JPH11274191A - Apparatus for encapsulating semiconductor element with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten forming cycle and ensure high quality and high productivity by reducing a wire sweep WSP and improving the charging rate of a resin. SOLUTION: A gate 118 for encapsulating with a resin 106 into a cavity 112 is formed near two adjacent corners of the cavity 112, the encapsulating direction of the resin 106 into the cavity 112 from the gate 118 is directed toward the center of a substrate 102 to enable the resin encapsulating apparatus of a semiconductor element with high quality and high productivity. This greatly improves the charging rate (T/F speed) of the resin 106 and improves the reduction of the wire sweep WSP at the same time, thereby providing superior effect of reducing the mean cycle owing to the improved the product quality and high speed charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transfer molding a ball grid array integrated circuit, a bonding wire, and the like, for example, by sealing a resin from a gate in a cavity containing an integrated circuit or the like on a semiconductor device substrate. The present invention relates to a resin sealing device for a semiconductor element to be sealed by a sealing method.

[0002]

2. Description of the Related Art Generally, when an integrated circuit or the like of a semiconductor element provided on a substrate is sealed with a resin, a resin sealing method by transfer molding is often used. In the case of this transfer molding, a substrate on which an integrated circuit and the like are disposed is set in a mold, and the plasticized resin contained in a vertically formed cylindrical pot is pushed upward by a plunger to move in a horizontal direction. Resin sealing is performed by filling the inside of the sealing cavity through a runner disposed in the sealing cavity.

FIG. 6 shows a partial cross section of a ball grid array BGA in a semi-finished product state as an example.

An integrated circuit 4 is fixed on the substrate 2, and the integrated circuit 4 and the surface 2 a of the substrate 2 are bonded to bonding wires 8.
Are joined by The front surface 2a of the substrate 2 is connected to the back surface 2b of the substrate 2 via the via hole 10, and the terminal of each circuit on the back surface 2b of the substrate 2 is connected to a hemispherical solder 14 arranged in an array. Connection with an external circuit is made via the hemispherical solder 14. In recent years, the demand for this type of ball grid array BGA has been rapidly increasing because the connection with an external circuit can be realized only by press contact.

As shown in FIG. 6, the integrated circuit 4 and the bonding wires 8 on the substrate 2 or the surface 2a of the substrate 2
In order to protect this, the cavity 12 is sealed with a thermosetting resin 6. This sealing is realized by the transfer molding described above.

The resin sealing method as shown in FIG. 6 is called a side gate method since the gate 18 is located on the side surface of the resin 6 and the resin is sealed from the lateral direction.

In addition, for example, in Japanese Utility Model Laid-Open No. 4-50216, as shown in FIG. 7, a lead frame 3 is provided to protect an integrated circuit 24 fixed on a substrate 22.
Gates 38a and 38b are formed at positions slightly shifted in the horizontal direction, one at a time, for each of the cavities 32 divided into upper and lower portions by the boundary between the gate 3 and the bonding wire 28.
A sealing device for sealing a resin into the cavity 32 has been proposed from 8a and 38b.

[0008]

However, in the conventional resin sealing device described above, the bonding wire 8 is bent by the flow of the resin 6 when the resin 6 is filled. Sweep WS
There is a problem that P is easily deteriorated.

Here, a description will be given of the wire sweep WSP.

FIG. 8A is a plan view showing the integrated circuit 4 and the bonding wires 8 before the resin 6 is filled. As shown in FIG. 8A, before the resin 6 is filled, the integrated circuit 4 is linearly connected between the via holes 10 by the bonding wires 8 and fixed. However, when the resin 6 is poured in the direction indicated by the arrow R in FIG. 8B, the bonding wire 8 may be bent by the force of the resin 6. FIG. 8 (c) shows one bonding wire 8 taken out as a sample in such a case (bent state).

The broken line in FIG. 8C shows the bonding wire 8 before the resin 6 is filled, and the solid line shows the bonding wire 8 after the resin 6 is filled. The length of the bonding wire 8 is l, and the length from the position of the broken line before filling to the maximum point P from the solid line after filling is x
Then, the wire sweep WSP is obtained as in the following equation.

Wire sweep WSP = x / l × 100% (1)

The value (the value of the wire sweep WSP) obtained by the equation (1) is used as one of the criteria for judging the quality of the product.

As described above, in the related art, the resin 6 is injected into the cavity 32 divided into two parts vertically by a side gate method or as shown in FIG. When filled, the angle θ between the direction in which the bonding wire 8 (108) is stretched and the flow direction R of the resin 6 is particularly large near the corner of the integrated circuit 4, as shown in FIGS. 2A and 2B described later. (9
(Close to 0 °), the value of the wire sweep became large.

For this reason, the fact is that the filling speed of the resin 6 must be reduced. That is, if the speed is increased without controlling the filling speed, the wire sweep W
This is because not only is the SP increased, but also air is trapped in the corners of the integrated circuit 4 and voids and unfilled portions are liable to occur.

Incidentally, the following three factors can be considered as factors affecting the wire sweep WSP.

(1) Length, thickness, and tension (shape, density, uniformity) of bonding wire 8 (2) Performance (viscosity, reaction speed) of resin 6 (3) Mold design and molding conditions

The above (1) depends on the package design and is determined. The degree of freedom is relatively small, and it is difficult to reduce the wire sweep WSP.

With respect to the above (2), the quality of the viscosity of the resin 6 is determined by comprehensive quality evaluation, and changing the viscosity (reducing the viscosity) requires much labor for re-evaluation of reliability. It is. Also, for example, even if a low-viscosity resin is used,
It takes time to cure (solidify). On the other hand, the curing reaction of the fast-cured resin progresses during filling, and the wire sweep W
Since the SP tends to increase, the degree of freedom is also small similarly to (1).

Regarding the above (3), it has conventionally been considered that a good result can be obtained relatively easily by finding the optimum value of the filling time if the air vent and the gate position are appropriately designed.

For this reason, conventionally, the filling speed of the resin 6 is controlled in multiple stages, and particularly, the flow rate is controlled in an area where the wire sweep WSP is easily deteriorated. However, although this method contributes to the reduction of the wire sweep WSP, it cannot contribute to the improvement of the manufacturing cycle.

Further, a method of increasing the number of air vents or improving the flow of the resin 6 by vacuum molding has been devised, but this method is effective in suppressing voids,
There is little effect in reducing the wire sweep WSP. There is also a method of adjusting the temperature of the mold and the filling timing to match the reaction speed of the resin 6, but in this method, although the wire sweep WSP is reduced, it is difficult to improve the filling speed.

The present invention has been made in view of such a problem, and realizes high quality and high productivity by reducing the wire sweep WSP and shortening the resin filling time. It is an object of the present invention to provide a resin sealing device for a semiconductor element that can be used.

[0024]

According to the present invention, a resin is sealed from a gate into a cavity for accommodating an integrated circuit or the like on a substrate of a semiconductor element, and the resin sealing of the semiconductor element for sealing the integrated circuit or the like is performed. In the apparatus, the gate for sealing the resin in the cavity is formed near two adjacent corners of the cavity, and the direction of sealing the resin from the gate into the cavity is set at the center of the substrate. Thus, the above problem has been solved.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 5 is a schematic sectional view of a resin mold for a ball grit array to which the present invention is applied.

In FIG. 5, a mold 130 is provided with an upper mold 132.
And the lower mold 134. A carrier plate 136 is provided on the lower mold 134 to hold down the end 102a of the substrate 102 of the ball grit array BGA placed on the lower mold 134. Then, the runner 138 passes above the carrier plate 136. Further, an integrated circuit 104 is fixed on the substrate 102, and the integrated circuit 104 and the surface 102 a of the substrate 102 are connected by a bonding wire (gold wire) 108. The connection of the bonding wires 108 is the same as that of the related art shown in FIG.

In the vertically formed pot 140,
The pot 140 contains the plasticized resin 106.
Is provided with a plunger 142 for pushing up the resin 106 upward. This plunger 142
The resin 106 pushed up by the runner (Cal 1) is disposed horizontally above the carrier plate 136.
44) ball grit array BG via 138
A is sealed from the gate 118 in the sealing cavity 112 of FIG.

FIG. 4 is a plan view showing a state where the bonding wires 108 are bonded to the integrated circuit 104 fixed on the substrate 102.

As shown in FIG. 4, the corners of the integrated circuit 104 are referred to as zones 1 to 4, respectively. Of these, for two adjacent zones (zones 1 and 4 in this embodiment),
The gate 118 is formed so that the resin 106 is filled in a direction indicated by an arrow, that is, a direction toward the center of the substrate 102.

The bonding wire 108 is connected to the integrated circuit 10.
4 are connected more stably, and the interval between the external connection ends of each bonding wire 108 (see FIG. 6).
In order to ensure a large space between the solders 14, the closer to the corner, the more diagonally the outer peripheral side of the integrated circuit 104 is connected. Further, when the resin 106 is poured, the integrated circuit 10
At the corner No. 4, the bonding by the bonding wire 108 is not performed. These are exactly the same as the conventional ones.

In this embodiment, attention is paid to this fact, and the gate 118 having the above-described configuration is formed. In addition, in order to confirm the operation and effect of the gate 118 according to this configuration, the substrate 102 is filled with the resin 106. When the gate 11
A comparative test was performed by changing the position of No. 8, the size of the gate 118, the filling speed (T / F speed) of the resin 106, and the like. In addition, as shown in FIG. 4, each corner of the substrate 102 is defined as zones 1 to 4.

First, for comparison with the structure according to the present embodiment, test Nos. Tests were performed using the conventional filling method as Nos. 1 to 5.

In this test, two types of gate sizes, “large” and “small”, were prepared, and the filling speed (T / F speed) of the resin 106 was set to “low”, “medium”, The test was performed in four stages of "Slightly high speed" and "High speed".

Test No. 1 corresponds to FIGS. 2 (a) and 3
As shown in (a), the gate position is set at the center of the corner and the corner (zone 1 and zone 4), the gate size is made large, and the filling speed (T / F speed) of the resin 106 is made low. In the one-point gate method.

The mold temperature (mold temperature) is set to a uniform temperature in order to make the same conditions in all tests.

Test No. 2 is the test No. 2 with the same (large) gate size and T / F speed as in FIG.
As shown in (b), the gate position is set only at the corner (zone 4), and the gate system is based on one corner.

Test No. No. 3 is the test No. 2, the gate position and the T / F speed were the same, and only the gate size was changed to a smaller size.

Test No. No. 4 is a test No. 2, the gate position and gate size were the same, only the T / F speed was changed from low to medium, and the T / F speed was slightly increased.

Test No. No. 5 is the test No. 3 and the gate size are the same, and the T / F speed is test N
o. In this state, the speed is set to the medium speed while maintaining the same condition as in the case of FIG.

On the other hand, test No. Nos. 6 to 8 relate to the present embodiment, in which the gate 118 is formed near two corners of two adjacent places (zones 1 and 4) of the cavity 112, and the resin 106 from the gate 118 into the cavity 112 is formed. Is directed toward the center of the substrate 102.

Test No. In Nos. 6 to 8, two small gate sizes are selected, and only the T / F speed is changed in three stages of low speed, slightly high speed, and high speed, respectively.

FIG. 3B shows the test results. Note that the remarks in FIG. A comparison with 1 is shown.

First, the test No. Let's start with 1.

It should be noted that the wire sweep WSP is shown in five stages of "bad", "slightly bad", "medium", "good", and "best" based on the numerical values of the data obtained from the test results. I do.

Test No. As shown in FIG. 2A, a gate 118 is provided at the center of the zones 1 and 4 to fill the resin 106, so that the zones 1 and 4 and the zones 2 and 3 are similar to each other. Wire sweep WS
The state of P is shown. However, the integrated circuit 104
Since the resin 106 protrudes, the resin 106 flows around the integrated circuit 104 so as to avoid the integrated circuit 104. Therefore, the intersection angle between the flow direction (progressing direction) R of the resin 106 and the bonding wire 108 (hereinafter simply referred to as the intersection angle) ) Results in bad results especially in zones 2 and 3.

Next, test No. In FIG. 2, as shown in FIG. 2B, the resin 106 is filled from the corner zone 4 of the integrated circuit 104. As described above, at the corners of the integrated circuit 104, the bonding wires 108
And the flow direction of the resin 106 almost coincides (the intersection angle θ is small), so that in the zones 2, 4, and especially 4, the wire sweep WSP has a very good result.

On the other hand, in the zones 1 and 3, the crossing angle θ is almost 90 °, so that the zones are most easily affected. Therefore, in zones 1 and 3, the test No. Compared to No. 1, the wire sweep WSP has a bad result.

Next, the test No. No. 3 is the test No. 2
No. only the gate size under the conditions of test No. This is a case where the gate is changed to a small-sized gate which is about half the opening of the gates 1 and 2. Since the T / F speed remains constant, the flow rate of the resin 106 hardly changes. 3
Then, in the test No. There is no significant difference when compared with 2.

Test No. In Test No. 4, the gate size was changed to Test No. Return to the same size (large) as 1, 2 and T /
Only F-speed is increased from low speed to medium speed.

Test No. 2 also becomes the state shown in FIG. 2 (b), and in zone 4 near the gate entrance, the test N
o. Even if the filling speed of the resin 106 is higher than that of No. 2,
Since the intersection angle θ is small, a relatively good result is shown. However, since the intersection angle θ is large in the zones 1 and 3, the test N
o. This is a bad result compared to 1.

Test No. In Test No. 5, the gate size was changed to Test No. A gate whose opening is smaller than that of the gate of No. 4 by about half was adopted (same as test No. 3), and the T / F speed was no. The test was performed at the same medium speed as in No. 4.
Therefore, the flow rate of the resin 106 hardly changes. In Test No. 5, Test No. There is no significant difference when compared with 4.

As a result, test No. 1 in which the resin 106 is filled from one corner (zone 4). In 2-5, zone 3
Since the intersection angle θ is considerably large (close to 90 °) between and the zone 1, it can be seen that the wire sweep WSP has not been improved.

Next, gates 118 are installed at two locations (two adjacent locations of the cavity 112) of zone 1 and zone 4, which are the features of the present invention, and the direction of filling the resin 106 into the cavity 112 from the gate 118. And test No. in the case where the test pieces are directed to the center of the substrate 102. 6 ~
Consider No. 8.

Test No. No. 6 is a test No. Based on condition 3, the position of the gate 118 is filled with the resin 106 from two locations, zone 1 and zone 4. As shown in FIG. 2C, the wire sweep WSP is not improved because the intersection angle θ increases in the zones 2 and 3.

Test No. In Test No. 7, When the T / F speed is increased from low to slightly high compared to 6,
Test No. Good results were obtained as compared with No. 6.

Test No. In No. 8, the T / F speed is further increased from slightly high speed to high speed. As a result, test N
o. Clearly better results are obtained compared to 6 and 7.

This is because, as shown in FIG. 1, by increasing the T / F speed, the intersection angle θ between the filling direction of the resin 106 and the bonding wire 108 becomes “small”, and the resin 106 of the bonding wire 108 becomes smaller. This is probably because the force received from the vehicle has decreased.

That is, in this embodiment, two gates are provided for the same cavity 112, and the conventional T / F speed is set so that the angle θ between the bonding wire 108 and the filling direction of the resin 106 becomes “small”. (For example, increase the T / F speed from the conventional low speed to high speed)
It can be seen that the best result is obtained by doing so.

The filling speed is described as “high speed”, “slightly high speed”, “medium speed”, “low speed” as described above.
The specific speed differs depending on the mold temperature, the gate size, and the type of the resin 106 (particularly, the viscosity and the curing speed), and is relatively “low” or “high” from the reference T / F speed (medium speed). And naturally, the standard T /
If the F-speed changes, the way of expression will change.

That is, as shown in FIG.
In the vicinity of other corners (zones 2 and 3) other than the two gates (zones 1 and 4) to be filled, the filling speed and the intersection angle θ of the bonding wire 108 with the flow direction of the resin 106 become “small”. What is necessary is just to set it.

[0062]

As described above, according to the present invention, the filling speed (T / F speed) of the resin 106 is greatly improved, and the reduction of the wire sweep WSP is simultaneously improved. And the average cycle can be shortened by high-speed filling.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a resin sealing device for a semiconductor element according to the present invention.

FIG. 2 is a plan view showing a main part when a test is performed in a resin sealing device for a semiconductor element according to the present embodiment as in FIG. 1;

FIG. 3 is a diagram showing molding conditions and results thereof in performing a test of the present embodiment.

FIG. 4 is a simplified plan view of a resin sealing device for a semiconductor element according to the present invention.

FIG. 5 is a sectional view of a resin sealing device for a semiconductor element according to the present invention.

FIG. 6 is a sectional view showing an example of the related art.

FIG. 7 is a sectional view showing an example of the related art.

FIG. 8 is a diagram illustrating a wire sweep.

[Explanation of symbols]

 102: substrate 104: semiconductor element 106: resin 108: bonding wire 112: cavity 118: gate WSP: wire sweep

Claims (1)

[Claims] 1. A semiconductor device resin sealing device for sealing a resin from a gate into a cavity containing an integrated circuit or the like on a substrate of a semiconductor device and sealing the integrated circuit or the like. The gate for enclosing the cavity is formed near two adjacent corners of the cavity, and the direction of encapsulation of the resin from the gate into the cavity is directed to the center of the substrate. Resin sealing device for semiconductor elements.