JPH02133932A - Premolded package and its manufacture - Google Patents

Abstract

PURPOSE:To simplify a production process by a method wherein a lead frame which is not provided with a dam connecting individual outer leads is inserted and molded by using a thermoplastic resin. CONSTITUTION:A premolded package is obtained by injection-molding a thermoplastic resin by using a specific molding metal mold. That is to say, protruding resin stoppers 6b are formed in corresponding parts between a plurality of outer leads 3b of a lead frame 3 to be inserted; one side face of the protruding resin stoppers 6 forms a face identical to a cavity 2 of the premolded package or is situated to be adjacent to the cavity 2. The individual outer leads 3b are set between the protruding resin stoppers 6b of the metal mold and are inserted and molded; thereby, it is possible to simply manufacture the extremely excellent premolded package. It is possible to prevent a resin from flowing out during a molding operation; it is also possible to solve the complicated problems such that a dam must be cut after the molding operation and that an unnecessary resin solidified between a case and the dam must be cut and removed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pre-molded package, and more particularly to a pre-molded package that has a dam between a plurality of outer leads and has a simplified manufacturing process, and a method for manufacturing the same. .

[Conventional technology and its problems]

A pre-molded package formed by insert molding a conventional lead frame is shown in Figure 3 in order to prevent resin from flowing out between the outer leads during insert molding and to maintain the strength of the leads. A dam 3a is provided between each outer lead 31 to connect them, and the distance between each outer lead is restricted. This dam 3a must be removed after insert molding, and in order to facilitate this removal, it is necessary to provide a gap with the side of the case, and since resin flows into this gap, unnecessary resin flows between the outer leads. It is also necessary to remove the dam 3a, and then the cap 1 is glued on to form a pre-molded package.
Cutting and removing unnecessary resin parts is a complicated process that requires extremely high precision, and if excessive force is applied during the process, the product may be damaged. It had become.

Furthermore, when a pre-molded package is manufactured using a thermosetting resin, gas is generated during solidification. Therefore,
A mold with a special gas venting structure must be used to pressurize and remove the gas, and this pressure tends to cause resin to flow out between the outer leads and form unnecessary resin parts.
There were also problems such as resin flowing out into the gas venting part.

In general, when molding pre-mold packages, it is unavoidable to use a high-temperature mold, and there is a difference between the temperature at which the product is released from the mold and the room temperature. During the cooling process, if there is a difference in linear expansion coefficient between the lead material (metal) and the resin material, stress is generated at the interface between them, causing a decrease in interfacial adhesion. In particular, the presence of a dam restricting the leads was a cause of increasing this thermal stress.

[Means to solve the problem]

The inventors of the present invention have completed the present invention as a result of intensive studies aimed at obtaining a pre-molded package that has improved the above-mentioned drawbacks.

That is, the present invention provides a pre-molded package formed by insert molding a lead frame that does not have a dam connecting each outer lead, and a method for manufacturing the same.

The pre-molded package of the present invention can be obtained by injection molding a thermoplastic resin using a specific molding die.

That is, in the mold used in the present invention, a convex resin stopper is formed at a location corresponding to a plurality of outer leads of the lead frame to be inserted, and one side of the convex resin stopper is the same as the cavity of the pre-molded package. It is arranged so as to form a surface or close to the cavity.

By setting each outer lead between the convex resin stoppers of this mold and performing insert molding, the above-mentioned defects can be improved and an extremely excellent pre-molded package can be easily manufactured. .

FIG. 2 shows a schematic cross-sectional view of an example of a mold used in the present invention.

That is, in FIG. 2, a dam 3a is attached to the outer lead 3b in FIG.
When performing insert molding using a lead frame 3 that does not have a lead frame 3, the mold is equipped with a convex resin stopper 6a that prevents resin from flowing out between the leads. It is clearly distinguished from the conventional mold shown in Figure 4.

The shape of this convex resin stopper may be as long as the height is equal to the thickness of the lead frame and the width is equal to the dimension between the outer leads.
is formed flush with the cavity or close to the cavity. In particular, it is preferable that one side of the convex resin stopper be formed on the same surface as the cavity. It is also possible to provide a clearance for the dimensions of this convex part, taking into account the ease with which resin flakes appear and the operability of inserting and releasing the lead frame, and these dimensions can be adjusted as appropriate depending on the shape of the resin and lead frame. It is desirable to select

In FIG. 2, an example is shown in which the convex resin stopper 6a is provided at the upper end of the lower die 6, but of course the convex resin stopper 6a is provided on the upper die 5.
It may be provided at the lower end of the .

On the other hand, the structure of the lead frame itself is not particularly limited, and its thickness may be within the normal range (0.1 to 0.5 mm), but in terms of strength, it is recommended to use one that is as thick as possible. preferable.

A perspective view of the pre-molded package of the present invention thus obtained is shown in FIG. Incidentally, the cab 1 may be bonded after insert molding using an epoxy adhesive or the like as in the conventional case. Furthermore, although FIG. 1 (and also FIG. 3) shows an example of a dual in-line package in which leads are attached to two opposing sides of the case, in the present invention, leads are attached only to one side or two leads are attached to only one side. It may also be of a type with leads attached to the sides.

By using the mold of the present application, resin leakage during molding, which is a drawback of conventional dams, can be prevented, and the process of cutting the dam after molding and cutting and removing unnecessary resin solidified between the case and the dam can be avoided. This makes it possible to simplify the production of pre-molded packages.

In addition, unlike conventional products, by providing a convex resin stopper on the mold side without installing a dam, there is no distortion caused by restraint between the outer leads, and the mold is released from the mold at a particularly high temperature. Thermal stress that occurs when the lead is cooled down to a certain temperature is alleviated, and the reliability of the adhesion between the lead and the resin is improved.

Further, according to the manufacturing method using such a mold, the molding resin and molding conditions for insert molding are not particularly limited, and any thermoplastic resin can be used. However, considering that the product will be mounted on a printed circuit board, etc., solder heat resistance, solvent resistance, etc. are also required, and a thermoplastic resin that satisfies these requirements has melt processability that can form an anisotropic melt phase. Polyester (liquid crystalline polyester), especially aromatic polyester or aromatic polyester amide containing aromatic hydroxycarboxylic acid group or aromatic hydroxyamine group as at least one of the resin constituents, polyarylene sulfide represented by polyphenylene sulfide,
Thermoplastic resins such as polyamide, polyethersulfone, polysulfone, polyetherimide, and polyetheretherketone can be mentioned. These thermoplastic resins can be used alone or in combination of two or more.

Further, these thermoplastic resins may be supplemented with other thermoplastic resins.

The thermoplastic resin used in this case is not particularly limited, but examples include polyolefins such as polyethylene and polypropylene, aromatic polyesters made of aromatic dicarboxylic acids and diols or okynecarboxylic acids such as polyethylene terephthalate and polybutylene terephthalate;
Polyacetal (homo or copolymer), polystyrene, polyvinylchloride polyamide, polycarbonate, A
Examples include BS, polyphenylene oxide, and fluororesin. Further, two or more of these thermoplastic resins can be used in combination.

The molding material suitable for the present invention has mechanical strength and can be molded at low pressure, and as mentioned above, it means that it can be filled with a large amount of inorganic filler in order to make the coefficient of linear expansion as close to that of metal as possible. Also, it is preferable that the melt viscosity is as low as possible. From these points of view, melt-processable polyesters (liquid crystalline polyesters) capable of forming an anisotropic melt phase, especially aromatic polyesters containing at least one resin component of an aromatic hydroxycarboxylic acid group or an aromatic hydroxyamine group, or Polyarylene sulfides represented by aromatic polyesteramides and polyphenylene sulfides are most preferably used.

The thermoplastic resin for insert molding used in the present invention includes:
Various inorganic/organic fillers may be included in order to improve strength, etc., within a range that does not impair the purpose of the present invention. For example, substances added to general thermoplastic resins, ie, fibrous, powdery, or plate-like fillers, are used.

Fibrous fillers include glass fiber, asbestos fiber,
Silica fiber, silica/alumina fiber, zirconia fiber,
Examples include inorganic fibrous materials such as silicon nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and titanium fibrous materials.

Note that high melting point organic fibrous substances such as fully aromatic polyamide fibers, aromatic liquid crystalline polyester fibers, and phenol fibers can also be used in the same manner as the inorganic fibrous fillers.

On the other hand, examples of powdery fillers include carbon black, silica, quartz powder, glass peas, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, and iron oxide. , metal oxides such as titanium oxide, zinc oxide and alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, etc. can give.

Furthermore, examples of the plate-like filler include mica, glass flakes, and the like.

These inorganic fillers can be used alone or in combination of two or more.

When using these fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this include functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used after surface treatment or convergence treatment, or may be added at the same time when preparing the material.

The amount of inorganic/organic filler used is 95% by weight or less, preferably 20 to 75% by weight, based on the resin.

Furthermore, in order to improve various properties such as mechanical, electrical, chemical properties and flame retardancy, various additives and reinforcing agents can be added as necessary.

In addition, the thermoplastic resin for insert molding used in the present invention further has low distortion and stress during molding and solidification, and during use with rapid temperature changes, and adhesion to the object to be sealed. Therefore, silicone can be added. The term silicone used here refers to silicone oil, silicone rubber, and silicone resin. These are polyorganosiloxanes in which the side chains of dimethylpolysiloxane, the main component, such as part of the methyl group and/or at least part of the end of the main chain are hydrogen, alkyl groups, aryl groups, halogenated alkyl groups, halogen those having an aryl group, an amino-modified alkyl group, a mercapto-modified alkyl group, an epoxy-modified alkyl group, a carboxyl-modified alkyl group,
It may be substituted with one or more of polyether-modified compounds, alcohol-modified compounds, and ester-modified compounds, or it may have a crosslinked acid or graft structure.

〔Example〕

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to these.

Example 1, Comparative Example 1 A lead frame with a dam on the outer lead (Comparative Example 1) and a lead frame without a dam (Example 1) were used in the molds shown in FIGS. 4 and 2, respectively. Fused silica 4 with an average particle size of 20 μm is added to liquid crystalline polyester A described below.
Insert molding was performed using a resin composition containing 4% by weight and 2% by weight of silicone rubber (described later), and then the cap 1 was adhered with epoxy resin to produce a pre-molded package as shown in FIG. In addition, in Comparative Example 1, the dam was cut before adhering the cap.

When the following gross leakage test was conducted on the pre-molded packages obtained in this way, it was found that there was no leakage from the interface between the leads and the resin in Example 1 out of 100, whereas in Comparative Example 1 there was no leakage from the interface between the leads and the resin. All 100 pieces were leaked.

(Gross leak test) 100 samples were immersed in a high-temperature Fluorinert solution at 130° C., and the adhesion between the lead and resin interface was evaluated based on the number of samples in which bubbles were generated from the lead and resin interface.

Examples 2 to 7 In place of the liquid crystalline polyester A of Example 1, other liquid crystalline polyesters (B-G), which will be described later, were similarly evaluated, and results equivalent to those of Example 1 were obtained.

The liquid crystalline polyester used in the examples has the following structural units.

The silicone rubber used in the examples was obtained by adding dimethylpolysiloxane having vinyl groups at both ends and dimethylpolysiloxane having -8i-tl in a part of the polysiloxane chain in the presence of a platinum compound catalyst. It is a powder-like silicone rubber (average particle size: 8 μm) crosslinked by reaction.

〔Effect of the invention〕

The pre-molded package of the present invention does not require cutting the dam between the outer IJ and the outer lead after insert molding, and also eliminates the need to remove unnecessary resin parts between the outer leads, thereby simplifying the manufacturing process. It is.

Furthermore, the adhesion between the lead frame and the resin package has been improved, making it suitable for use in various electrical and electronic components such as ICs.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pre-molded package using a lead frame without a dam according to the present invention, and FIG.
A sectional view taken along the line A-A' in the figure and a diagram showing the state of a mold having a convex resin stopper used in the present invention to prevent the resin from flowing out between the leads. Figure 3 is a pre-mold with a conventional dam. FIG. 4 is a perspective view of an example of the package, and is a cross-sectional view taken along the line B-B'' in FIG. 3 and a diagram showing the state of the mold. 1: Cap 2: Resin case 2a: Cavity 3: Lead frame 3a : Dam 3b: Outer lead 3C: Inner lead 3d: Island 4: Unnecessary resin leaked between the leads 5: Upper mold 6: Lower mold 6a: Convex resin stopper provided at the upper end of the lower mold 6b: One side of 6a forms part of the cavity of resin case 2.

Claims (1)

[Claims] 1. A method for manufacturing a pre-molded package, characterized in that a lead frame without a dam connecting each outer lead is insert-molded using a thermoplastic resin. 2. In the method for manufacturing a pre-molded package according to claim 1, insert molding is performed using a mold in which a convex resin stopper is formed at a position corresponding to between a plurality of outer leads of a lead frame to be insert molded. A method for manufacturing a pre-molded package characterized by: 3. The method for producing a pre-molded package according to claim 1 or 2, wherein the thermoplastic resin is a melt-processable polyester (liquid crystalline polyester) or polyarylene sulfide capable of forming an anisotropic melt phase. 4. A pre-molded package formed by insert molding a lead frame without a dam connecting each outer lead using thermoplastic resin. 5. The pre-molded package according to claim 4, wherein the thermoplastic resin is a melt-processable polyester (liquid crystalline polyester) or polyarylene sulfide capable of forming an anisotropic melt phase.