JPH0864740A - Manufacture of ic lead frame - Google Patents

Abstract

PURPOSE: To provide the manufacturing method of a QFP-type IC package lead frame by which a stable lead frame which shows almost no contraction and whose leads show very little vertical and horizontal fluctuation can be obtained. CONSTITUTION: The manufacturing method is related to the manufacturing process of a QFP-type IC package lead frame which has 160 or more leads and includes a press-punching process of lead frame material. When the lead frame material which is wound into a coil form is continuously subjected to a required punching process while the lead frame material is paid off from the coil, a frame-cutting process by which the lead frame material is cut into required dimensions is eliminated. Further, before the tips of leads are cut, the lead frame material is subjected to an annealing treatment while a required tension is applied to the lead frame to remove the strain given by a punching process and then the tips of the leads are cut off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an IC lead frame, more specifically, the number of leads (number of pins) is 160.
The present invention relates to a method for manufacturing a lead frame for a QFP IC package.

[0002]

2. Description of the Related Art As one type of IC package, there is a QFP type IC package in which the package body has a flat quadrilateral shape and a large number of leads (pins) extend from each side of the four sides, and are widely used. There is.

When manufacturing the lead frame for the QFP type IC package, after the lead tip cutting process, which is the final step of press punching, the vertical direction of the leads (the direction perpendicular to the plate thickness) and Displacement in the horizontal direction (plate surface direction) occurs, which causes a problem in the subsequent steps such as wire bonding.

In the case of a lead frame for a QFP type IC package, particularly a lead frame having 160 or more leads (pin number), high shape and dimensional accuracy are required because the number of leads is large and the pitch is narrow. If the above displacement occurs during press punching, the shape and dimensional accuracy will deteriorate, and there will be the inconvenience that the steps such as wire bonding cannot be carried out satisfactorily.

Therefore, it is conceivable to perform annealing in the atmosphere before cutting the lead tip to remove the strain due to the punching up to that point. However, when the punched lead frame material is annealed in a state of being cut (frame cut) in a predetermined length dimension, the lead frame contracts in the longitudinal direction, which may make it difficult to perform the subsequent punching. This tendency is due to Fe-
This is particularly remarkable when a Ni-based alloy material is used.

It is considered that this is because atoms regularly arranged in the longitudinal direction (rolling direction) by the rolling process are randomly arranged by annealing.

In any case, if the annealing is simply performed to remove the strain, the subsequent steps such as punching or wire bonding cannot be performed well.

[0008]

The invention of the present application has been made in view of such circumstances, and there is substantially no contraction of the lead frame, and there is no displacement of the leads in the vertical and horizontal directions after cutting the tip of the lead. An object of the present invention is to provide a manufacturing method of a lead frame for a very small QFP type IC package.

Thus, the invention of the present application includes the step of press-punching the lead frame material, and the number of leads is one.
In a method for producing a lead frame for a QFP type IC package of 60 or more, when a predetermined punching process is continuously performed while the lead frame material wound in a coil shape is unrolled from the coil, the lead frame material is sized at predetermined intervals. Without performing frame cutting, and before finally cutting the lead tip, an annealing process is performed on the lead frame material with a predetermined tension applied in the longitudinal direction perpendicular to the plate thickness. Then, the distortion due to the punching process is removed, and then the cutting process of the lead tip is performed (claim 1).

According to another invention of the present application, in the manufacturing method of claim 1, the annealing treatment is performed at a temperature in the range of 500 to 700 ° C. (claim 2).

Still another invention of the present application is the manufacturing method according to claim 1 or 2, characterized in that the annealing treatment is performed in a state in which a tension of 3 kgf / mm ² or more is applied (claim 3).

Still another invention of the present application is the manufacturing method according to claim 1, 2 or 3, wherein the lead frame material is an Fe-Ni alloy material containing 30 to 55% by weight of Ni. (Claim 4).

[0013]

As described above, according to the present invention, when the lead frame material wound in a coil shape is unrolled from the coil and a predetermined punching process is continuously carried out, the punched lead frame material has a predetermined dimension in the longitudinal direction. Prior to the cutting, each piece is annealed at a predetermined temperature under tension applied in the longitudinal direction, and then the lead tip is cut.

When the annealing treatment is performed in accordance with the present invention, the strain generated by punching is satisfactorily removed, and, as will be apparent from the later examples, substantially no contraction in the longitudinal direction of the lead frame occurs. It has been confirmed. Therefore, according to the present invention, the subsequent wire bonding step and the like can be favorably carried out.

In the present invention, the annealing treatment is performed in the range of 500 to 7
It is desirable to carry out in the temperature range of 00 ° C (claim 2). The higher the annealing temperature, the greater the effect of strain relief, but 700 ° C
At higher temperatures, the hardness is significantly reduced and is lower than the desired value. On the other hand, when the temperature is lower than 500 ° C., it is difficult to obtain a sufficient annealing effect.

On the other hand, the tension applied during annealing is 3 kgf / m.
It is desirable that it is m ² or more (claim 3). If the tension is weaker than this, there is a risk of contraction in the longitudinal direction when the lead frame material is cut.

As described above, the contraction is apt to occur
This is especially the case when an Fe-Ni alloy material is used as the lead frame material, and therefore the present invention is particularly effective when applied to a lead frame material made of such an Fe-Ni alloy material. .

Here, as the composition of the lead frame material made of the Fe--Ni alloy material, Fe--42% Ni, Ni3, etc.
Those containing 0 to 55% by weight, specifically Ni: 30 to
A composition having 55% by weight and the balance substantially consisting of Fe is preferable.

However, if necessary, Nb: 1 to 5% by weight, C
It is also applicable to those containing O: 1 to 5% by weight and S: ≧ 0.005% by weight.

The reason why tension is applied to the lead frame material in the longitudinal direction during annealing is that shrinkage does not occur in the width direction even when ordinary annealing is performed without applying tension. Of course, shrinkage in the width direction hardly occurs even when annealing is performed by applying tension only in the longitudinal direction.

[0021]

EXAMPLES Examples of the present invention will be described in detail below. A leadframe material made of Fe-42% Ni wound in a coil shape is subjected to a predetermined punching process while being continuously fed out from the coil according to the present invention, and in that state, a strength of 3 kgf in the longitudinal direction is applied to the leadframe material. / Mm ² tension is applied and various annealing treatments are continuously applied at various temperatures.
Finally, the tip of the lead is cut and the number of leads (number of pins) is 1
Sixty lead frames for QFP type IC packages were manufactured.

Then, the displacement of the leads of this lead frame in the vertical and horizontal directions was measured. In addition, the change in hardness due to the annealing treatment was also obtained. The results are shown in FIGS. 1 to 3 in comparison with the case without annealing.

From these results, it can be seen that the displacement of the leads in the vertical and horizontal directions is very small by performing the annealing treatment under the condition that tension is applied in the longitudinal direction. At this time, the hardness also decreases, and the value is 7 when the annealing temperature is 7
If it exceeds 00 ° C., it becomes smaller than the desired value. Therefore, the annealing temperature is preferably 700 ° C. or lower.

Next, the dimensional shrinkage in the longitudinal direction after cutting the lead frame material when the tension and the temperature of the annealing treatment were changed was obtained, and it was as shown in FIG. from this result,
It is understood that shrinkage can be effectively suppressed by applying a tension of 3 kgf / mm ² or more.

The embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention can be implemented in variously modified modes without departing from the spirit of the invention.

[0026]

As described above, according to the present invention, it is possible to obtain a stable lead frame which has substantially no shrinkage and has a very small vertical and horizontal displacement of the lead, and also in IC manufacturing. The production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an annealing temperature and a vertical displacement obtained in an example of the present invention.

FIG. 2 is a diagram showing the relationship between the annealing temperature and the horizontal displacement obtained in the example of the present invention.

FIG. 3 is a diagram showing the relationship between annealing temperature and hardness obtained in the example of the present invention.

FIG. 4 is a diagram showing the relationship between the annealing temperature and the tension and the shrinkage obtained in the example of the present invention.

Claims (4)

[Claims] 1. A method of manufacturing a lead frame for a QFP type IC package having 160 or more leads, which includes a step of stamping the lead frame material, wherein the lead frame material is wound into a coil from the coil. When continuously performing a predetermined punching process while unwinding, the lead frame material is not subjected to frame cutting for cutting the lead frame material into predetermined dimensions, and finally to the lead frame material before cutting the lead tip. On the other hand, it is characterized in that an annealing process is performed in a state in which a predetermined tension is applied in the longitudinal direction perpendicular to the plate thickness, and the strain due to the punching process is removed, and then the cutting process of the lead tip is performed. Manufacturing method of IC lead frame. 2. The method of manufacturing an IC lead frame according to claim 1, wherein the annealing treatment is performed at a temperature of 500 to 700 ° C. 3. The method of manufacturing an IC lead frame according to claim 1 or 2, wherein the annealing treatment is performed in a state where a tension of 3 kgf / mm ² or more is applied. 4. The manufacturing method according to claim 1, 2, or 3, wherein the lead frame material contains Ni in an amount of 30 to 55% by weight.
% Fe-Ni alloy material is contained.