JPH03296255A - Material for stamping - Google Patents

Abstract

PURPOSE:To offer a material for stamping with which a highly reliable device easy in manufacturing can be gotten by plating both sides of a conductive substrate material with palladium or alloy layers having palladium(Pd) for their main ingredients. CONSTITUTION:This material for stamping is one where both sides of iron-nickel alloy 10 called A-42 (alloy 42) 0.15mm in thickness are plated with Pd layers 12a and 12b about 0.5mum in thickness. For a lead frame where material for stamping is used, a uniform plating layer is formed in the inner lead, and a favorable plating area without leakage of plating to the side is formed. Moreover, since there is no necessity to do plating after stamping, the deformation of the top of the inner lead does not occur during carriage to the plating device, and a highly reliable lead frame can be gotten. Furthermore, the cost reduction by the shortening of processes becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a stamping material, and particularly to a stamping material used for manufacturing electronic components such as lid frames and connectors.

(Prior Art) A lead frame for a semiconductor device such as an IC or an LSI is formed by processing a metal strip into a shape using either a photoetching method or a non-blurring method, followed by a plating process.

Incidentally, as semiconductor devices become more dense and highly integrated, the chip area and the number of lead pins increase, but packages tend to remain the same as before or become smaller.

Therefore, the distance from the tip of the inner lead to the package line becomes shorter.

As the number of inner leads increases within the same area, the width of the inner leads and the distance between adjacent inner leads naturally become narrower. Therefore, deformation of the inner leads due to a decrease in strength and short circuits between the inner leads due to the deformation may occur.

Furthermore, in order to improve bonding properties, the tip of the inner lead and the semiconductor element mounting portion are often plated with noble metal.

As a result, the tip of the inner lead may be deformed during transportation to the plating equipment, and as shown in Figure 6, plating metal such as silver (Ag) may also adhere to the side surface of the tip of the inner lead, causing the plating area to overlap. Because the distance to the package line is short, migration occurs in the semiconductor device after mounting, causing short circuits between adjacent inner leads, which causes a decrease in reliability.

In order to solve this problem, by plating a precious metal such as gold on a predetermined position of the strip material and then forming it, it is possible to prevent the plating metal 9 from adhering to the side surface of the inner lead, and also to prevent the plating metal 9 from adhering to the side surface of the inner lead. A method of preventing deformation of the tip of the inner lead has also been proposed.

However, in this method, the tips of the outer leads must be further plated with solder in order to improve the soldering characteristics.

Furthermore, in this method, since plating is performed on a band-shaped material with an incomplete shape, it is difficult to confirm the positional shift, and there is a risk that a large number of defective products will be produced.

Therefore, a method of forming pilot holes for positioning prior to plating has been proposed, but this requires a stamping process to form the pilot holes, resulting in the need to perform stamping twice, which reduces productivity. There was a problem with it being bad. In addition, since the plated portion is stamped, it is easily scratched, resulting in a low yield.

A method has also been proposed in which a protrusion is provided on the plating mask after molding using a normal method, and the protrusion is inserted between the inner leads to prevent the plating solution from entering the side surfaces of the inner leads. However, this method also has problems in that if the inner leads and the protrusions of the mask do not match, the inner leads are deformed, the mask deteriorates quickly, and the cost is high.

In addition, in recent years, there has been a strong trend toward high-mix, low-volume production not only in the field of manufacturing lead frames but also other devices such as connectors.However, in any of these conventional methods, after receiving an order, it is necessary to go through a stamping process and then perform plating. Therefore, there was also the problem that it was not possible to reduce the time from order receipt to completion.

(Problems to be Solved by the Invention) As described above, as semiconductor devices become more highly integrated, the lead spacing continues to become smaller, and the adhesion of plating metal to the side surfaces of the inner lead tips reduces the reliability of semiconductor devices. It was causing this.

There was also the problem that the time from order receipt to completion could not be reduced.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide a stamping material that is easy to manufacture and allows a highly reliable device to be obtained.

Another object of the present invention is to provide a lead frame that preferably does not have plating metal attached to the side surfaces of the tips of the inner leads.

[Structure of the invention]

(Means for Solving the Problems) Accordingly, in the present invention, palladium (Pd) or an alloy layer containing palladium as a main component is deposited on both sides of a conductive base material, and this is used as a stamping material.

(Function) Palladium is a material that is difficult to oxidize and is extremely stable in the atmosphere, has good adhesion to underlying metals such as copper and nickel, and has extremely good solderability.

Therefore, for example, when forming a lead frame using this, it is completed only by stamping, and there is no need for plating as in the past, so there is no adhesion of plating metal to the side surfaces of the inner leads, and the process is completed during the plating process. This can prevent the tip of the inner lead from deforming.

In this way, it is extremely easy1 and in a short time from receiving the order.
It is possible to obtain a lead frame with uniform plating thickness and no plating on the side surfaces of the inner leads.

The same applies to other electronic components.

(Example) Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a stamping material according to an embodiment of the present invention.

This stamping material has a thickness of 0. A Pd plating layer 1 with a film thickness of about 0.5 μm is coated on both sides of an iron-nickel alloy 10 designated as A-42 (alloy 42) of 15'm+n.
．． 2a and 12b are applied.

Next, a method for manufacturing this stamping material will be explained.

First, an iron-nickel alloy plate designated as A-42 (alloy 42) having a thickness of 0.15 mm is cut into a predetermined width using a slitter.

Next, the iron-nickel alloy plates are sequentially immersed in a palladium plating bath, and both sides are plated with palladium to complete the stamping material shown in FIG.

Next, a method for forming a lead frame using this stamping material will be described.

FIG. 2(a) and FIG. 2(b) are views showing a lead frame formed using the stamping material of the embodiment of the present invention.

This lead frame includes a die pad 2, a plurality of inner leads 4 formed to face the die pad 2, an outer lead 8 extending outward correspondingly, a tie bar 7 that integrally connects these, and the like. Molded into the shape of a normal lead frame. 1 is a sidebar.

As can be seen from this figure, a uniform plating layer is formed on the inner lead, and a good plating area is formed with no plating leakage to the side surfaces.

Also, since there is no need to perform plating after stamping,
A highly reliable lead frame can be obtained without causing deformation of the inner lead tips during transportation to a plating device.

By shortening the process, it is possible to reduce the price.

If necessary, an insulating tape may be attached via a thermosetting resin so as to avoid the bonding area at the tip of the inner lead, and then cured and fixed through a heating process.

In this manner, a lead frame formed from the stamping material of the present invention can be obtained without plating metal adhering to the side surfaces of the tips of the inner leads, and no migration occurs.

Furthermore, there is no need to perform plating after stamping, and the process from receiving an order to completing the product can be completed in an extremely short time.

Furthermore, in the case of surface mounting as shown in Figure 3, even when the back side of the outer lead is directly fixed onto the circuit pattern of the mounting board, the Pd plating on the back side prevents solder from adhering. The properties are extremely good.

In the above embodiments, a dipping method was used to form the plating layer, but it is not necessary to use the dipping method, and it goes without saying that an electrolytic plating method may be used.

Further, in the above embodiment, annealing was performed after plating, but it may be performed before plating, after stamping, or both.

Furthermore, although A42 was used as the base material in the above embodiment, it is also applicable to base materials such as copper, nickel, and iron-nickel alloy.

It is also possible to perform a base treatment on the material and apply Pd plating.

Furthermore, although the material of the lead frame has been described in the above embodiment, it is not limited to the lead frame.
It is also applicable to devices such as connectors.

Furthermore, in the above embodiment, palladium (Pd) or an alloy layer containing palladium as a main component was deposited on the entire surface of the stamping material, but as shown in FIG. 4, the area corresponding to side par 1 was excluded. The entire surface may be plated. This makes it possible to save on materials. Furthermore, as shown in FIG. 5, spot plating may be performed on areas corresponding to the inner lead forming area, outer lead forming area, and die pad forming area (here, an example in which lead frames are formed in two rows) is also possible. ). The plating area is indicated by M in FIGS. 4 and 5.

In addition, Pd plating may be applied not only to both sides but also to one side in the case of PLCC3OD (film chip carrier), etc.

0 [Effects of the Invention] As explained above, according to the present invention, palladium (Pd) or an alloy layer containing palladium as a main component is deposited on both sides of the conductive base material. It is a material that is difficult to oxidize and is extremely stable in the atmosphere, has good adhesion to underlying metals such as copper and nickel, and has extremely good soldering characteristics, allowing the formation of highly reliable devices in a short time. It is possible to do so.

Furthermore, it is possible to form a highly reliable lead frame with uniform plating thickness and no plating adhering to the side surfaces of the inner leads.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a stamping material according to an embodiment of the present invention;
2(a) and 2(b) are views showing a lead frame made of the same material, FIG. 3 is a main part view showing an example of mounting a semiconductor device, and FIGS. 4 and 5 are views of the present invention. 6 is a diagram showing a modification of the stamping material, and FIG. 6 is a diagram showing the tip of an inner lead of a frame formed by a conventional method. 1...Zydobar-2...Die pad, 4 leads, 7...
・Tie bar 8...Outer 9...Support bar 10
... Base layer, 12b... Pd plating layer, M... Plating area. 2...Inner 2

Claims (1)

[Scope of Claims] A stamping material comprising: a conductive base material; and palladium or an alloy layer containing palladium as a main component deposited on both sides of the base material.