JPH0423442A - Mold for resin sealing - Google Patents

Abstract

PURPOSE:To prevent deformation of a stage and inner leads by holding either support bars of a lead frame or the inner leads thereof from above and below by support blocks when a bottom tool and a top force are made to abut on each other. CONSTITUTION:A bottom tool 1 and a top force 2 are provided with support blocks 6 projecting into their cavities respectively. When the bottom tool 1 and the top force 2 are made to abut on each other, at least either support bars 4a of a lead frame 4 or inner leads 4b thereof are held from above and below by the support blocks 6. Thereby a stage 4c supported in a suspended state in the cavities and, in addition, supported by the slender support bars 4a and also the inner leads 4b being numerous, slender and weak in a mechanical strength can be prevented from being deformed by inflow of sealing resin.

Description

[Detailed Description of the Invention] [Summary] Particularly regarding resin molding molds for semiconductor devices, the lower mold and -1- A resin sealing mold used to form a resin-sealed semiconductor device by sandwiching a lead frame on which a chip is mounted, the lower mold and the upper mold having respective cavities. It has a support block that protrudes inward, and when the lower die and the upper die are brought into contact with each other, at least one of the support bar and the inner lead of the lead frame is sandwiched from above and below by the support block. Configure.

[Industrial application field]

The present invention relates to a mold for resin encapsulation, and particularly for resin encapsulation of semiconductor devices, a mold that can hold a stage support bar or inner lead between an upper mold and a lower mold when setting a lead frame in the mold. is intended to provide.

In recent years, the progress of semiconductor devices has been remarkable, and the fields in which semiconductor devices are used are expanding rapidly.
The production volume of semiconductor devices is also increasing dramatically.

The mass production of semiconductor devices is largely dependent on manufacturing technology for a series of manufacturing processes from the wafer stage to the finished product as a semiconductor device.

The manufacturing process of semiconductor devices can be broadly divided into front-end processes and back-end processes.For example, the front-end process is from the die-cutting stage to the formation of a large number of fine elements, and the back-end process involves cutting the wafer into chips. From that point until the finished product.

Further, the post-process can be subdivided into the assembly process and the inspection process.
It is now said that post-processing determines the manufacturing cost of semiconductor devices.

The assembly process involves cutting the wafer into chips, mounting, bonding, sealing, and marking. As device patterns become finer, and as density and capacity increase, how to assemble chips efficiently and reliably has become an important issue.

In the assembly process, chip encapsulation is a so-called package that protects the element and takes out the lead-out terminals, and various forms and methods are used, but the most efficient and cost-effective method Since it is cheap, resin-sealed packages using molding technology are often used, and there is still much research needed to improve the efficiency of resin-sealing technology and the sealing equipment used to perform it, especially the molds used for sealing. There's room.

[Conventional technology]

For example, in resin sealing of semiconductor devices, a frame-shaped support member called a lead frame is generally used. First, the chip is mounted on a mounting section called a stage of the lead frame. Next, the pads of the mounted chip and terminal portions called inner leads of the lead frame are wire bonded with gold wire or the like. Then,
This is done using a type of insert molding in which the lead frame is set in a sealing mold and a sealing resin is poured into it.

FIG. 6 is a perspective view of the main parts of the lower mold and the lead frame stacked on top of the lower mold of an example of a conventional resin encapsulation mold, and FIG.
A partially enlarged perspective view of the figure, and FIG. 8 is a cross-sectional view of the case of resin sealing in FIG. 6.

In the figure, 1 is a lower mold, 2 is an upper mold, 3 is a chip, 4 is a lead frame, 5 is a cavity, 7 is a resin, and 8 is a wire.

The lower mold 1 and the upper mold 2 are abutted against each other with a lead frame 4 in between, and each is provided with a cavity 5 for shaping the shape of the molded product.

The lead frame 4 is made up of 6 or 10 pieces connected to form a sheet unit, and therefore the cavity 5
Six or ten of them are arranged in parallel.

On the other hand, the lead frame 4 is made by punching and forming thin strips or plates made of iron-based alloys or copper-based alloys, but the number of edges r- increases or becomes thinner, resulting in less precision. If required, it is made by chemical etching.

The lead frame 4 is provided with a stage 4C on which the semiconductor chip 3 is mounted, and inner leads 4b that are wire-bonded to the chip 3 with a wire 8 such as a thin gold wire.

Stage 4c generally consists of one and several supporting par 4s.
There are a plurality of inner leads 4b, which are connected in a frame shape by dam bars 4d such that two sides face inward or surround four sides, and the lead frame That is why it is called. The outer side of the dam bar 4d connected to the inner lead 4b is called an outer lead 4e.

During resin sealing, the inner lead 4b is placed on the stage 4c.
The outer lead 4e is enclosed in a resin 7 together with the chip 3 which is mounted and wire-bonded, and the outer lead 4e protrudes outside the resin 7 together with the dam bar 4d to serve as an external lead.

Incidentally, electronic components such as semiconductor devices are generally encapsulated with resin by transfer molding of thermosetting resin. The molding process of thermosetting resin is performed through three stages: plasticization, shaping, and curing.

That is, the resin 7 in the first stage is heated and plasticized in a pot (not shown) to reduce its viscosity and make it easy to flow.The resin 7 is then filled into the cavity 5 through a runner called a lunch. It is in the first stage of plasticization.

Then, in the second stage, the resin 7 is sufficiently filled to every corner of the cavity 5 and reaches a predetermined molding pressure.
A desired shape is formed.

This is followed by a third stage of curing, for example by a chemical reaction such as condensation polymerization or addition polymerization.

At this time, after the resin 7 is spread to every corner of all the cavities 5 arranged in a row and the molding pressure is uniformly applied to all the cavities 5, and the second stage is completed, the third stage of curing begins. desirable.

However, in semiconductor devices and the like, as the number of molded products that can be obtained in one molding process increases for mass production, the scale of the mold equipment also increases, and the resin 7 begins to harden before the fat is uniformly distributed. Things happen from time to time. In other words,
Depending on the cavity 5, a situation may arise in which the resin 7 flowing in is forced into the resin 7 as it hardens and becomes more viscous.

On the other hand, the lead frame 4 has an increased number of inner leads 4b, a thinner lead shape, and a lower mechanical strength. Furthermore, during normal resin sealing, what is held between the lower mold 1 and the upper mold 2 is the pole (near the inner side) of the dam bar 4d.

Therefore, the stage 4c and the inner lead 4b supported by the support bar 4a are supported in the cavity 5 in a suspended state.

Therefore, when the resin 7, which is in the process of curing and is increasing in viscosity, is pushed into the cavity 5 and flows, the stage 4c supported by the support bar 4a may be distorted, and the inner lead 4b may be bent as shown in FIG. Such transformations occur from time to time.

[Problem to be solved by the invention]

In this way, the number of leads in the lead frame has increased and the shape has become thinner, and the support bars that support the stage have also become thinner and have less mechanical strength. Because the molds are large in order to produce a large number of molded products, quite viscous resin may flow into some cavities, and the flow of resin may cause abnormal external forces on the stage and inner leads supported by the support bar. is added and deformation occurs.

This deformation has caused problems such as cracks in the package and breakage of the bonding wire, which can be fatal.

The present invention aims to provide a mold in which a stage support bar and an inner lead can be held between an upper mold and a lower mold when a lead frame is set in the mold.

[Means to solve the problem]

The problem described above is a resin encapsulation mold that has a lower mold and an upper mold and is used to sandwich a lead frame on which a chip is mounted to form a resin-sealed semiconductor device. The lower mold and the upper mold have supporting blocks protruding into their respective cavities, and when the lower mold and the upper mold are brought into contact with each other, at least one of the support bar and the inner lead of the lead frame This problem is solved by a resin sealing mold configured to be sandwiched from above and below by support blocks.

[For production]

In this way, in conventional resin sealing molds, the → port bar and inner leads are deformed by the abnormal external force of the inflowing resin, causing fatal failures. In the invention, the support bar and the inner lead are supported so as not to be deformed.

In other words, when a support block is protruded into the cavity of both the lower mold and the upper mold, and the two molds are brought into contact with each other, the support par and inner lead of the lead frame are pinched from above and below by this support block. I'm trying to get support.

In this way, the stage, which is suspended in the cavity and supported by the thin supporter, and the inner leads, which are many and thin and have weak mechanical strength, will be damaged by the inflow of the sealing resin. It can prevent deformation.

〔Example〕

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of the resin encapsulation shown in FIG. 1, FIG. 3 is an external perspective view of the semiconductor device shown in FIG. 2, and FIG. A sectional view of another embodiment of the present invention, FIG. 5 is an external perspective view of the semiconductor device of FIG. 4.

In the figure, l is the lower mold, 2 is the upper mold, 3 is the chip, 4 is the lead frame, 4a is the support par, 4b is the inch lead, 4c is the stage, 5 is the cavity, 6 is the support block, 7 is the resin, 10 is a semiconductor device.

The lower mold 1 and the upper mold 2 are adapted to abut against each other in a liquid-tight manner, and a plurality of cavities 5 are provided so as to face each other when they abut against each other.

The chip 3 is, for example, a semiconductor element.

The lead frame 4 is a sheet unit in which a plurality of leads are arranged in series, and the chips 3 are mounted one by one on each stage 4c supported by a support par 4a. Wire bonding is then performed between the chip 3 and the inner leads 4b.

On the other hand, in each cavity 5 of the lower mold l and upper mold 2,
The support block 6 protrudes so that the support par 4a and the inner lead 4b of the lead frame 4 are sandwiched and supported when they collide.

The thickness of the support block 6 with a draft angle is, for example, 1 m.
It is composed of m blocks and stands up from the bottom of the cavity 5.

Embodiment 1 In FIGS. 1 to 3, a stage 4c is supported by four support pars 4a, and inner leads 4b are arranged to surround it on four sides. In this case, four support blocks 6 are provided in the cavity 5.

When sealing with resin, the lead frame 4 on which the chip 3 is mounted is attached to the lower mold 1, and the upper mold 2 is abutted and clamped, and the support par 4a and inner leads 4b are fixed by the support block 6. be done.

The support block 6 stands in the cavity 5 like a screen, and each of the support blocks 6 of the two molds 1 and 2 has a pitch interval of the support par 4a and each inner lead 4b, and a lead frame 4. Since a comb-shaped gap of, for example, about 0.3 mm is opened by the thickness of the plate, there is no problem in filling the resin 7 into the cavity 5.

Further, in the resin package of the resin-sealed semiconductor device IO, there is formed a groove 7a through which the support block 6 has passed, as shown in FIG.
and the inner lead 4b are exposed.

However, this will not be a problem if the same corrosion-resistant treatment as the outer lead 4e is applied. Of course, if necessary, the groove 7a can be filled with adhesive resin or the like later.

Embodiment 2 In FIGS. 4 and 5, the support block 6 stands up from the bottom of the cavity 5 of each of the lower mold I and the upper mold 2 via two legs.

If the support block 6 is configured to float above the bottom of the cavity 5 in this way, a long groove will not be formed in the external appearance of the semiconductor device 10 after resin sealing as in Example 1. As shown in FIG. 5, holes 7b are formed.

The shape and arrangement of the support block can be modified in various ways depending on how the stage is supported and how the inner leads are arranged.

In this way, deformation of the stage of the lead frame and inner leads that occurs during resin sealing can be prevented.

〔Effect of the invention〕

As mentioned above, the support tools supported by the stage
If a lead frame whose mechanical strength has been weakened due to thinning or thinning due to an increase in the number of leads is sealed with resin using a conventional mold, the stage and inner leads may deform and cause problems. Whereas it was the cause of
According to the present invention, this problem can be prevented.

Therefore, the present invention provides, for example, when manufacturing a semiconductor device,
This greatly contributes to improving the yield of the resin sealing process, which is close to the final process.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is a sectional view of the resin sealing shown in Fig. 1, and Fig. 3 is a sectional view of the resin sealing of Fig.
FIG. 4 is a sectional view of another embodiment of the present invention, FIG. 5 is an external perspective view of the semiconductor device shown in FIG. 4, and FIG. 6 is a conventional resin encapsulating metal. A perspective view of the main parts of an example of a lower mold and a lead frame stacked on top of the lower mold, FIG. 7 is a partially enlarged perspective view of FIG. 6, and FIG. FIG. In the figure, ① is the lower die, 3 is the chip, 4 is the lead frame, 4a is the support par 5 is the cavity. 2 is the upper mold, 4b is the inner lead, 6 is the support block, r (7

Claims (1)

[Claims] It has a lower mold (1) and an upper mold (2), and is used to form a resin-sealed semiconductor device by sandwiching a lead frame (4) on which a chip (3) is mounted. A mold for resin sealing, wherein the lower mold (1) and the upper mold (2) have support blocks (6) protruding into their respective cavities (5), and the lower mold ( 1) and the upper mold (2), at least one of the support bar (4a) and the inner lead (4b) of the lead frame (4) is held between the support block (6) from above and below. A mold for resin sealing characterized by: