JPS63157452A - Lead frame - Google Patents

Abstract

PURPOSE:To contrive improvement in tight adhesiveness of resin by a method wherein burning plating having low degree of smoothness is performed on the ordinary base plating on the whole or a part of the section to be tightly fixed to the resin of a lead frame. CONSTITUTION:A burning plating work is performed on the whole surface or a part of the tightly fixed surface of a lead frame 10 and resin. If the burning plating is performed directly on the lead frame material, a fragile film having poor tight-adhesive property and inferior heat-resisting property is obtained. Therefore, an ordinary plated film having the characteristics excellent in heat- resisting property and the like is used as the base plating of the burning plating, and the burning plating is performed on the above-mentioned base plating. As a result, the various characteristics of the burning plating can be improved. The range of area where the burning plating is performed is the all surfaces corresponded by an inner lead 14, a stage 16, and a stage support bar 18, for example. As the plated surface having low degree of smoothness is formed on the tightly adhered part of the frame 10 and resin through the above- mentioned processes, the tight adhessiveness of the resin can be improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a lead frame, and more particularly to a lead frame used in a resin-sealed electronic component package that houses electronic components such as semiconductor elements. , relates to a lead frame that has excellent adhesion to resin.

(Prior art) Semiconductor devices using resin-sealed electronic component packages are used by sealing semiconductor elements, inner leads of lead frames, etc. with resin, but semiconductor elements do not like moisture etc. Therefore, it is required to have excellent adhesion between the resin and the lead frame.

Conventionally, various measures have been taken to improve the adhesion between the resin and the lead frame.

For example, the types of plating applied to lead frames are being considered. That is, the adhesion of various plating films to resin has been compared and studied.

Furthermore, attempts have been made to form irregularities such as pear on the surface of the lead frame by pressing or etching to improve the physical adhesion between the lead frame and the resin.

(Problems to be Solved by the Invention) However, the above conventional means have the following problems.

In other words, it is effective to consider the type of plating to be applied to the surface of the lead frame, but there are problems in that selection requires time, such as the need to develop a new plating bath.

Furthermore, forming irregularities on the surface of the lead frame by pressing, etching, etc. makes it difficult to control the size of the irregularities, increases the number of steps, and contributes to cost-effectiveness.

The present invention has been made to solve the above problems, and its purpose is to provide a lead frame that has extremely good adhesion to resin and can be provided at low cost.

(Summary of the Invention) In the lead frame according to the present invention for the above-mentioned purpose, in the lead frame used for a resin-sealed electronic component package, at least the whole or a part of the portion that comes into close contact with the resin is burnt plated with a normal plating as a base. It is characterized by being subjected to

(Function) The unevenness of the burnt plating increases the physical bonding force with the resin and improves the adhesion with the resin.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 shows an explanatory diagram of the lead frame 10. As shown in FIG.

12 is an outer lead, and 14 is an inner lead.

Reference numeral 16 denotes a stage on which a semiconductor element (not shown) is mounted, and a rail portion 20 is supported by a stage support par 18.
, 20.

The semiconductor element mounted on the stage 16 is electrically connected to the inner lead 14 by wire bonding.

The region indicated by the dotted line in the figure is a resin sealing region, and the semiconductor element, inner leads 14, etc. are sealed in the resin.

A dam bar 22 works together with the molding die to dam the resin.

A feature of the present invention is that the entire or part of the surface of the lead frame 10 that is in close contact with the resin is burnt plated. Burnt plating refers to a plating film in which the crystal grains deposited at a higher current density than usual are coarse and the plating surface has poor surface smoothness.

Furthermore, if burnt plating is applied directly onto the lead frame material,
This results in a brittle film with poor adhesion and poor heat resistance. Therefore, in the present invention, a normal plating film having excellent properties such as heat resistance is applied as a base for the burnt plating, and the burnt plating is applied on top of this base plating.

This improves the properties of burnt plating.

Incidentally, if the thickness of the burnt plating is thick, it will naturally be dangerous even if there is an underlying plating, so the thickness of the burnt plating is preferably 1 μm or less.

As for the type of burnt plating, it is advantageous to use the same material as the base plating, since the burnt plating can be performed in the same bath following the base plating.

However, the burnt plating can be made of a different material from the base plating.

Types of plating include silver, nickel, copper, tin-nickel plating, and the like.

The range to which burn plating is applied is not particularly limited.

That is, the resin can be applied to the entire surface of the area to which the resin is to be adhered, for example, to the entire surface of the corresponding parts of the inner lead 14, stage 16, and stage sat bar 18.

If burnt plating is applied on the stage 16, it is presumed that it will hinder the fixing of the semiconductor element, but there is no particular problem in practical use.When fixing the semiconductor element on the stage 16 using solder, Plating actually exhibits good solder wettability and can firmly fix the semiconductor element.

If the burnt plating is an obstacle when fixing the semiconductor element, it is preferable to partially plate only the inner leads 14 with the burnt plating.

Further, the burnt plating may be applied to the entire surface of the lead frame 10. In this case, burnt plating is also formed on the outer leads 12, but as described above, the solder wettability of the solder applied on the outer leads 12 for external connection of the semiconductor device can be improved.

Next is wire bonding, as mentioned above.
When the burnt plating was applied to a thickness of about 1 μm or less on a good normal base plating, wire bonding was not hindered at all.

In the present invention, as described above, the part of the lead frame that is in close contact with the resin is baked and the plated surface has a low smoothness, so that the degree of adhesion with the resin is extremely good.

Incidentally, regarding the degree of adhesion between the lead frame and the resin in which the inner leads 14 were plated with ordinary silver, 2 to 3 out of 100 pieces were found to be defective. Regarding the degree of adhesion to the resin when plating was applied to a thickness of 0.1 μm, there were no defective products among 100 pieces.

(Effects of the Invention) As described above, according to the present invention, since the burnt plating with low smoothness is applied on the normal base plating, the physical bonding force between the resin and the surface of the burnt plating increases, We were able to provide a lead frame with excellent adhesion to the resin.

Furthermore, since the baking plating can be applied subsequent to the normal base plating process, there is no need for an additional process, and an inexpensive lead frame can be provided.

The present invention has been variously explained above using preferred embodiments, but the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of a lead frame. 10... Lead frame, 12... Outer lead, 14... Inner lead, 16...
Stage, 18...Stage support bar, 2
0...Rail part, 22...Dam bar.

Claims (1)

[Scope of Claims] 1. A lead frame used in a resin-sealed electronic component package, in which at least the whole or part of the portion that comes into close contact with the resin is burnt-plated using normal plating as a base. 2. The lead frame according to claim 1, wherein the base plating and the burnt plating are made of the same material.