JPH02106952A - Electronic device - Google Patents

Abstract

PURPOSE:To prevent the local collection of static electricity on the surface of a material and the electrostatic breakdown of the electronic part of the inside, and to obviate permeation into a molding material of moisture from the outside by forming a film having the resistivity of 1X10<6>-5X10<13>OMEGAcm onto the surface of an organic resin. CONSTITUTION:A film (a DLC film) 43 composed of carbon having the resistivity of 1X10<6>-5X10<13>OMEGAcm or mainly comprising carbon is shaped onto the whole surface and rear of an insulating organic-resin molding material 41 having the resistivity of 10<17>OMEGAcm in the thickness of 0.05-5mum. Since there are an organic gas, chlorine and moisture, which deteriorate reliability, in the molding material 41 on molding, all of these substances are evacuated first and removed to the outside. The rear of the molding material is sputtered by an insert gas such as argon, neon, helium, krypton, etc., or nitrogen and activated, and the DLC film is formed through a plasma CVD method.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" This invention provides an organic resin malt treatment to the entire electronic components such as semiconductor integrated circuits after wire bonding.
In order to prevent static electricity from locally accumulating on the surface of this insulating mold (indicating resin molding or resin sealing after mold F), internal electronic components would be damaged by static electricity, and external In order to prevent moisture from penetrating into the mold material, a layer of 1 x 106 to 5 x 1013 Ωc is applied to the surface of the mold material.
It is provided with carbon or a coating mainly composed of carbon and having a specific resistance of m.

Therefore, the present invention provides plasma CV using carbide gas.
Using the O method, a carbon or carbon-based coating with good thermal conductivity and excellent adhesion to organic resin molding materials (also abbreviated as DLC because carbon has the same sp3 bond as diamond) ) is applied.

"Prior Art and its Problems" FIG. 4 shows a frame lead (35) and a frame guide (35') in which a conventional organic resin mold (41) is made.

In the drawing, this organic resin (41) is lXl0"Ωc
Because it is an insulating material with a high resistivity (also called specific resistance) of more than m, it is used in SMT (Surface Mount Technology) to avoid contact with the surface of the jig during assembly or contact with the mold material during storage. Static electricity has accumulated locally on the surface. When the thickness of the organic resin is thick, the electric field strength of this static electricity becomes relatively small for electronic components, and electrostatic damage to electronic components is less likely to occur. However, the thickness of the mold material is 1
．． When the thickness is 5 mm or less, the electric field strength due to static electricity becomes relatively large and cannot be ignored from the viewpoint of ensuring the reliability of electronic components.

Furthermore, the die (35°) to which the IC chip (28), which is an electronic component, is die attached is made of metal such as copper or 4270I, and the electronic component (28) is die attached (24 ) A lower oxide (32) is formed during the heat treatment at 100 to 450°C.

Therefore, immediately after this, the organic resin molding material (4
When the molding process according to 1) is performed, an oxide layer (
32) will remain. If this electronic device is stored for a long period of time, the malt material absorbs moisture from the atmosphere and collects near the oxide (32). Therefore, the crank (33) could not withstand the rapid thermal shock during soldering at 260°C for 13 to 10 seconds in the subsequent process, and the mold material around the die was cranked (33).

(33') was generated, and moisture accumulated on the back side of the die was vaporized to form voids (42), and blisters (41') were generated in the malt material on the back side. and PCB
When used for a long time after being mounted on a semiconductor device, the ingress of water and impurities from the crank part causes deterioration of the characteristics and reliability of the semiconductor device.

However, these matters have not been considered at all so far.

``Structure of the Invention'' In order to prevent local destruction of electronic components caused by static electricity and deterioration of reliability due to occurrence of cranks, etc. that occur in conventional DIP, the present invention provides a unique Resistance 1 x 10b ~ 5 x 1013
It is coated with a film having ΩC11. This is coated with carbon or a coating mainly composed of carbon that has good adhesion to the organic resin.
It is formed to a thickness of m. In order to form this film, the molded electronic device is evacuated in advance.
Vacuum degas the moisture in the mold material. The upper surface has weak insulation properties to prevent static electricity, and to prevent water from entering from the outside, it is coated with carbon or carbon-based coating (DLC).
The film is characterized in that it is coated as a protective film using a plasma CVD method that uses a vacuum and produces a sputtering effect.

In the present invention, before forming the organic resin molding material, the entire lead frame and chip may be covered with a silicon nitride film or the like using a plasma treatment method to produce a more reliable electronic device.

FIG. 1 shows a longitudinal sectional view of a plastic old P (dual rain line type package or flat package) having the structure of the present invention.

In the drawing, an electronic component chip (2) is attached to a die (35') of a lead frame using an organic resin silver paste (24), a glass-based silver paste, or a gold-silicon alloy method.
8) and the aluminum pad (38) of this chip.
and the metal lead (stem) (35) with a gold wire (39).
) wire bonding was performed.

Furthermore, for higher reliability, the surface of the chip (28), the surface of the pad (38), the surface of the wire (39), and the surface of the die (3
Lower oxides and natural oxides generated during die attach are removed by plasma treatment with non-product gas on the back side of the metal plate (30), exposing the metal surface (30), and a protective layer is placed on top of this to prevent deterioration. films, especially silicon nitride films (2
7) Coating by plasma CVD method (27'') is performed.

After forming a protective film for preventing deterioration such as a silicon nitride film to a thickness of 300 to 5,000 layers, generally about 1,000 layers, an organic resin such as epoxy (for example, 410B) is coated by a known injection molding method. was injected and sealed. Furthermore, the frame is bent at the lead portion (37) and the tie bar is cut. After acid-washing the lead portion, the lead was solder-plated.

After these, DLC (43) having a specific resistance of 1 x 106 to 5 x 10'3 Ωcm is applied to the entire front and back surfaces of the insulating organic resin molding material (41) of the present invention having a specific resistance of 1017 Ωcm. is formed to a thickness of 0.05 to 5 μm.

The molding material (41) contains organic gases, chlorine, and moisture that reduce the credibility of the mold. In order to remove these, the whole is first evacuated and removed to the outside. Then, DLC is applied to this surface by plasma CVD method.
Perform film formation.

The plasma processing method of the present invention uses the plasma processing method shown in FIG. Then, the surface was activated by sputtering with an inert gas such as argon, neon, helium, or krypton, or nitrogen. Furthermore, by plasma CVD method, D
The LC film was formed as a protective film (43'') to a thickness of 0.05-5 μm, preferably 0.1-1 μm.

A protective film such as this DLC film is made of carbon fluoride (
C and F such as CzFa, CzFs, CHP+, Cfl□F2
) and hydrogen, or a mixture of these carbon fluorides and ethylene (C, Il, ) from 1/4 to
The mixture was mixed at a ratio of 4/1, for example, 1/1, introduced into a plasma reactor, and formed by a so-called plasma vapor phase method in which electrical energy was supplied thereto. In order to control the resistivity of the DLC film, in addition to carbon hydrides such as ethylene, [1
ztli, [1(Cllz) *, Bh, NHs,
Nh.

N(Clls)+, N(Czll□)z, pHz, P(
A method of adding a valent or V-valent impurity such as CIl+)+ or a method of varying the position of the DC bias is effective. These two methods also made it possible to adjust the thermal expansion between the base mold material and the base mold material.

Figure 2 shows a substrate with a flat pack structure in which the chip of the present invention is bonded to a frame and coated with a molding material, and a substrate (1) in which a plurality of the chips are assembled (hereinafter, the substrate and the substrate are collectively referred to as the substrate). OLC 11
The outline of the apparatus for coating No. 51 is shown below.

In the drawing, a reaction system (50), a doping system (2)
0).

The reaction system has a reaction chamber (7) and a gate valve (9). The reaction chamber (8) blows reactive gas downward from the nozzle (25) of the hood (14) to perform a plasma reaction in the reaction space (8), and performs vacuum drying and molding on the substrate or substrate (1). The material surface was activated and a protective film was formed. After plasma treatment or reaction, the gas passes through the exhaust port (6) to the valve (21), turbomolecular pump (22), and vacuum pump (23).

A pair of high frequency power supplies (15-1), (15-2)
That is, the electric energy from (15) is 1 to 500 MH from the matching box (161) and (16-2).
For example, pass the frequency of 13.56 MIIz (4-1)
, (4-2) and is added to a pair of mesh electrodes (3-1) and (3-2) of the same size between the upper and lower sides. The phase of the high frequency power from each electrode is controlled within O@±30'' or within 180°±30° by a phase adjuster (26).If the surrounding frame structure holder (40) is a conductor, it is grounded. The reactive gas is excited by high frequency energy supplied by a pair of electrodes (3-1) and (3-2).In plasma processing and plasma CVD method , the object to be formed (1-1), (1-2)...(1-n), that is, (1) (hereinafter referred to as the substrate (2)) is a frame structure (40) disposed on the supporter (20). ) in parallel to the direction of the electric field between the pair of electrodes, furthermore, any electrode (3-1),
(3-2) and from the reaction vessel (7) using a condenser (9) or the like. The plurality of substrates (1) are arranged at constant intervals (2 to 13 cm, for example 6cn+) or approximately constant intervals.

To this substrate is an AC via 7 with a frequency of 50-100 KHz! , (17-1) and -50 to -2000V DC bias (17-2), that is, bias from bias current (17) is applied by connecting switch (10) to (11-2) to create DLC. . Hard 1×1Ob~5×1O
Application of this bias is extremely important to create a DLC with a resistivity of 11 Ωcm. The other ends of these power supplies are grounded (5-1) and (5-2).

(5-3) It has been done.

This large number of substrates (1) is arranged in a positive column in plasma created by glow discharge. The main part of this base body is shown in FIG. 3(C).

FIG. 3(A) shows a molding process (41) in which an electronic component (28) is bonded onto a metal lead seam (45) in which a plurality of stems (35) and dies (35') are integrated in a base (1). 5-2 electronic devices (29) after
It has 5 unitized frames (45). Figure 3 (B) shows a frame (substrate) of a certain part of one electronic device in one frame (45) to which a plurality of electronic components, such as semiconductor chips, are bonded and molded.
). A longitudinal cross-sectional view along line AA' is shown in (29) of FIG. 3(C).

In FIG. 3(C), a lead frame (35), a guide (35”), a semiconductor chip (2B), a metal wire (39
), an electronic device (29) made of malt material (41) from 5 to
25-unit frame (45-1), (4
5-2) Collect 5 to 300 more jigs (
44) to form a base (1). It is effective to cover the external connection portions with this jig so that they are not coated with DLC. This base (1)
are the base bodies (1-1) and (1-2) in Fig. 2.
- Corresponds to each of (1-n). In addition, 5 to 50 of these (7 in the drawing) are installed inside the Yoko company as shown in Figure 2.

In FIG. 2, the reactive gas flows from the hood (13-1) to the inside of the frame-structured holder (40) and the hood (13-1).
2) exhibits a plasma active state inside surrounded by
Plasma treatment is performed on the mold material to form a dense layer. A dense layer is formed as a protective film on this mold material.

As shown in FIG. 2, plasma CV in the method of the present invention
Prior to the formation of a DLC film by method D, the film was kept in an argon plasma solar room at room temperature, and the adsorbate was removed and the surface of the mold material resin was activated by plasma treatment with non-product gas.

Further, when forming a DLC film, a sufficiently dense layer can be formed by applying a bias without applying external heating.

An example of the process is shown below.

"Example 1" In the plasma CVD apparatus shown in FIG.
20) is a carbon fluoride, CtFb or C,FM from (20-1), and a nitride gas, N(C1li):
+ from (20-4), B(CHz)+ is (20-3)
Therefore, ethylene is supplied from (20-2) and hydrogen or argon, which is a non-product gas for plasma processing, is supplied from (20-5). They are flow meter (19), valve (1
8).

The substrate temperature was set to room temperature (including self-heating by plasma) without any active external heating.

First, the molded substrate shown in FIG. 3 was held in the reaction space (1), and argon was introduced. All of these I
A vacuum was drawn to below X 10-' torr (10 to 30 minutes) to degas organic gas, chlorine, and moisture in the molding material. The surface of the substrate (1), particularly the molding 1 (41), was subjected to plasma treatment. Here B(C1h)t or N(
CI+□):I/ (C2H4+C2F6) =O, 0
It was added at the same time as O13-0.03. That is, for these argon, IK with a frequency of 13.56 MIIz
The output of W is applied to a pair of electrodes (3-1) and (32) at 10 to 3
It was supplied for 0 minutes and turned into plasma.

A protective film of DLC was roughly formed on the substrate subjected to this plasma treatment. When forming a DLC film on a surface to be formed which has been subjected to plasma treatment as shown in Example 1, the reactive gas is, for example, Czl14/CJ6/Hz=1/1
It was set at 15. That is, for these gases, 13.56M
A pair of electrodes (11
), (11°). (And an average of 5,000 people (
5000 people ± 200 people) for about 30 minutes at an average speed of 3A/
A film was formed (seconds).

By increasing the AC bias voltage of 50KIIz, ±300V and the DC bias voltage from -50V to -2000V, the DLC film has a specific resistance of lXl0' to 5X10'3Ω.
It can be controlled down to cm. Further here NI+
3. B(CIL+): By adding 1 etc.
Good adhesion to the substrate and Vickers hardness of 500-3
000Kg/mm2 and 200-400Kg of mold material
/mm2.

For the electronic device obtained in this way, Noise Research Institute ESS
-6235 electrostatic breakdown tester was used to test the antistatic properties. IC is C7MOS memory 256KDIIAM
The thickness of the organic resin mold was 1.4 mm. Dl,C
has a thickness of 0.5 μm and a specific resistance of 109 to 1011 Ωc.
It was set as m.

The output voltage was set to ν at 20, and this was repeatedly applied to the DLC 900 times. The number of samples was 20. However, no electrostatic damage was observed.

On the other hand, for those that do not form the DLC of the present invention, the number of samples is 2.
0, but under the same conditions all input pins etc. were destroyed.

For the electronic device of the present invention, 85°C/85χ (relative temperature)
After leaving it for 1000 hours, soldering was performed at 260°C for 5 seconds. However, no cracks or blisters occurred in any of the 20 samples of this mold.

Of course, all the samples that were not coated with the DLC coating of the present invention had the defects shown in FIG.

In addition, in the present invention, the plasma processing method and the PCV
In the o method, not only electric energy but also 10 to 15μ
It is effective to use the FOCVD (or FPCVD) method, which uses light energy to which far infrared rays with a wavelength of 300 nm or less or ultraviolet rays with a wavelength of 300 nm or less are simultaneously added.

"Effect" In the present invention, as a dense film on the mold, 1X106
Bronze a DLC film with a specific resistance of ~5 x 1013 Ωcm: 1
When formed as a single layer, it is extremely slippery even when mounted in SMT. This tendency was particularly remarkable when DLC containing fluorine was formed on the surface.

Therefore, the present invention is also effective for automatic assembly. Furthermore, as mentioned above, even when 20 KV of suspicious static electricity was generated, the electronic device of the present invention did not suffer from any failure or destruction.

However, in the present invention, defects occurred in all 20 samples unless a protective film was formed. For this reason, coating with a DLC film for mold sealing was extremely effective. In addition, when performing plasma treatment, there is a vacuum degassing process for impurity gases and moisture in the mold material, so a reaction occurs between the moisture and chlorine in the organic resin and the metal of the die, resulting in the formation of lower oxides. , without the drawback of reducing reliability. This electronic device's P
When attaching a semiconductor to a CB using SMT, it was possible to prevent the mold material from swelling due to heating, as shown in the conventional example.

In the present invention, the electronic component chip is shown as a semiconductor element, but it may also be a resistor or a capacitor (and the bonding may be not only wire bonding but also flip chip bonding or solder bump bonding.

In the present invention, the chip may be large and may be molded without using a die. However, even in that case, it is effective to provide the DLC protective film of the present invention to cover all of the lead frame and chip as a base.

In the above description, a case is described in which a semiconductor chip is embedded on a lead frame, but the present invention is not particularly limited to a metal lead frame, and is applicable to hybrid ICs (11), film ICs, etc., where active elements or passive elements are embedded on a substrate. A similar effect can be expected for a substrate or base body on which an element is mounted and the entire body is molded.

[Brief explanation of drawings]

FIG. 1 shows a main part in a vertical cross section of a plus deck pancage semiconductor device after a moisture resistance test and a soldering test according to the present invention. FIG. 2 shows an outline of a plasma gas phase reactor for carrying out the method of the present invention. FIG. 3 shows an enlarged view of the carrier section of the apparatus shown in FIG. FIG. 4 shows a main part of a conventional plastic package in a vertical sectional view after being subjected to a moisture resistance test and a soldering test.

Claims (1)

[Claims] 1. In an electronic device in which an organic resin mold is applied to cover an electronic component such as a semiconductor integrated circuit, the surface of the organic resin has a ratio of 1×10^6 to 5×10^1^3 Ωcm. An electronic device characterized by forming a film having resistance. 2. An electronic device according to claim 1, wherein the coating is made of carbon or a material containing carbon as a main component and has a thickness of 0.5 to 5 μm.