JP3155943B2 - Method of forming electronic component package - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity type package used for a so-called stiffener in which a recess for accommodating electronic components is formed on one side of a metal plate. The present invention relates to a package for an electronic component in which a concave portion is formed by plastic working using a resin.

[0002]

2. Description of the Related Art With the miniaturization of information devices in recent years, the packages of electronic components typified by semiconductor integrated circuits and hybrid circuits have been reduced in size and densities. Using a wiring board such as a flexible printed circuit board or the like, and connecting tens to hundreds of terminal parts formed on the wiring board to the terminal parts of the semiconductor integrated circuit by wire bonding or flip chip. Density packaging technology has been put to practical use. However, the above-mentioned wiring board has no rigidity and warpage occurs, so reinforcement is required, and a metal plate having a window frame in the center called a stiffener has been used. Further, in the above-mentioned semiconductor integrated circuit, a heat spreader is used in combination with a heat spreader to radiate heat from the package because the amount of heat generation increases with the increase in density.

Further, as a package structure, there have been proposed a structure in which each of the stiffeners and the heat spreader are bonded and bonded with an adhesive, or a radiator plate integrated type in which both are integrated with a metal plate. As the heat sink integrated type, there are a diaphragm type in which a recess for accommodating the semiconductor integrated circuit is formed by drawing a relatively thin metal plate by a drawing process, and a cavity type in which a recess is formed only on one surface of the metal plate. Roughly divided into two types. However, the cavity type is excellent in terms of sufficient rigidity and flatness, which are important characteristics required for the stiffener.

FIG. 9 shows an embodiment in which a cavity type package is manufactured by a known pressing process. That is, from one side of the metal plate 50 having a predetermined plate thickness t0, the punch 53 of the press is pressed downward as indicated by the arrow, leaving the plate thickness t1 at the bottom 52, and the metal plate 50 is pressed. The package P is formed by forming a concave portion 51 having a predetermined shape in FIG.

[0005]

However, when the above-mentioned cavity type package is formed by a well-known pressing process, the concave portion 51 having a predetermined shape is formed in the metal plate 50 by pressing with a punch 53. 51 volumes of metal are pushed into the bottom and periphery, compressing the composition of the surrounding metal parts, leaving residual stress. In addition, the surrounding metal part curls upward in the direction of the arrow. In addition, there is a serious problem that the flatness deteriorates in a state in which correction cannot be performed because the metal plate 50 is protruded from the other surface by pressing against the concave portion 51.

Further, since a large residual stress remains, the dimensions particularly in the concave portion 51 change due to a change with time, and a gap is generated between the semiconductor integrated circuit accommodated therein and peeling occurs. May cause serious quality problems. In addition, there is a problem that the desired performance as a heat spreader cannot be obtained because the thermal conductivity decreases due to a change in the metal composition. Further, in order to press the concave portion 51, a large pressing force is required, a high-output press machine is required, and the durability of the punch 53 deteriorates, and the frequency of replacing the punch 53 increases. There is also a problem that the cost is inevitably high.

On the other hand, as a method for forming a recess having a predetermined shape in a cavity type package, there is a chemical etching method. However, this etching process is not suitable for mass production because it requires a large amount of time for etching because the concave portion is formed by chemically dissolving the metal from one side of the metal plate, which inevitably increases the cost. There is a problem. Furthermore, since the melting cannot be controlled for each part in the etching process, the dimensional accuracy is deteriorated, and there is a problem that the flatness required for the package cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to form a concave portion without applying a large stress to a metal plate and satisfy various characteristics required for a package. It is an object of the present invention to provide a package for the obtained electronic component.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, an electronic component is accommodated in the concave portion of a package having a concave portion formed on one surface of a metal plate, and the metal component is accommodated in the package. What is claimed is: 1. A package for an electronic component, wherein a terminal of a wiring board disposed on one surface of a plate and a terminal of the electronic component are electrically connected, wherein the package has a shallow concave portion having a predetermined shape on one surface of the metal plate. By pressing and forming
Is approximately equal to the depth of the shallow recess on the other side of the metal plate.
Pressing step of projecting and forming a convex portion of a new height,
Only from the base end so that it is flush with the other side
Cutting step, and the recess formed by the pressing step
The other side of the metal plate
Pressing step to form a convex part again on the surface, and only this convex part
Cutting work again so that it is on the same plane as the other side
By repeating the above steps, one side of the metal plate
And the flatness of the bottom of the recess is 30
nm or less .

According to a second aspect of the present invention , there is provided a method of forming a package for an electronic component, wherein the electronic component is accommodated in the concave portion of the package having the concave portion formed on one surface of the metal plate, and is disposed on the one surface of the metal plate. A package for an electronic component in which terminals of the provided wiring board and terminals of the electronic component are electrically connected, wherein the package has a predetermined surface on one side of the metal plate.
Pressing and forming a recess with a depth of
Protruding projecting part with height almost equal to the depth of the above concave part
Formed, and only this convex portion is flush with the other surface from the tip side.
By dividing and cutting until multiple times,
While forming a recess of a predetermined depth on one surface of the metal plate,
The flatness of the bottom of the recess is set to 30 nm or less .

According to a third aspect of the present invention , there is provided a method of forming a package for an electronic component, wherein a recess having a predetermined shape shallower than the thickness of the metal plate is formed from one side of the metal plate.
On the other surface side, a similar convex part slightly smaller than the concave part is formed, and this convex part is cut by cutting to form a package.

[0012]

[0013]

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a package according to the present invention will be described in detail based on an embodiment shown in the drawings. FIG.
2 shows an example of a package for a semiconductor integrated circuit to which the package according to the present invention is applied. The package 1 is made of a metal material, has rigidity, and has a coefficient of thermal expansion matching that of a wiring board or the like, which will be described later.
Good thermal conductivity required as a heat spreader,
In addition, a copper alloy, stainless steel, or aluminum is used as a metal material that can be subjected to plastic working. A substantially rectangular concave portion 2 is formed at the center of one surface 1a side of the package 1, and a bottom portion 1c having a predetermined thickness is formed on the bottom surface of the concave portion 2 to form a cavity as a whole. .

On one surface 1a of the package 1, a wiring board 3 made of a TAB, a flexible printed board, or a normal printed board is adhered and fixed with an adhesive. A window hole 3a having substantially the same size as the recess 2 is formed in the wiring board 3, and a large number of terminal portions 4 having a line width and a pitch of about 37 nm are formed around the periphery of the window hole 3a by printed wiring. ing. Between the terminal portion 4 and an external terminal provided on an outer edge (not shown) of the wiring board 3 (not shown),
Printed wiring is applied.

Further, the chip of the semiconductor integrated circuit 5 is accommodated in the concave portion 2 formed on one surface 1a of the package 1. The semiconductor integrated circuit 5 is fixed to the bottom 1c of the recess 2 with an adhesive in a surface bonding state. What is important in this adhesive fixing is that bubbles are not formed between the semiconductor integrated circuit 5 and the bottom 1c of the concave portion 2. If the semiconductor integrated circuit 5 generates heat during operation, or if it is heated during the process of assembling the package 1 with the semiconductor integrated circuit 5 and the wiring board 3, the bubbles expand due to the heat, and the semiconductor integrated circuit 5 is separated. There is a risk that it will. For this reason, the bottom 1c of the concave portion 2 is formed with a warpage of 30 nm or less and a flatness.

On the upper surface of the semiconductor integrated circuit 5, a large number of terminals 6 having the same line width and pitch as the terminal portions 4 formed on the wiring board 3 are provided. Then, the semiconductor integrated circuit 5 and the terminal portion 4 of the wiring board 3 are electrically connected by bonding wires 7 as shown in FIG. Further, a sealing agent 8 is injected into the concave portion 2 of the package 1 to seal the semiconductor integrated circuit 5 and the bonding wire 7.

The integrated circuit component configured as described above is
In order to mount the electronic device on a circuit board (not shown), solder balls 9 are arranged on external terminals provided on the outer edge of the wiring board 3 and the electronic device is heated while being temporarily fixed at a predetermined position on the circuit board. Thereby, the solder balls 9 are melted.
Thereby, the wiring board 3 and the circuit board of the electronic device are electrically connected. On the other hand, when the semiconductor integrated circuit 5 generates heat during operation, the package 1 itself has a function as a heat spreader, so that the heat is transmitted to the package 1 and is radiated.

Next, a method of forming the concave portion 2 of the package 1 will be described with reference to FIG. FIGS. 3A to 3G show a first forming method, in which a concave portion 2 having a predetermined shape is formed by pressing one side 10a of a metal plate 10 serving as a package 1.
A method of forming a similar convex portion 11 slightly smaller than the concave portion 2 on the other surface 10b side and cutting the convex portion 11 to form the other surface 10b side flat is shown.

First, as a material of the metal plate 10 shown in FIG. 3A, a copper alloy, stainless steel, aluminum or the like is selected. FIG. 3B shows a first pressing step, in which the metal plate 10 is placed in a state where the metal plate 10 is positioned with respect to a die 12 of a press machine (not shown).
A shallow recess 2a is formed by a punch 13 mounted on the press from the side. By this pressing, the metal of the concave portion 2a moves to the other surface 10b side of the metal plate 10, and the metal plate 10
On the other surface 10b side, a convex portion 11a having a height C substantially equal to the depth of the concave portion 2a is formed so as to protrude. The outer dimension Lu of the convex portion 11a is a similar shape slightly smaller than the inner diameter dimension Ld of the concave portion 2.

When such a dimensional relationship is set, for example, even when the concave portion 2a is deeply pressed, the base end of the convex portion 11a is always kept connected without being cut from the metal plate 10. Further, it is desirable that the protruding height C of the protruding portion 11a is set to a height at which cutting can be performed with minimum stress in a cutting process described later.

FIGS. 3C and 3D show a first cutting step, in which the protrusion 11a formed on the other surface 10b side of the metal plate 10 by the first pressing step is removed by the cutter 14 on the other surface. Cut from the base end so as to be on the same plane as 10b. The cutter 14 used in the cutting step is, for example, as shown in FIG.
As shown in the figure, an arrow-shaped tooth 1 protruding from the center of the tip
4C, the cutter 14 is advanced in the direction of the arrow shown in FIG. 3C in a state where the tip of the tooth portion 14a is aligned with the center line of the convex portion 11a, and the convex portion shown in FIG. Cutting is completed by advancing to the rear end of 11a. In this cutting step, it is desirable to insert and press the pressing tool 15 into the concave portion 2a in order to prevent the bottom portion 10c from being displaced in the concave portion 2a direction by the cutter 14.

Next, FIG. 3E shows a second pressing step. In order to further deepen the primary concave portion 2a formed in the first pressing step, the first pressing step is performed by pressing the die 12. 2 is performed to form the concave portion 2 having a completed depth. As a result, the first surface is placed on the other surface 10b side of the metal plate 10.
A projection 11 having a height substantially equal to the depth of the recess 2 is formed in the same manner as described below. The outer dimensions of the convex portion 11 are also similar to the inner diameter of the concave portion 2 and are slightly smaller.

Thereafter, the second cutting shown in FIG. 3 (F) is performed. That is, similarly to the first cutting step, the convex portion 11 formed on the other surface 10b side of the metal plate 10 in the second step is cut from the base end by the cutter 14 so as to be flush with the other surface 10b. I do. The cutter 14 used at this time is the same as that used in the first cutting step. Then, the cutter 1 is moved in the direction indicated by the arrow shown in FIG.
4 is advanced to the rear end of the protruding portion 11 to obtain FIG.
As shown in (1), the convex portion 11 is cut, and the other surface 10b side is formed flat to form the package 1. A relatively thin bottom 1c having a predetermined plate thickness is formed on the bottom surface of the recess 2.

The above-described forming method is suitable for preventing residual stress and stress beforehand because the metal plate 10 is pressed to such an extent that no stress is applied and is gradually cut. The warpage and flatness of 30 nm or less required for the bottom 1c of the second 2 are obtained, and
The warpage and flatness of 70 nm or less required for the entire package 1 can be obtained. Furthermore, even when the thickness of the bottom portion 1c located on the bottom surface of the concave portion 2 is reduced, the bottom portion 1c is not likely to be damaged because the tensile force by cutting is small. Further, since the pressing force in each pressing step can be reduced, there is a feature that processing can be performed even with a small press machine.

In the method illustrated in FIG. 3, one concave portion 2 is formed in one metal plate 10, but one concave portion 2 is formed in one wide metal plate. A plurality of recesses of about 2 to 5 may be formed simultaneously. Further, the concave portion may be a circle or a polygon other than a square.

Further, in forming the concave portion 2, the convex portion 11 may have a tapered shape from the base end to the tip end of the metal plate 10 as shown in FIG. By forming the tapered portion 11b, it may be formed in a substantially trapezoidal shape. In addition, other than the tapered shape, it may be formed in a rounded R shape.

[Other Embodiments] FIG. 4 shows a second method of forming the recess 2 of the package 1.
The forming method shown in FIG. 4 is a modified example of the forming method shown in FIG. 3, in which the concave portion 2 is pressed and formed by one pressing step, and the convex portion 11 is formed. Thus, the convex portion 11 is cut to form a cavity-type package 1.

First, the concave portion 2 is formed in the center of the metal plate 10 by a single pressing step. By this pressing,
On the other surface 10 b side of the metal plate 10, a convex portion 11 having substantially the same height as the depth of the concave portion 2 is formed so as to protrude. Next, in the first cutting step, the thickness of the line A shown in FIG. This thickness is reduced by the metal plate 10 by cutting.
Is set to a size that does not give stress to

Further, in the second cutting step, the cutter 14 shown in FIG.
Cut to line thickness. Then, in a third cutting step, the cavity type package 1 is finally formed by cutting to the thickness of the C line shown in FIG. 4 and flattening the other surface 10b side of the metal plate 10. According to this forming method, since the concave portion 2 is formed by pressing in one pressing step, the process is simplified and the efficiency is improved. Further, since the cutting is divided into a plurality of times, the residual stress and the stress on the metal plate 10 are reduced, and the feature of obtaining a desired flatness is the same as that of the above-described second forming method.

In the above embodiment, if the metal plate 10 is thin or the recess 2 is relatively shallow, each step may be performed once. Furthermore, FIG.
As shown in (2), the shape of the concave portion 2 may be changed to a multi-stage type in which the depth gradually increases toward the center, or the concave portion 2 may be formed in a substantially mortar shape. Thus, the recess 2
Can be set to any other shape.

FIGS. 5A to 5D show a third method of forming the concave portion 2 of the package 1. FIG. In the example shown in FIG. 5, a predetermined-shaped concave portion 2 is pressed from one surface 10a of the metal plate 10, and a number of columnar convex portions are formed to project from the other surface 10b side. 2 shows a method of cutting by the following method.

FIG. 5A shows a pressing step, in which a metal plate 1 placed in a positioning state on a die 16 of a press machine (not shown).
The concave portion 2 is formed by pressing the concave portion 2 from the one surface 10a side with a punch 17 mounted on the illustrated press machine. Die 1 above
6 has a plurality of grooves 16a at positions corresponding to the lower portions of the concave portions 2.
When the concave portion 2 is formed by the punch 17, the metal approximately equal in volume to the concave portion 2 moves to the plurality of grooves 16 a, and the other surface 10 b of the metal plate 10 as shown in FIG.
A large number of columnar projections 18 (corresponding to the projections) are formed to project from the side.

In the formation method illustrated in FIG.
In addition to the columnar projections 18, a large number of columnar projections 19 as shown in FIG. 6 (B) or irregular shapes shown in FIG. 6 (C) so that they can be easily cut in a later cutting step. Convex part 20 of
You can also Further, in addition to a columnar shape, it may be a prismatic shape, and an appropriate shape can be selected according to conditions of a material, a cutter, and the like.

FIG. 5C shows a cutting process, in which the metal plate 10
Many columnar projections 18 formed on the other surface 10b side of the
Is cut from the base end by the cutter 14 so as to be flush with the other surface 10b. At this time, as shown in FIG. 6, the cutter 14 is parallel to the longitudinal direction of the columnar projection 18 and aligned with the center line of the columnar projection 18 in the direction indicated by the arrow shown in FIG. 5 and by advancing to the rear end of the columnar projection 18, FIG.
As shown in (C), the other surface 10b is formed flat. Also in this cutting step, the inside of the concave portion 2 is pressed by the pressing tool 15 in order to prevent the displacement of the bottom 1c.

Through the above steps, the concave portion 2 is formed on the one surface 1a side of the package 1, and the bottom portion 1c having a predetermined thickness is formed on the bottom surface of the concave portion 2. In the forming method shown in FIG. 5, since a large number of columnar projections 18 are cut, the area to be cut by the cutter 14 is reduced, and the columnar projections 18 can be cut with a small force. Therefore, the residual stress and the stress on the package 1 can be reduced. Furthermore, since the force for pressing the columnar projections 18 may be small, processing can be performed even with a small press machine.

In the embodiment described above, a cutter having a tooth portion is used as a cutting step, but cutting may be performed by milling or a grinder. Although a semiconductor integrated circuit is illustrated as an electronic component housed in the recess of the package, other electronic components such as a hybrid circuit, an inductor chip, or a register array may be used. The present invention is not limited to these embodiments, but can be variously modified without departing from the present invention.

As described above, according to the method for forming an electronic component package of the present invention, a shallow concave portion is formed by pressing one surface of a metal plate, and a convex portion having a height substantially equal to the depth of the shallow concave portion is formed on the other surface. After the pressing step of projecting and forming the portion, and the cutting step of cutting only the convex portion so as to be flush with the other surface, the concave portion formed by the pressing step is pressed further deeper to the other surface to form the concave portion again. The pressing step of forming the protrusions and the cutting step of cutting the protrusions again so that only the protrusions are flush with the other surface are repeated to form the recesses, thereby minimizing stress during processing and deforming. Can be prevented, and the flatness at the bottom of the concave portion required as a package can be formed with high precision of 30 nm or less. Further, a concave portion having a predetermined depth is formed on one surface of the metal plate by pressing, and a convex portion having a height substantially equal to the depth of the concave portion is formed on the other surface side, and only this convex portion is formed on the other surface. Since the cutting is performed by dividing into a plurality of times until the same surface is obtained, the stress at the time of processing can be minimized and deformation can be prevented, and the flatness at the bottom of the concave portion required as a package is set to 30 nm or less. It can be formed with high precision. Further, since the metal of the concave portion is transferred to the other surface side to form the convex portion, even a pressing machine with a small pressing force can be easily formed, the service life of the punch and the like can be extended, and the convex portion cutting can be performed. Since the life of the cutting tool for performing the cutting can be extended, the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an electronic component package according to the present invention.

FIG. 2 is a cross-sectional view showing an electronic component package according to the present invention.

FIGS. 3A to 3G are process explanatory views showing a first package forming method of the present invention. FIGS.

FIG. 4 is a sectional view showing a second package forming method of the present invention.

FIG. 5 is a process explanatory view showing a third package forming method of the present invention.

FIGS. 6A to 6C are plan views showing modified examples of a projection formed on a metal plate.

FIG. 7 is a cross-sectional view showing a modified example of a projection formed on a metal plate.

FIG. 8 is a cross-sectional view showing a modified example of a recess formed in a metal plate.

FIG. 9 is a cross-sectional view showing a conventional method for forming a concave portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package 1a One surface 1b Multi-sided surface 2 Concave part 3 Wiring board 4 Terminal part 5 Semiconductor integrated circuit 6 Terminal 10 Metal plate 11 Convex part

Claims (3)

(57) [Claims] An electronic component is accommodated in a concave portion of a package having a concave portion formed on one surface of a metal plate, and a terminal of a wiring board disposed on one surface of the metal plate and a terminal of the electronic component are connected to each other. An electronic component package electrically connected to the metal plate, wherein the package is formed by pressing a shallow recess having a predetermined shape on one surface of the metal plate.
On the other surface side, a convex part having a height almost equal to the depth of the shallow concave part
A pressing step of projecting and forming only the convex portion on the other surface
Cutting process to cut from the base end so that it is on the same plane as
And press the recess formed by the pressing step further deeply.
The convex portion is formed again on the other surface of the metal plate by pressing.
And a pressing step of protruding and forming only this convex portion with the other surface.
Repeat the cutting process to cut again to make one side
In this way, a recess with a predetermined depth is formed on one side of the metal plate.
And the flatness of the bottom of the recess is 30 nm or less.
A method for forming an electronic component package. 2. A package having a concave portion formed on one surface of a metal plate for housing an electronic component in the concave portion, and a terminal of a wiring board disposed on one surface of the metal plate and a terminal of the electronic component. An electronic component package electrically connected, wherein the package has a predetermined surface on one surface of the metal plate.
At the same time as forming a recess of depth, the other side of the metal plate
A protrusion with a height almost equal to the depth of the above recess is projected on the surface side
And only this convex portion is flush with the other surface from the tip side.
By dividing into multiple cuts until it becomes
A recess having a predetermined depth is formed on one surface of the metal plate,
A method for forming a package for an electronic component, wherein the flatness of the bottom of the part is 30 nm or less . 3. A press-formed recess having a predetermined shape smaller than the thickness of the metal plate from one side of the metal plate, and a similar protrusion slightly smaller than the recess formed on the other side. 3. The method for forming a package for an electronic component according to claim 1, wherein the package is formed by cutting the convex portion by a cutting process.