JPH09307015A - Integrated circuit package and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable wire bonding, without overhanging the inner top ends of leads of a lead frame and moderate the swell of the glass of a glass layer between the leads by forming a groove near and along the inner edge of the glass layer to fix the lead frame. SOLUTION: A groove 13 is formed near and along the inner edge of a glass layer 11 of a package main body 1. To adhere a lead frame 12 to the glass layer 11, the frame 21 is set on this layer and heated to melt the glass with leaving the molten glass near the groove 13 to flow thereinto. As the result, the glass layer 11 near the inner edge 12 at the groove 13 lowers than other part enough to partly moderate or prevent the swell of the glass between leads 23. The top ends of the leads 23 are placed between the groove 13 and inner edge 12 of the glass layer 11 to avoid overhang.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for integrated circuits (hereinafter also simply referred to as a package) and a method for manufacturing the same, and more particularly, to a glass seal type package such as a cerdip and a ceramic quad pack and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a glass seal type package such as a sardip or a ceramic quad pack, as shown in FIGS. 7 and 8, a package body (hereinafter also simply referred to as a body) 1 made of a ceramic substrate or the like 1
Then, the lead frame 21 is fixed as follows. That is, the lead frame 21 having a large number of leads 23 manufactured (formed) by etching (processing) a thin plate of 42 alloy (Fe-Ni alloy) or Kovar (Fe-Ni-Co alloy) is used as the main body 1 Layer formed by baking on the upper surface of the glass (hereinafter, also simply referred to as glass)
The inner tip 25 of each lead 23 is placed on the inner edge 12 of the glass layer 11 with a minute gap therebetween (see the chain double-dashed line in FIG. 8). Then, by heating and melting the glass layer 11, the lead frame 21
Each lead 23 of the glass layer 1 melted by its own weight
Then, it is fixed (fused) to the main body 1 by being solidified. Then, after mounting the electronic component S such as an integrated circuit element in the cavity 2 of the body 1 of such a package, the electrode of the electronic component S and the bonding pad portion of the upper surface 26 near the inner tip 25 of the lead 23. The (region) 28 is wire-bonded with the bonding wire B (hereinafter, also simply referred to as bonding).

By the way, when the lead 23 is fixed to the glass layer 11 in this way, the lead 23 is embedded in the molten glass layer 11 as shown in FIGS. The glass 11 between the leads 23, 23 rises relative to the upper surface 26 of the lead 23. Even if there is such a bulge M of the glass 11, conventionally, the width (thickness) LW of each lead 23 is wider than the width of a bonding tool (not shown), and therefore there is almost no effect on the wire bonding work. . And, in order to secure the fixing of the lead, it is preferable to sink it into the glass layer, and thus such a swelling is rather preferable.

[0004]

However, recently, due to the demand for finer pitch, the number of leads 23 is increased, and the width LW thereof is 0.1 to 0.2 m from the conventional 0.5 mm.
It has become remarkably thin at about m. The width LW of the lead 23 as described above is substantially equal to or smaller than the width of the bonding tool. Therefore, if there is a protrusion M of the glass 11 between the leads 23, the bonding tool interferes with the protrusion M. However, a problem has occurred such that bonding is hindered. That is, if there is such a swelling M of the glass, the bonding tool interferes with this and there is a problem that a defective bonding occurs.

To solve this problem, Japanese Patent Laid-Open No. 56-7
As in the technique described in 0650, it is conceivable to make a portion of the glass layer closer to the inner side (cavity closer portion) of the package body than a portion closer to the outer side. However, in this case, as shown in FIG. 10, the inner tip 25 of the lead 23 forming the bonding pad portion 28 is formed.
There is a shortage of glass at the side portion, the lower surface 27 does not adhere to the glass 11 and the fixation thereof is incomplete, and the tip 25 thereof is easily cantilevered (hereinafter also referred to as an overhang). If there is such imperfect adhesion or overhang, the narrow width (0.1 to 0.2 m) as described above.
However, there is a serious problem in that the lead 23 has a large deflection and bending deformation during bonding, which causes a problem in bonding. Therefore,
The technique described in the above publication cannot be applied to the fixation of leads with a fine pitch and a narrow width these days.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a glass seal type package for fixing leads with a fine pitch and a narrow width, in which the inner tips of the leads are over-covered. The purpose is to alleviate (reduce) or prevent swelling of the glass between the leads so that wire bonding can be carried out without causing a hang. Another object of the present invention is to provide a package fixed to the main body so that such leads do not shake or bend during wire bonding and the bonding tool does not interfere with the glass layer.

[0007]

In order to achieve the above object, the present invention provides a package for an integrated circuit, wherein a package body is provided with a glass layer for fixing a lead frame, wherein the glass layer has an inner edge thereof. A groove is provided in the vicinity along the inner edge. To fix the lead frame to the glass layer of the package body, the lead frame is placed on the glass layer and the glass is heated and melted. Then, of the molten glass, the glass in the vicinity of the groove flows into the groove. Due to this flow-in, the glass layer becomes lower than other portions in the vicinity of the inner edge where the groove is provided, and the swelling of the glass between the leads is partially alleviated or prevented. Since there is a gap between the groove and the inner edge of the glass layer, by positioning the inner tip of the lead within this gap, the shortage of the glass amount at the inner tip portion is reduced, and therefore It does not lead to overhang of the tip.
Thus, according to the present invention, wire bonding can be prevented without causing overhang at the inner tip of the lead.

In the above means, the distance from the inner edge of the glass layer to the groove, the cross-sectional shape and size (width and depth) of the groove are determined by the position of the bonding pad portion in the fixed lead and the width of the lead. Depending on the pitch, pitch, or the thickness of the glass layer, the swelling of the glass that hinders bonding can be eliminated, and the recessed groove can be backfilled by the molten glass flowing in from the vicinity of the recessed groove. It may be appropriately set depending on the situation.

The appropriate values are as follows.
That is, it is appropriate that the concave groove is formed at a distance (distance) of 1 to 2 mm from the inner edge of the glass layer toward the outside of the package body. In order to prevent the overhang of the inner tip of the lead, and to consider the error in the glass pace and printing, it is necessary to have an interval of about 1 mm, and if it exceeds 2 mm, the bonding pad part of the lead to be fixed This is because the distance to the groove becomes large, and the flow of the glass into the groove at the side portion of the bonding pad portion necessary to alleviate the bulge is not sufficiently secured. In this case, the groove has a width of 0.3 to 0.7 mm and a depth of 0.05.
It is preferable to set the cross-sectional shape in a substantially square shape of about 0.2 mm. Incidentally, the cross-sectional shape of the concave groove in the present invention,
The shape is not limited to a substantially rectangular shape (rectangular shape), and may be an appropriate shape such as an inverted triangular shape or an arc shape.

In the integrated circuit package according to the present invention, in which the lead frame is fixed to the glass layer of the package body, the portion near the inner tip including the bonding pad portion of each lead of the lead frame overhangs. The upper surface of the glass layer between the leads on the side of the bonding pad is present between the lower surface and the upper surface of the leads. According to this, since there is no overhang at the inner tip of the lead, even if the lead has a fine pitch and a narrow width, swaying or bending deformation does not occur at the inner tip during wire bonding. In addition, since the glass layer on the side of the bonding pad portion does not rise, the bonding tool does not interfere with the glass layer, and therefore wire bonding can be performed without any trouble.

In the method for manufacturing an integrated circuit package according to the present invention, the lead frame is placed on the glass layer formed on the package body, and the glass is melted to fix the lead frame to form the integrated circuit package. In the method for producing, a groove is formed in the vicinity of the inner edge of the glass layer along the inner edge, and when the lead frame is placed on the glass layer to melt the glass, the molten glass One of them is to let the one in the vicinity of the concave groove flow into the concave groove.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments embodying a package according to the present invention will be described in detail with reference to FIGS. In FIG. 1, reference numeral 1 denotes a substantially square plate-shaped ceramic package body (hereinafter, simply referred to as a “square”) having a cavity (concave groove) 2 having a predetermined size and a substantially square shape in a plan view in a plan view. It is also called the main body). In the present example, the main body 1 is made by firing 90% alumina by press molding. On the entire upper surface (peripheral surface) 3 except the cavity 2, glass powder is mixed with a predetermined organic binder and a solvent. Glass paste having a thickness of 0.
The glass layer 11 is formed by screen-printing a suitable number of times to a thickness of about 25 to 0.4 mm, heating this to about 400 ° C., melting and baking.

However, in the vicinity of the inner edge 12 of the glass layer 11 (the portion of the package body 1 near the cavity 2), as shown in FIGS. At a distance D1 (about 1.2 mm in this example), a concave groove 13 having a predetermined width W and a predetermined depth H and having a rectangular cross-section has a plan view on the upper surface 14 along the inner edge 12 of the glass layer 11, It is elongated and recessed. Incidentally, the design distance D2 from the inner edge 12 to the bonding pad portion (design center) 28 of the lead 23 in this example is 0.7 to
It is set to 0.8 mm. In this example, the glass layer 11 and the groove 13 are formed so that when the glass paste is screen-printed, the printed pattern is printed on the entire upper surface 3 of the main body 1 and the groove 13 is not printed. It is formed by printing using the printed pattern (mask) and baking, and the groove 13 has a substantially rectangular cross section. Further, in this example, as a result of forming the glass layer 11 on the entire upper surface 3 of the main body 1 excluding the cavity 2, the inner edge 12 of the glass layer 11 is set to coincide with the upper edge of the standing wall surface 4 of the cavity 2. ing.

In the baking step of the glass layer 11, the upper surface 14 side of the glass layer 11 easily shrinks,
As shown in the enlarged view in FIG. 1, the inner edge surface 15 has an inclined shape, and the obtuse angle portion formed by the inner edge surface 15 and the upper surface 14 is formed by the inclined portion from the inner edge 12 of the glass layer 11. , Located outside the package body 1. Although not shown in detail, the outer edge of the glass layer 11 has a substantially symmetrical cross-sectional shape with the inner edge surface 15.

Now, the glass layer 11 thus formed
The lead frame 21 is fixedly attached to the substrate as follows. First, a fine-pitch lead frame (for example, the width of the inner tip of the lead is 0.14 mm, the pitch is 0.24 mm) 21 in which the portion including the inner tie bar (not shown) is removed by punching or etching. 23 (inner lead) on the glass layer 11,
When positioned from the top, the cavity 2 is concentrically positioned and placed (see FIGS. 1 and 3). In addition, each lead 23
Of the inner edge 25 of the glass layer 11 to the outside of the package body 1 by a predetermined distance D3 (0.4 in this example).
˜0.5 mm), and is set so as to be located between the inner edge 12 of the glass layer 11 and the concave groove 13.

Then, below that, the glass layer 11 is heated at a predetermined temperature (430 to 440 ° C.) for a predetermined time (10 minutes). As a result of this heating, the lead frame 21 sinks into the molten glass 11 so as to be embedded or substantially flush with the molten glass 11 as shown in FIG. Glass rises, and the leads 23 are fixed to the solidified glass layer 11.
However, in this heating and melting process, the glass that was in the vicinity of the concave groove 13 of the molten glass flows into the concave groove 13 (shown by the chain line in FIG. 4), so that the concave groove 3 is filled while the concave groove 13 As shown in FIGS. 4 and 5, the glass layer 11 in the vicinity of the concave groove 13 including the portion where there is a protrusion and the portion near the inner edge 12 is lower than the portion where the protrusion M is present in other portions, and the protrusion between the leads 23 is increased. Alleviated or prevented.

In addition, since the inner tip 25 of the lead 23 is located between the groove 13 and the inner edge 12 of the glass layer 11 in this example, the amount of glass in the portion where the inner tip 25 is buried is insufficient. Does not occur. Furthermore, as shown in FIGS. 4 and 5, the bonding pad portion (region) of each lead 23.
The part of the inner tip 25 side including 28 is fixed so that the lower surface 27 side thereof is in close contact with the glass layer 11, and there is no overhang. The upper surface 14 of the glass layer between the leads on the side of the bonding pad portion 28 exists between the lower surface 27 and the upper surface 26 of the lead. As described above, in this example, the glass 11 is not bulged on the side of the bonding pad portion 28 without causing the overhang of the inner tip 25 of the lead 23.

The package to which the fine-pitch lead frame 21 is fixed in this way is hereinafter referred to as the main body 1.
The integrated circuit S is housed (mounted) in the die attach portion of the cavity 2, and the inner tip 2 of each electrode and each lead 23
The bonding pad portion 28 located closer to 5 is bonded by the bonding wire B, but at that time, there is no overhang of the inner tip 25 of each lead 23 and there is no interference of the bonding tool with the glass 11. Therefore, wire bonding can be performed without any problem. After that,
The lead frame 21 is sandwiched by covering the glass layer 11 of the main body 1 with a lid (not shown) on which the glass layer is formed, and under this, the glass is fused again by heating and melting. As a result, the integrated circuit is hermetically sealed to form an integrated circuit package (finished product).

Each lead 2 including the inner tie bar
When the inner tip portion of 3 is removed by punching and cutting, a flash 29 is generated at the tip as shown by the chain line in FIG. 4, but according to the present invention, this flash 29 is placed on the lower side. As a result, by disposing the lead frame 21 and melting the glass, the burr can be embedded in the glass at the time of fixing and the drop can be prevented. That is, according to the present invention, since there is no shortage of the amount of glass in the inner side portion of the package body 1 where the inner tip 25 of the lead 23 is located, that is, the inner edge 12, there is no problem in embedding the flash.

In the above description, the concave groove 13 is formed in the shape of an elongated strip one by one along the inner edge 12 of the glass layer 11, that is, along the side forming the cavity 2. , May be continuously formed so as to surround the periphery of the cavity. It may be designed in an appropriate form according to the shapes of the package and the lead frame.

Next, in the above embodiment, the distance D1 from the inner edge 12 of the glass layer 11 to the groove 13 is 1.2 mm (constant), and the width W and the depth of the groove 13 are the same. Samples in which H is changed to an appropriate size (Sample Nos. 1 to 7,
The lead 23 is fixed for each sample by making 20 pieces), and the part (bonding pad part 28) apart from the inner tip 25 of the lead 23 at that time by a predetermined distance (0.5 mm).
In the vicinity), the swelling height of the glass between all the leads 23 (range of the maximum value of the height from the upper surface 26 of the lead 23) is measured by a tracing method using a surface roughness meter, and
Overhang of the inner tip 25 of the lead 23 (lead 2
The presence or absence of a gap between the lower surface 27 of No. 3 and the glass 11) was confirmed with a magnifying glass. It should be noted that the allowable height of protrusion is +5 μm or less. The cross section of the groove 13 is substantially rectangular as described above, and the distance D3 from the inner edge 12 of the glass layer 11 to the inner tip 25 of the lead 23 is 0.4 mm.

The ceramic package body 1 used as a sample has an outer dimension of 31 mm, and an inner dimension of the cavity 2 viewed from above is 15 mm. In addition, the glass layer 11
Is formed on the entire surface of the upper surface (peripheral surface) 3 of the main body 1 excluding the cavity 2 with a thickness of 0.34 mm (the set value when the lead is fixed, 0.4 mm) excluding the concave groove 13. The lead frame 21 is made of 42 alloy (external dimensions □ 50
This is a 240 mm lead having a thickness of 0.125 mm and manufactured with an inner tie bar by etching, and a portion including the inner tie bar is cut and removed by a press. The set value of the width of each lead 23 is 0.14 mm at the inner tip 25, 0.2 mm at the outer tip (when cutting the tie bar), and the pitch is 0.24 mm at the inner tip 25 and the outer tip (when cutting the tie bar). Hour) is 0.5 mm. The results are as shown in Table 1.

[0023]

[Table 1]

Explaining Table 1, in the comparative example (Sample No. 7) in which the concave groove 13 is not provided, the glass 11 from the upper surface 26 of the lead at the measurement point (point 0.5 mm outward from the tip 25 of the lead). The rising height (range of maximum value between all leads) was +5 to +10 μm. On the contrary,
As shown in the same table, the heights of glass rising in the samples of the present invention (Sample Nos. 1 to 6) were all negative (minus). No overhang of the inner tip 25 of the lead 23 was observed in any of the samples. The allowable rising height is set for each package, but is generally +5 μm or less. The above table demonstrates that according to the present invention, an overhang does not occur, and the glass swelling between leads can be alleviated. Therefore, it is effective in eliminating the bonding failure.

As is clear from Table 1, the concave groove 13
The smaller (width, depth), the smaller the effect of alleviating or preventing the swelling of the glass on the side of the bonding pad portion 28 of the lead 23. On the other hand, the larger it is, the larger the effect of relaxing the swelling is, but on the other hand, the lead 23 is apt to be fixed (embedded) due to insufficient inflow of the molten glass into the groove 13. As mentioned above, the inner edge 12 of the glass layer 11
When the distance D1 from the groove to the groove 13 is 1 to 2 mm,
Width W is 0.3-0.7 mm, depth H is 0.05-0.2
The width W may be 0.3 to 0.5 mm, and the depth H may be 0.05 to.
It is in the range of a substantially square cross section of 0.12 mm. The larger the distance D1 from the inner edge 12 of the glass layer 11 to the recessed groove 13, the larger the bonding pad portion 28 of the lead 23.
It becomes difficult for the glass between the leads 23 corresponding to the side of the above to flow into the concave groove, and the side is not effectively lowered. Therefore, when the distance D1 is increased, it is advisable to increase the cross-sectional area while considering the flowability into the groove, that is, the backfilled state thereof.

In the above description, the package body 1 in which the glass layer 11 is formed on the entire upper surface 3 of the body 1 excluding the cavity 2, that is, the inner edge 12 of the glass layer 11 and the upper edge of the standing wall surface 4 of the cavity 2. Although the description has been given in the case of being embodied with the same ones, it goes without saying that the present invention is not limited to such a package. For example,
As shown in FIG. 6, even when the glass layer 11 is formed on the outer (outer periphery) side portion of the upper surface 3 of the main body 1 excluding the cavity 2 except the inner (inner periphery) side portion 3a. It is materialized. That is, also in this case, a concave groove 13 having a predetermined width W and a depth H should be formed in the vicinity of the inner edge 12 of the glass layer 11 along the inner edge 12 with a predetermined distance D1 from the inner edge 12. Good.

[0027]

As is apparent from the above description, according to the package of the present invention, when the lead frame is fixed to the glass layer of the package body, when the lead frame is placed on the glass layer and the glass is heated and melted, The molten glass, which was in the vicinity of the groove, flows into the groove. Therefore, the amount of this inflow makes the vicinity of the inner edge of the glass layer lower than that of other portions, so that the swelling of the glass between the leads is alleviated or prevented. Moreover,
Since the groove is provided at a distance from the inner edge of the glass layer, by locating the inner tip of the lead within this distance, there will be no shortage of the amount of glass at the inner tip portion. There is no overhang.

In addition, a portion of the lead frame near the inner tip including the bonding pad portion of each lead is fixed to the glass layer without overhanging, and the glass layer between the leads on the side of the bonding pad portion. In the package where the upper surface of the lead exists between the lower surface and the upper surface of the lead, there is no overhang at the inner tip of the lead. Since the tip does not shake or bend and the glass layer on the side of the bonding pad portion does not rise, the bonding tool does not interfere with the glass layer. Thus, according to the present invention, wire bonding can be performed without any trouble.

[Brief description of drawings]

FIG. 1 is a central longitudinal cross-sectional view of a schematic configuration of a state in which a lead frame is mounted and an enlarged view of essential parts for explaining an example of an integrated circuit package according to the present invention.

FIG. 2 is a plan view of the package body of FIG.

FIG. 3 is a plan view showing a state in which a lead frame is placed in FIG.

FIG. 4 is a view showing a state in which the glass is melted and the leads are fixed in FIG.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is an enlarged sectional view of an essential part for explaining another embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a structure in which a lead frame is fixed to a conventional glass seal type package body.

8 is an enlarged cross-sectional view of a main part of FIG.

9 is a cross-sectional view taken along the line CC in FIG. 8 for explaining the rising state of the glass layer between the leads.

FIG. 10 is a partially enlarged cross-sectional view for explaining a state in which the tip end side of the lead is overhanging.

[Explanation of symbols]

 1 Package Body 11 Glass Layer 12 Inner Edge 13 Recessed Groove 21 Lead Frame 23 Lead 25 Inner Tip 26 Lead Upper Surface 27 Lead Lower Surface 28 Lead Bonding Pad D1 Distance from Inner Edge to Recessed Groove W Concave Groove H Concave Groove depth M Glass swell

Claims (5)

[Claims] 1. A package for an integrated circuit comprising a glass layer for fixing a lead frame in a package body, wherein the glass layer has a groove near the inner edge thereof along the inner edge. A package for integrated circuits characterized by. 2. The integrated circuit according to claim 1, wherein the concave groove is formed at a distance of 1 to 2 mm from an inner edge of the glass layer to an outer side of the package body. package. 3. The groove has a width of 0.3 to 0.7 m.
3. The package for an integrated circuit according to claim 2, wherein the package has a square cross section of m and a depth of 0.05 to 0.2 mm. 4. A package for an integrated circuit, comprising a lead frame fixed to a glass layer of a package body,
An inner tip end portion including a bonding pad portion of each lead of the lead frame is fixed to the glass layer without overhanging, and the upper surface of the glass layer between the leads on the side of the bonding pad portion is A package for an integrated circuit, which is present between the lower surface and the upper surface of the lead. 5. A method for producing an integrated circuit package by placing a lead frame on a glass layer formed on a package body and fixing the lead frame to the package body by melting the glass, the glass comprising: A groove is formed near the inner edge of the layer along the inner edge, and when a lead frame is placed on this glass layer to melt the glass, the vicinity of the groove of the molten glass A method for manufacturing an integrated circuit package, characterized in that the above-mentioned one is caused to flow into the groove.