JPH0121627B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a resin-molded semiconductor device and a method for manufacturing the same, and aims to configure a semiconductor device having a molded package in which the occurrence of soft errors is extremely small. The peripheral side wall of the envelope from which the leads are led out is made of thermoplastic resin, and the inside is filled with high-purity resin containing no inorganic filler and sealed with a metal cap to form a package structure.

The manufacturing method consists of a step of injecting a thermoplastic resin into a continuous band-shaped lead frame in advance to continuously form an envelope, and then bonding a semiconductor chip to the lead frame and attaching wires. The method is characterized in that it includes a step of dropping a high-purity resin containing no inorganic filler into the inside of the envelope and bonding a metal cap at the same time.

[Industrial application field]

The present invention relates to a resin-sealed semiconductor device having a structure in which soft errors due to radiation irradiation do not occur, and a method for manufacturing the same.

[Problems to be solved by conventional technology and invention]

Conventionally, it has been known that when a semiconductor memory device is irradiated with alpha rays, a so-called soft error occurs, which disrupts the memory of a memory cell, and this is a fatal problem for memory devices. Alpha rays are emitted from radioactive elements that are contained in extremely small amounts in inorganic materials such as alumina (Al ₂ O ₃ ) and silica (SiO ₂ ) that make up ceramic packages. Measures are being taken to do so. On the other hand, resin-sealed (mold) packages, which are widely used as mass-produced products, contain about 70% of inorganic substances such as alumina, silica, and glass called filler in the resin material. Since the structure is in close contact with the semiconductor chip, there is a risk that soft errors may occur due to constant irradiation with alpha rays from these inorganic materials.For this reason, molded packages are rarely used in ultra-high-density storage devices. There is no such situation. Further, when using the device, consideration is given to forming a protective film on the surface of the device.

However, semiconductor memory devices that do not use a molded package, which are most suitable for mass production, have the problem of being difficult to reduce in price.

The present invention solves these problems and proposes a semiconductor device having a molded package and a method for manufacturing the same in which the occurrence of soft errors is extremely small.

[Means to solve the problem]

The problem is that it has a package structure in which at least the peripheral side wall of the envelope from which the leads are led is made of thermoplastic resin, the inside is filled with high-purity resin that does not contain inorganic fillers, and the package is sealed with a metal cap. The problem is solved by semiconductor devices.

In addition, the manufacturing method includes a step of injecting thermoplastic resin into a continuous band-shaped lead frame in advance to continuously form an envelope, and then adhering a semiconductor chip to the lead frame and attaching wires. After that, the method includes a step of dropping a high-purity resin containing no inorganic filler into the inside of the envelope and simultaneously bonding a metal cap.

[Effect]

Conventionally, a semiconductor device was created by bonding a semiconductor chip to a lead frame and attaching wires to the semiconductor element and hardening it with thermosetting resin to create a molded package.However, in the present invention, the peripheral side wall of the envelope is heated The structure of the semiconductor device is made of plastic resin, filled with high-purity resin, and sealed with a metal cap.

In this way, the occurrence of soft errors can be suppressed, and as with conventional molded packages, the manufacturing process can be easily mass-produced and the cost can be reduced.

〔Example〕

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 is a perspective plan view of a semiconductor device according to the present invention, in which 1 is a lead frame, 2 is a tie bar of the lead frame, 3 is an outer frame of the lead frame, 4 is a semiconductor chip, and 5 is an outer enclosure made of thermoplastic resin. On the side wall of the vessel, 6 is a high-purity resin, and 9 is a wire. This figure shows the pre-process of cutting and removing the tie bars 2 and outer frame 3 of the lead frame 1.

The following Figure 2 shows an enlarged cross-sectional view of one embodiment of the semiconductor device. In the figure, 1 is a lead (the lead frame is cut to become a lead), 4 is a semiconductor chip, and 5 is a The peripheral side wall of the envelope made of plastic resin, 6 is a high-purity resin filled inside, 7 is a metal cap, 8 is a metal plate forming the bottom of the envelope, 9 is a wire, and in this example, the bottom is made of metal. It has a structure with a board. With this structure, the semiconductor chip 4 is coated with a high purity resin, and since the high purity resin does not contain inorganic substances such as alumina and silica, there is no concern that soft errors will occur due to alpha radiation. As the high-purity resin, for example, a pure epoxy resin containing no inorganic filler is used, which is melted, poured into the interior, and cured. If the device is coated with such a thick layer of high-purity resin, even if a small amount of alpha rays are emitted from the thermoplastic resin used as the envelope, it will be blocked by the high-purity resin filled inside and cause a soft error. Normally, a resin with a thickness of about 300 [μm] is sufficient to block alpha rays.

Next, it is important to make the semiconductor device according to the present invention as low in price as possible, and the manufacturing method is as important as the structure. This will be explained step by step with reference to the manufacturing process diagram shown in FIG. In Figure 3, the process sectional view is shown on the left, and the process name is shown on the right.First, lead frame 1 (see a) is continuously supplied as a hoop material wound into a tape shape, and the lead frame is fed. Molds are set on the front and back sides, and molten thermoplastic resin is injected to form the peripheral side wall 5 of the envelope (see b). After the premolding is carried out one after another in this manner, the metal plate 8 is adhered to the bottom surface with an adhesive (see c).

Next, the semiconductor chip 4 is bonded to the lead frame inside the formed envelope by soldering or paste (see d), and the chip attachment is performed at a low temperature of 200°C. Next, in order to prevent the attached semiconductor chips from being destroyed, the lead frame is roughly divided into 8 to 10 lead frames in one sheet, and wires 9 are bonded using a known automatic bonding device (see e). Next, a high-purity resin, such as a pure epoxy resin without fillers, is melted at 150° C., dropped into the envelope (see f), and cured. Then, the resin will penetrate into every corner and solidify with good permeability. In the middle of this process, that is, while the high-purity resin is in a semi-molten state, a metal cap is placed on it and simultaneously bonded and solidified (see g). Then,
The outer frame and tie bars of the lead frame are cut and removed using a known method, and the leads are bent to complete individual semiconductor devices. These manufacturing processes can be easily automated by improving conventional methods, and the reason why we use a pre-molding process to create the envelope at the beginning of the process is to improve reliability and facilitate mass production. This is to make it easier.If you attach the semiconductor chips and wires and then mold them as in the past, there is a risk of damage to the semiconductor chips or wires due to high pressure being applied during the molding process or vibrations occurring. In the manufacturing method according to the present invention, after the pre-molding process is completed, in order to attach the semiconductor chip and perform wire bonding,
This has the effect of alleviating this problem.

Next, FIG. 4 shows a pre-molding process diagram of an important step of the manufacturing method according to the present invention, in which the automatically fed lead frame 1 wound in the form of a tape is connected to the upper mold 11 of the mold and the lower part. It is stopped between the molds 12 (see a), and the molds are moved from above and below to sandwich the lead frame, and a thermoplastic resin heated to 300° C. and melted is injected and molded (see b). after that,
When the mold is removed, the side wall 5 of the envelope is completed (see c). This pre-molding process can be used for mass production since lead frames can be pre-molded one at a time or a plurality of lead frames can be successively pre-molded at the same time.
In addition, this injection molding method allows easy temperature control and easy cost reduction. In addition, examples of thermoplastic resins include
PEEK (polyetheretherketone) is used, and PEEK is a resin with extremely good adhesive properties.
Note that there is a gap between the lead frame sandwiched between the upper and lower molds, but it is narrow, at most 0.1 to 0.2 [mm], so
It is held by the surface tension of the resin without leaking and is easily molded.

The following FIG. 5 shows a cross-sectional view of another embodiment of the present invention, and the same symbols are attached to the same parts in the figure. In this embodiment, the metal plate 8 is not used on the bottom surface, and the envelope 1 includes the bottom portion other than the metal cap.
This is an example in which all parts 5 are made of thermoplastic resin. The pre-molding process for the envelope 15 can be performed in the same manner as the above-mentioned manufacturing process by adhering the bottom part with a previously prepared thermoplastic resin.

It should be noted that the metal cap and metal plate constituting the semiconductor device according to the present invention are suitably made of an iron-nickel alloy material that has a thermal expansion as low as that of the lead frame, but there is no problem even if the material is not limited to this.

〔Effect of the invention〕

As is clear from the above embodiments, the semiconductor device according to the present invention can greatly reduce the occurrence of soft errors, can easily automate the manufacturing process, and can be manufactured at low cost due to low material costs. be. Moreover, it has good heat dissipation properties, eliminates the need to apply thick resin or the like as required in conventional soft error countermeasures, and reduces stress on semiconductor chips during the manufacturing process. Therefore, there is no problem in accommodating large chips, and the structure can be said to be extremely effective in reducing costs when applied to semiconductor memory devices and the like.

[Brief explanation of drawings]

FIG. 1 is a perspective plan view of a semiconductor device according to the present invention, FIG. 2 is a cross-sectional view of an embodiment of the semiconductor device according to the present invention, FIG. 3 is a manufacturing process diagram, and FIG. 4 is a pre-molding process diagram. , FIG. 5 is a cross-sectional view of another embodiment of the semiconductor device according to the present invention. In the figure, 1 is a lead frame or a lead, 2 is a tie bar of the lead frame, 3 is an outer frame of the lead frame, 4 is a semiconductor chip, 5 is a peripheral side wall of an envelope made of thermoplastic resin, and 6 is a filling material. High purity resin, 7 is a metal cap, 8 is a metal plate on the bottom of the envelope, 9 is a wire, 11 is an upper mold of a mold,
Reference numeral 12 indicates a lower mold of the mold, and reference numeral 15 indicates an envelope made of thermoplastic resin.

Claims (1)

[Claims] 1. A package in which at least the peripheral side wall of the envelope from which the leads are led is made of thermoplastic resin, the interior is filled with high purity resin containing no inorganic filler, and the package is sealed with a metal cap. A semiconductor device characterized by having a structure. 2 A process of continuously forming an envelope by injection molding a thermoplastic resin onto a continuous belt-shaped lead frame, and then adhering a semiconductor chip to the lead frame and attaching wires to the lead frame. 1. A method for manufacturing a semiconductor device, comprising the steps of: dropping high-purity resin inside an envelope and simultaneously bonding a metal cap.