy of the stencil 8 that covers the upper surface of the flip chip 4. The overcoat / stencil 8 used in FIG. 1 is not provided with such a canopy portion 8a.

In the illustrated embodiment, a flip chip 4 is used as a semiconductor component, and a bump 3 is used as a protruding connection electrode.
Is shown, but BG is used as a semiconductor component.
Even when a package component such as A or CSP is used and a conductive ball such as a solder ball is used as the protruding connection electrode, the same operation and effect as those of the illustrated embodiment can be obtained. Can be

In the present invention, the bottomed recess 6 may be formed on at least one of the circuit board 2 and the flip chip 4 (semiconductor component). The formation of the bottomed recess 6 is sufficient only on the circuit board 2 side.

The size of the bottomed recess 6 can be selected from a wide range as long as it does not hinder the formation of a circuit (not shown), but a diameter of at most about 3 mm is sufficient, and usually 0.1 mm.
It is appropriately selected and determined from a range of about 3 mm. Incidentally, if the diameter does not reach 0.1 mm, the storage space for the residual air is insufficient, which is not preferable. Further, the depth needs to be at least 0.01 mm in order to store the residual air, and in the case of the circuit board 2, it can be set to a depth substantially corresponding to the thickness of the circuit board 2 at the maximum. If the recess 6 penetrates the substrate 2, there is a possibility that the sealing resin is forcibly filled due to the pressure difference. It is necessary that the bottom side of the recess 6 be sealed. Deepen recess 6
By filling the recess 6 with the sealing resin, the reliability of the resin sealing can be further improved.

The viscosity of the liquid encapsulating resin may be from a low viscosity of about 10 poise to 1
It is possible to use a resin having a high viscosity of about 0000 poise, and a highly reliable resin compounding becomes possible. When using a sealing resin exceeding 2,000 poise, it is preferable to heat to 30 to 80 ° C. to lower the viscosity and perform the resin sealing operation.

[0024]

According to the present invention, the following effects can be obtained.

(B) After printing and sealing under vacuum, by returning to atmospheric pressure, resin sealing can be performed instantaneously.

(B) In addition to performing printing and sealing under vacuum,
Since a bottomed recess for storing residual air is formed, the gap between the semiconductor component (flip chip, BGA, CSP, etc.) and the circuit board can be sealed with resin without generating voids. Become.

(C) Because of the forced filling using the pressure difference, the viscosity of the sealing resin can be used up to about 10,000 poise, and a highly reliable resin compounding becomes possible. Resin encapsulation can be achieved.

(D) Since the operation can be performed in a low vacuum of 10 torr or less, for example, a vacuum stencil printing apparatus having a general specification can be applied, and the burden on equipment costs can be reduced.

(E) Since operation under a low vacuum is possible,
The vacuum recovery can be performed promptly, and the productivity can be improved in combination with the effect (1).

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a manufacturing method of the present invention in the order of steps.

FIG. 2 is a schematic explanatory view showing a modified example of the manufacturing method of the present invention in the order of steps.

FIG. 3 is a schematic explanatory view of a comparative example.

FIG. 4 is a schematic explanatory view of a conventional method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electronic component main body 2 circuit board 3 pump 4 flip chip 5 gap 6 recess with bottom 7 sealing resin 8 stencil 9 squeegee 10 stencil through hole 11 peripheral gap 12 air pocket

────────────────────────────────────────────────── ─── Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21 / 56,21 / 60,23 / 28

Claims (6)

(57) [Claims] An electronic component for mounting a semiconductor component on a circuit board via a protruding connection electrode and then filling a sealing resin in a gap defined by the protruding connection electrode between the substrate and the semiconductor component. in the production method, at least one circuit board and semiconductor components, remaining in the liquid sealing resin in stencil printing in and under vacuum see extraordinary in the gap in a substantially central portion of the mounting area
Lies with a bottomed recess which is set to a size capable of accommodating of the air, the sealing resin all around and under vacuum to apply the stencil printing means to the peripheral side portion of the semiconductor components mounted on the circuit board Is supplied, the gap is shut off from the outside air atmosphere by the sealing resin, and then the pressure is returned to substantially the atmospheric pressure from the vacuum, thereby generating a pressure difference between the inside and the outside with respect to the sealing resin. , while forcibly filling the sealing resin into the gap, over the air slightly remaining by the sealing resin
A method for manufacturing an electronic component, characterized in that the electronic component is driven into a substantially central portion of the mounting area and is sealed in the recess having the bottom. 2. The manufacturing method according to claim 1, wherein the circuit board has a bottomed recess, the semiconductor component has no bottomed recess, the semiconductor component is a flip chip, and the protruding connection electrode is a bump. Method. 3. The circuit board has a bottomed recess, the semiconductor component has no bottomed recess, the semiconductor component is a package component such as BGA or CSP, and the protruding connection electrode is a conductive ball. The method according to claim 1, wherein: 4. The method for manufacturing an electronic component according to claim 1, wherein the supply of the sealing resin by applying the stencil printing means is performed under a low vacuum of about 0.1 to 10 torr. . 5. A liquid sealing resin having a viscosity of 10 to 10,000.
The method for producing an electronic component according to claim 1, wherein the electronic component has zero poise. 6. The size of the recessed bottom having a diameter of 0.1 to 3.0.
The method for manufacturing an electronic component according to claim 1, wherein the thickness is at least 0.01 mm.