JPS61120431A - Manufacture of package of semiconductor or the like - Google Patents

Abstract

PURPOSE:To obtain packages successively without producing a burr during the sealing process, by previously covering a semiconductor or the like with a synthetic resin, hardening it and disposing the semiconductor between sheets of thermoplastic resin. CONSTITUTION:Continuous sheets of thermoplastic resin 1 and 1' having a heat deformation temperature of 210 deg.C or over are fed from rolls and heated to be softened. The softened sheets are pressed by 5 and 5' to be provided with recesses 3 and 3', respectively. Synthetic resin has been previously applied to semiconductor chips 6 packaged in a lead frame 7 and been hardened. The sheets 1 and 1' and the lead frame 7 are supplied into a welding device 2 so that the chips 6 are received between a pair of the recesses 3 and 3'. U-shaped irons are positioned from both sides on the periphery of a pair of the recesses 3 and 3' so that the welding, cutting and sealing of the sheets 1 and 1' are performed simultaneously. If an inactive gas is supplied into the device 2 during these operations, the gas can be encapsulated simultaneously. The sealed package is discharged successively in the direction indicated by the arrow C. According to this construction, deburring and cleaning operations after the sealing can be omitted and a consistent manufacturing line can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a semiconductor package in which semiconductors are sealed with resin.

[Background technology]

Various encapsulating materials are used to protect semiconductor elements and ICs from external atmosphere such as moisture, heat, dust, and harmful substances, maintain electrical insulation, and prevent mechanical damage. Among these sealing materials, resins are often used because of their low cost. Thermosetting resins such as epoxy resins, silicone resins, alkyd resins, and phenol resins are used as resins for this purpose. Further, resin sealing methods include a casting method, a fluidized dipping method, and a transfer molding method, which are used depending on the object to be sealed. The most typical method is transfer molding using epoxy resin, which has excellent mass productivity.

When molding and sealing with a thermosetting resin, removing the thin particles that adhere to the leads after molding is a very troublesome process. In particular, efforts have recently been made to reduce the stress of sealing materials and improve lead adhesion, which is increasingly creating particles that are difficult to remove. In addition, the package is
al 1n-1ine package) to S OP
(small outline package)
With the change to FP (flat package) and FP (flat package), the lead strength has become weaker, making the deburring process more difficult.

This situation occurs during the guising process for wafers with semiconductor elements installed, the die bonding process for fixing the chips to the tabs of the lead frame, the wire bonding process for establishing conductivity between the chip electrodes and the leads, and the resin sealing process. This method continuously connects each process of the assembly process up to the post-processing process of the lead and the marking process, which is an obstacle to achieving complete automation.

As a method for making such an assembly process continuous, Japanese Patent Application Laid-Open No. 56-81957 discloses a method in which a semiconductor chip is protected in advance with a coating material and then sandwiched between upper and lower lids of thermoplastic resin that are separately injection molded. The manufacturing method that involves this process has been clarified. In this case, it is necessary to make various molded products depending on the shape of the semiconductor chip. Furthermore, in order to ensure reliability, great care must be taken to completely eliminate contamination caused by paris finishing of molded products.

JP-A-59-19358, JP-A-59-1935
The same thing can be said about the method shown in Publication No. 9.

[Purpose of the invention]

In view of the above, an object of the present invention is to provide a method for manufacturing a semiconductor package that does not generate paris during the sealing process and can perform the soil bonding process and subsequent processes continuously. .

[Disclosure of the invention]

In order to achieve the above object, the present invention, when sealing semiconductors to obtain a semiconductor package, coats the semiconductors with a synthetic resin composition in advance and solidifies the resin composition, and then The gist is a method for manufacturing semiconductor packages, which is characterized by packaging by sandwiching them between sheets made of a thermoplastic resin composition. below,
This invention will be explained in detail.

The semiconductors used in this invention are diodes.

Semiconductor elements such as transistors, integrated circuits of these semiconductors (IC, LSI, super LSI, etc.), hybrid ICs
There are various types such as, but it is not limited to these.

In this invention, various synthetic resin compositions are used to pre-coat the semiconductors depending on the required characteristics when sealing the semiconductors.

Among them, high heat resistance (heat deformation resistance and heat deterioration resistance),
It is preferable to have various properties such as low moisture permeability, electrical insulation at a certain level or higher, and low viscosity.Since it comes into direct contact with semiconductors, it is preferable to have a coefficient of thermal expansion close to that of semiconductors, and a coefficient of elasticity. Particularly preferred are those with a small value. Some examples of such resin compositions include epoxy resins, polyimide resins, and silicone resins, each of which can be used alone or in combination of two or more. In addition, these resins can be filled with glass fiber or the like as a filler to improve mechanical strength, and crystalline or amorphous silica, glass, Inorganic fillers such as titanium oxide and alumina are used as fillers to lower the elastic modulus, organic fillers of elastic materials such as rubber are used as adhesion improvers, and silane coupling agents are used as adhesive improvers to improve heat resistance. For this purpose, heat-resistant resin, etc., are applied separately, and 2
It is also possible to use a mixture of more than one species.

There is also a method of coating semiconductors with synthetic resin compositions.
Not particularly limited. For example, a method in which a liquid synthetic resin composition is applied by drip coating or the like and then solidified (including curing), or a method in which a pelletized synthetic resin composition is placed on a semiconductor, melted, coated, and solidified. and so on.

If semiconductors are coated with a synthetic resin composition in advance and the resin composition is solidified in this way, the semiconductors may be damaged or the wires of wire bonding may be cut when sandwiched between sheets of thermoplastic resin composition. This eliminates the need to depress the sheet.

Another advantage is that the reliability of semiconductors is further improved.

Various types of thermoplastic resin compositions are used in this invention depending on the characteristics required for semiconductor packages, but they have high heat resistance (heat deformation resistance and heat deterioration resistance), low moisture permeability, and It is preferable that the material has electrical properties, mechanical properties, and moldability of a certain level or higher. Some examples of these include ether resins such as polyphenylene oxide, polyether sulfone, polysulfone, phenoxy resin, and polyacetal; ester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyarylate; carbonate ester resins such as polycarbonate; Among polyamide resins, there are resins with low water absorption, such as polyphenylene sulfide (hereinafter abbreviated as PPS), and each can be used alone or in a mixture of two or more.

In addition, these resins can be filled with glass fiber or the like as a filler to improve mechanical strength, and crystalline or amorphous silica, glass, Inorganic fillers such as titanium oxide and alumina are used as fillers to lower the elastic modulus.
Elastic organic fillers such as silicone resin and rubber, silane coupling agents etc. as adhesion improvers, and heat resistant resins such as polyimide to improve heat resistance.
They can be used alone or in combination of two or more. In addition, the obtained semiconductor package is
It is often mounted on printed wiring boards, etc., and may be added to the solder bath when other circuit elements (resistors, capacitors, etc.) are soldered. At this time, it is not good if the package melts or gets damaged, so it is preferable that the heat deformation temperature of the thermoplastic resin composition is 210° C. or higher. However, the heat distortion temperature of 210℃ or higher is based on ASTM 0648 (18.6kg/cal
).

The sheet in this invention is not particularly limited, and various types can be used. For example, there are flat shapes that have the same extent in the vertical and horizontal directions, those that are wider in one direction than the other, ribbon shapes, film shapes, tape shapes, etc. Sh.

The thickness of the plate is also not particularly limited, and may be appropriately selected depending on the required characteristics for the semiconductor package.

Further, it is preferable that one or both of the sheets have a recess for accommodating the semiconductor at the time of sandwiching the semiconductor, since this makes it easier to sandwich the semiconductor. If the sheet is long, it is preferable to use it in the form of a roll, as this will reduce the area it occupies. In addition, when the sheet is made into a scroll, it is preferable not to provide the above-mentioned depressions because the scroll becomes less bulky. In this case, it is preferable to provide the above-mentioned depressions in the middle of extending the rolled sheet to the place where the semiconductors are sandwiched.There are various methods for providing the recesses in the sheet, and there are no particular limitations.

For example, there is a method of extending a sheet to a place where semiconductors are to be sandwiched (during the process, the sheet is heated and softened by appropriate means, and then immediately sandwiched (depressed) between molds to form a depression. The mold is the size of the semiconductor to be sealed,
It is preferable that the parts can be replaced in various ways depending on the shape, etc., since the same production line can handle high-mix, low-volume production. Of course, it is also possible to provide separate production lines depending on the mold. It is preferable that the sheet provided with the ridges as described above be cooled so as not to deform while being moved to the location where the semiconductors are sandwiched. The method for this purpose is not particularly limited, but for example, there is a method in which the sheet is placed on a steel belt, moved, and sent to a place where semiconductors are sandwiched.

The means for sandwiching the semiconductor between the sheets is not particularly limited either, and may be selected as appropriate. For example, a method of melting and bonding semiconductor chips by applying a tip-shaped soldering iron that is approximately l larger than the coated semiconductor to sandwich both sheets with the semiconductor part on the inside of the tip. First, a sheet is melt-bonded only on the back side of the board to be mounted, and after mounting the semiconductor chip and coating it with resin, cover it with another sheet and sandwich it with the previous sheet and melt-bond it. There are ways to do this.

In addition, the method of sandwiching and sealing semiconductors between sheets is not limited to melt bonding as described above, but may also be performed using other suitable means, such as
It is also possible to use adhesives.

Such adhesives are not particularly limited, and include, for example, resin compositions commonly used for encapsulating semiconductors. This resin composition is also preferable if it satisfies the above characteristics. However, since the manufacturing method of the present invention uses a thermoplastic resin composition, it is only necessary to cool it after melt-bonding and sealing, and no curing time is required as in the case of using a thermosetting resin. For this reason, it is preferable to employ fusion sealing because the time required for processing is also shortened.

The means for sealing gas into the semiconductor package is not particularly limited and may be selected as appropriate. For example, when a continuously fed sheet wraps semiconductor chips on a lead frame one after another, the gas may be released depending on the cleanliness of the atmosphere in the workplace or the atmosphere around the melting equipment. enclosed in the package. Alternatively, the gas to be encapsulated may be sent into or around the melt bonding device. The type of gas includes clean air, nitrogen gas, etc., and is not particularly limited, but from the standpoint of increasing reliability, inert gas is preferable, and the gas must be clean, free from dirt, dust, floating dust, etc. A dry gas (low absolute humidity) is preferred, and such an inert gas is preferred from the standpoint of increasing reliability.

Next, one embodiment of the manufacturing method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram thereof. As seen in the figure, the sheets 1 and 1' sandwiching the semiconductors are each long and shaped like a roll. These scrolls 1a and 1'
a to arrow A, respectively.

The sheets 1 and 1' are sent out by rotating in the direction B, placed on a steel belt (not shown), and sent to the melt bonding device 2. Along the way, the sheets 1 and 1' have recesses 3, 3. ... and 3', 3', ..., that is, heating devices 4 and 4'
Sheets 1 and 1' are heated and softened, respectively, and immediately thereafter, depressions 3, 3, . ... and 3Z3/, ... are formed. After this, sheet 1
and 1' are cooled by a steel belt (not shown) while being sent to the melt bonding device 2, respectively. Sheets 1 and 1' are each immediately before the melt bonding device 2,
It is preheated by a preheating device (not shown) and sent to the melt bonding device 2. This preheating is to facilitate and ensure melt bonding, and although it does not necessarily have to be performed, it is preferable to perform it. In the melt bonding device 2, the sheet 1
The sheets 1, 1' and the lead frame 7 are each fed into the melting device 2 so that the lead frame 7 with the semiconductor chip 6 mounted thereon is placed between the recess 3 of the sheet 1' and the recess 3' of the sheet 1'. (An enlarged plan view of this is shown in Fig. 2). The semiconductor chip 6 mounted on the lead frame 7 is coated with a liquid synthetic resin composition in advance, and the resin composition (not shown in FIG. 2) 9 is solidified (including hardening). ing. The tip of the joining mold of the melt bonding device 2 is a mouth-shaped soldering iron 8.8' larger than the size of the semiconductors to be sealed. These irons 8, 8' sandwich and heat the peripheries of the recesses 3, 3' of the sheet 1.1' holding the semiconductor chip 6 therebetween, and at the same time as melting and bonding, the sheets 1-1.1' are cut. and sealing is performed. At the time of sealing, the gas sealed in the semiconductor package can be changed in various ways by feeding gas into the melt bonding device 2 or adjusting the atmosphere. Furthermore, the method for cutting the sheets 1, 1'' during sealing is not particularly limited, and examples include a method using a cutter and a cutting method using heat during sealing.Semiconductor packages that have been sealed are At the same time, a lead frame 7 on which a semiconductor chip 6 to be sealed next is mounted is coated with a resin composition 9 and then fed into a sheet 1. 1' is also sent in. Such operations are repeated one after another.

FIG. 3 shows a semiconductor package that has been sealed.

As shown in the figure, the difference in the appearance of this package from that made using the conventional method is that there is a melt-bonded part 10 of the sheet that is the sealing material (the mouth-shaped part in Figure 3), which creates a step. That is what we are doing.

Since this is not Paris but a fused portion, there is no need to remove it in the next step. Also, lead 11.1
1. There is no Paris along the lines of... A-A' cross section of this semiconductor package is shown in FIG.
'A side of the cross section is the cross section of the part where the lead 11 comes out,
The A' side of the AA' cross section is a cross section of a portion between the leads 11. As shown in the figure, after the semiconductor chip 6 is coated with the resin composition 9, the following steps are taken: 1. 1' and sealed. As can be seen from the comparison between the right side and the left side in Figure 4, there is a slight protrusion of a portion of the sheet where the leads 11 are protruding, but this is not a problem in practice. It is.

Note that the manufacturing method of the present invention is not limited to this example, and there are various implementation methods. Some of them are mentioned above, but there are also others, for example, as shown in Figure 2, where the direction in which the sheet of sealing material is fed is perpendicular to the direction in which the lead frame on which the semiconductor chip is mounted is fed. The width of the sheet is also not a dimension corresponding to the length or width of one semiconductor to be encapsulated. The semiconductors to be encapsulated may have dimensions according to the length or width of multiple pieces. Flip-chip type, in which bumps are formed on the chip and the bumps are connected to the wiring pattern on the board by soldering; Au beam leads are attached to the semiconductor chip, and this beam and the wiring pattern on the board are connected by heat. There are beam-lead types that connect by crimp, and film carrier types that heat and press the semiconductor chip directly onto the inner wiring wired on an insulating film, and further bond the lead frame to the outer layer through this film.
There are various types of printed wiring boards, including those on which semiconductor chips are directly mounted along with other circuit elements (resistors, capacitors, etc.). The shape and size of the iron of the melting device.

The number also depends on the size and shape of the semiconductors to be encapsulated.

It can be changed in various ways depending on the number etc. The tip of the trowel can be flat, wedge-shaped, rounded, or concave depending on whether there is a lead or not (with a lead).
It may be convex (without leads), and various choices can be made. The pressure when sandwiching the sheet may also be adjusted as appropriate.

Next, Examples and Comparative Examples of the present invention will be shown, but the present invention is not limited to these Examples.

(Example 1) Using a 0.3fi thick PPS sheet, a comb-shaped aluminum model element, which had been drip-coated and solidified with epoxy sealing material in advance using the manufacturing system shown in Figure 1, was placed in a clean air atmosphere. It was fused and sealed. Depressing is at a temperature of 260-270℃, melting is at a temperature of 270-290℃
Each test was carried out at a temperature of Using the obtained semiconductor package, we conducted an accelerated life test at a pressure force of 133°C. As a result, open defects (broken wires) began to occur after 900 hours, and the defective rate at 1000 hours was 7%. Ta. Note that when the semiconductor element was melt-bonded and sealed using this method, there was no occurrence of patter on the leads, and no patter removal process or cleaning process was required. There was no need to modify the lead leg.

(Comparative Example 1) A semiconductor package was obtained by transfer-molding a comb-shaped aluminum wiring model element mounted on a lead frame using an epoxy sealing material based on a cresol novolak epoxy resin.

This semiconductor package required a deburring process and a cleaning process as post-processing. Using this semiconductor package, a moisture resistance life test was conducted at a pressure of 133°C. As a result, oven failure occurred after 700 hours, and the failure rate at 1000 hours was 10%.

As can be seen from the comparison between Example 1 and Comparative Example 1, the semiconductor package obtained by the manufacturing method of the present invention has moisture resistance reliability that is equal to or higher than that of packages made of epoxy resin sealing materials, which are currently most commonly used. Indicated. Furthermore, according to the manufacturing method of the present invention, there is no generation of paris, and therefore, there is no need for a pars removal process or a cleaning process after sealing.
You can proceed to the next step immediately.

〔Effect of the invention〕

As described above, in the manufacturing method of the semiconductor package of the present invention, when encapsulating semiconductors with a resin, the semiconductors are coated with a synthetic resin composition in advance, the resin composition is solidified, and then a thermoplastic resin is applied. Since the composition is sandwiched between sheets of the composition for sealing, there is no need to damage the semiconductors during sealing, there is no generation of paris, and there is no need for curing time after sealing. Therefore, the deburring process, cleaning process, etc. can be omitted, and the production line can be made continuous. This reduces the chances of contamination of semiconductors, and provides moisture-resistance reliability that is equal to or better than that of epoxy resin encapsulation, which is currently the most commonly used encapsulation material. The manufacturing method of the present invention can be applied even to packages with weak leads such as SOP and FP.

[Brief explanation of the drawing]

1st VI! J is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a partially enlarged plan view thereof, FIG. 3 is a plan view of the obtained semiconductor package, and FIG. 4 is a schematic diagram showing A of the same. -A'
FIG. 1.1'... Sheet of thermoplastic resin composition 2...
Melting bonding device 3, 3'... Recess for storing semiconductors 6... Semiconductor chip D... Lead frame 9... Coated resin composition 11... Lead agent Patent attorney Matsumoto Takehiko, Figure 2, Figure 3, Figure 1] Figure 4, 4. Gogekoho Seisho (self-published), January 18, 1985, Showa 59 case (2), No. 242012, Address: 1048 Kadoma, Kadoma City, Osaka Prefecture. given name
Name (50) Matsushita Electric Works Co., Ltd. Representative Tsunezono Tsuneko, Iku Hayashi 4, Agent 6, Specification subject to amendment 7, Contents of amendment (1) On page 11 of the specification, lines 4 to 5, `` "Substrate" should be corrected to "Lead frame."

Claims (5)

[Claims] (1) When sealing semiconductors to obtain a semiconductor package, the semiconductors are coated with a synthetic resin composition in advance and the resin composition is solidified, and then the sheet is made of a thermoplastic resin composition. A method for manufacturing semiconductor packages characterized by sandwiching and packaging them. (2) The method for manufacturing a semiconductor package according to claim 1, wherein the semiconductor package is sealed with an inert gas. (3) The method for manufacturing a semiconductor package according to claim 1 or 2, wherein at least one of the sheets sandwiching the semiconductor has a recess for accommodating the semiconductor. (4) The method for producing a package for semiconductors according to any one of claims 1 to 3, wherein the sheet of the thermoplastic resin composition is a long roll and is in a form that can be used continuously. . (5) The method for manufacturing a semiconductor package according to any one of claims 1 to 4, wherein the thermoplastic resin composition has a heat distortion temperature of 210° C. or higher.