JPH039539A - Metal mold for semiconductor resin sealing - Google Patents

Abstract

PURPOSE:To reduce the amount of resin flowing and passing the same wire bonding region, by forming and arranging a plurality of resin injection gates at symmetrical positions in a cavity part. CONSTITUTION:A semiconductor integrated circuit element mounted on a lead frame is wire-bonded and then resin-sealed by using a pair of an upper and a lower metal molds 1a, 1b. Resin injection gates 3a, 3b for cavities 2a, 2b are arranged at symmetrical positions with respect to the centers of the cavities 2a, 2b. The one 3a of the resin injection gates is formed in the top force 1a, and the other one 3b is formed in the bottom force 1b. By this constitution, the amount of resin passing the same wire bonding region at the time of resin sealing is reduced, so the deformation of wire can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for sealing a semiconductor integrated circuit element (hereinafter referred to as IC) with a resin.

[Conventional technology]

Conventionally, this type of mold for semiconductor resin encapsulation has been provided with one resin injection gate (hereinafter referred to as gate) for each cavity formed by the upper and lower molds.

In addition, there is a ventilation groove (hereinafter referred to as an air vent) for discharging the air sealed in the cavity space along with resin injection.
was provided at a location other than the gate section.

[Problem to be solved by the invention]

Since the conventional semiconductor resin sealing mold described above has one gate for one cavity, all the resin forming the package flows into the cavity through the one gate.

Therefore, the resin that first flows into the cavity first passes over the wire bonded to the gate side, then passes over the wire on the opposite side to the gate, and finally flows to the end face of the cavity on the opposite side to the gate. do. During this time, resin sequentially flows in from the gate, and the cavity portion is finally filled with resin via the above-mentioned path.

In this case, the wire bonding region on the gate side has a larger amount of resin passed through during resin encapsulation than the wire bonding region on the opposite side to the gate, so the amount of deformation of the wire becomes larger. Then, if the distance between the bonded wires is narrow or the length of the wire is long, short-circuit defects or open defects due to deformation occur, which causes a decrease in yield.

[Means to solve the problem]

The present invention provides a pair of upper and lower semiconductor resin molding molds for resin-sealing a semiconductor integrated circuit element mounted on a lead frame after wire bonding, in which a resin injection gate into a cavity is located at the center of the cavity. At least one set of the resin injection gates is arranged symmetrically with respect to each other, and one of the resin injection gates is formed in the upper mold, and the other is formed in the lower mold.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view showing the vicinity of a mold cavity in a first embodiment of the present invention. Hereinafter, the suffix a in the symbols indicates a stopper die, and the suffix b indicates a lower die.

As shown in the figure, la and Ib are bases, 2a and 2b are cavities, 3a and 3b are gates, 4a and 4b are sub-runners, and 5a and 5b are air vents.

In this embodiment, a gate 3a is formed at one corner of the upper mold cavity 2a, and air vents 5a are formed at each of the corner and two adjacent corners.

Further, regarding the lower mold, a gate 3b is formed at a part of the corner symmetrical to the center of the cavity with respect to the position where the gate 3a is formed in the upper mold. The air vent 5b is provided at a position corresponding to the upper mold.

Therefore, the same number of gates are always formed on the upper mold and the lower mold. Further, by forming the upper gate and the lower gate in one cavity, it is possible to prevent the IC mounting portion from lifting up when it is sealed.

When molding an IC with resin using the mold of this embodiment, the timing, speed, flow rate, etc. of the resin flowing from the upper mold gate 3a and the lower mold gate 3b are all set to be the same.

FIG. 2 shows packages (upper package 6a and lower package 6) after IC is resin-sealed with the mold of this embodiment.
(b) shows a perspective view of the exterior. 7 is an external lead pitch virtual line.

FIG. 3 is a perspective view showing the vicinity of a mold cavity in a second embodiment of the present invention.

In this embodiment, upper mold gates 3a are formed at both diagonal corners of the upper mold cavity 2a, and air vents 5a are provided at the center of each of the four sides of the cavity. Since resin burrs remain in the air vent 5a during resin encapsulation and adhere to the surface of the lead frame, the air vent 5a is inserted so as to pass through a part of the tie bar that connects adjacent leads, avoiding the lead portion that becomes the external lead of the package. will be established.

Regarding the lower mold, lower mold gates 3b are provided at both diagonal corners of the lower mold cavity 2b at positions not facing the upper mold gate 3a. The air vents 5b are provided at positions facing the air vents 5a of the upper mold.

According to this embodiment, the amount of resin that passes over the bonded wire can be kept smaller than in the first embodiment, so the amount of wire deformation can be kept to a minimum.

FIG. 4 shows an external perspective view of the package after resin sealing according to this embodiment. Gates are provided at four locations, two gates 3a on the upper mold and two gates 3b on the lower mold, and it can be seen that resin is injected from each gate.

〔Effect of the invention〕

As described above, the present invention can reduce the amount of resin flowing and passing through the same wire bonding area by arranging and forming a plurality of resin injection gates at symmetrical positions in one cavity.

Also, when trying to flow resin at the same flow rate, if there are two gates compared to one gate, the injection time will be halved by simple calculation, and if four gates are installed, the injection time will be It becomes 1/4.

As described above, when the resin injection time is shortened, it becomes possible to suppress changes over time in the resin viscosity during injection, and therefore the allowable range of variations in the encapsulation conditions becomes larger.

Due to the above factors, the stress exerted by the flowing resin on the bonding wire can be reduced, so deformation of the bonding wire during resin encapsulation can be significantly reduced, and reliability can be improved. Also, ICs with extremely narrow wire bonding pitch intervals and long bonding lengths
Even large package ICs can be easily encapsulated in resin.

cavity, 2b...lower die cavity, 3a...upper die gate, 3b...lower die gate, 4a...upper die sub-runner, 4b...lower die sub-runner, 5a...upper die Air vent, 5b...lower air vent, 6a...
・Upper package, 6b...Lower package, 7...
・External lead pitch virtual line.

Claims (1)

[Claims] In a pair of upper and lower semiconductor resin molding molds for resin-sealing semiconductor integrated circuit elements mounted on a lead frame after wire bonding, the resin injection gate into the cavity is positioned symmetrically with respect to the center of the cavity. 1. A mold for semiconductor resin encapsulation, characterized in that at least one set of the resin injection gates is arranged in the upper mold and the other resin injection gate is formed in the lower mold.