JP2884021B2 - Manufacturing method of electronic component mounting board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate for mounting electronic components,
In particular, the present invention relates to a method for manufacturing an electronic component mounting substrate configured by integrating an insulating base material on both surfaces of a lead.

[0002]

2. Description of the Related Art Various types of substrates for mounting electronic components have been proposed so far. Among them, after mounting electronic components, an outer lead portion is projected. In some cases, the whole is sealed with a so-called mold resin to form a so-called electronic component package 100 as shown in FIG. 3, that is, a semiconductor device. As such a substrate for mounting electronic components, the present applicant has formed an insulating base material integrally on both sides of a lead frame, and electrically connected a conductor circuit on the insulating base material and each lead through through holes. We have already proposed something that would be connected to the network.

In order to manufacture such a type of electronic component mounting board, an insulating base material must be integrated on both sides of the lead. The lead is made of metal and the insulating base material is usually made of synthetic resin. Since the prepreg is used, it is difficult to ensure the close contact between the two and to ensure durability in this state. So, conventionally,
Copper oxide, that is, a blackening film is formed on the lead side before the insulating base is integrated, and the blackening film on the lead side is used as a so-called anchor of the insulating base. In order to uniformly form the blackening treatment film serving as the anchor, pure copper is indispensable with the current effective technology. In particular, a metal plate not formed of pure copper (such as a lead frame and a lead frame) is used. Copper plating is a necessary operation.

A conventional method of manufacturing a substrate for mounting an electronic component in which an insulating base material is adhered using the above-described blackening treatment film has been performed as follows. That is, first, a lead frame with a large number of leads connected thereto is formed from a metal plate, and a copper plating layer having a thickness of 5 μm or more including plating variations, that is, an average thickness of about 10 μm is formed on the surface of the lead frame. . In order to form a blackening film on the copper plating layer, degreasing and soft etching are performed as a pretreatment on the copper plating layer, and the process proceeds to a blackening process. After that, an insulating base material is laminated with the completed blackening treatment film as an anchor, a conductive circuit is formed on the insulating base material, and the conductive circuit and each lead are connected through holes. Thus, each outer lead portion is exposed, and the blackened film and the Cu plating layer on the outer lead portion are removed by etching.

In the above-described conventional method of manufacturing a substrate for mounting electronic components, the following points have to be improved by the present inventors.

In the outer lead portion, etching for removing the blackened film and the Cu plating layer is performed.
It was found that the size was partially smaller than the specified size. This is an average thickness of 10 μm on the lead frame.
This is because it is necessary to completely remove the Cu plating layer. That is, the appearance of the surface is completely different between the Cu plating layer and the lead frame material due to the difference in the crystal structure, and it is not a good product when both are mixed. Therefore, the Cu plating layer having a thickness of 10 μm is completely removed. It is necessary to completely expose the timber.

Here, when the Cu plating is applied with an average thickness of 10 μm, the thickness of the thick portion is further increased due to the variation, and the thickness reaches 20 μm.

In order to completely etch the plating having a thickness of 20 μm, a variation in etching speed is added. In a portion where plating is thin from the beginning or a portion where etching speed is high, a portion of the original lead frame material is considerably etched. It will be smaller than the specified size.

[0009] Copper plating for uniformly forming a blackening treatment film and its blackening treatment, and the blackening treatment film and Cu
It takes a considerable amount of time to remove the plating, and the manufacturing time itself of the electronic component mounting substrate itself becomes longer as a whole. This is thought to be due to the fact that copper plating must be applied as much as 10 μm in the first place,
The reason why this copper plating must be applied as much as 10 μm is
This is because soft etching for blackening is required. In other words, in order to perform various operations such as storage and movement between facilities before the lead frame on which the 10 μm copper plating is formed is shifted to the blackening process,
Since the copper plating surface is oxidized and stained, degreasing and soft etching must be performed to remove these, and the copper plating thickness must be about 10 μm to withstand this. It is. This is considered to be the biggest cause of increasing the entire time for manufacturing the electronic component mounting board.

The electronic component mounting board is manufactured by using a large material such as a metal plate or an insulating base material, so that a so-called multi-piece manufacturing is performed. The above-described manufacturing steps for performing the steps are not omitted. In other words, it seems that the blackening treatment for bringing the insulating base material into close contact with the insulating base material may be prepared only for those parts which become the respective electronic component mounting substrates, but all such steps are performed individually. As a result, the number of processes increases, which eventually makes it unnecessary to take a large number of pieces.Therefore, it is better to integrate a large insulating base material into a series of lead frames and form each electronic component mounting board at the same time. Efficiency will be good.

Therefore, the present inventors have made various studies on how to reduce the time while ensuring the production of multiple pieces by devising the manufacturing process of the electronic component mounting board. As a result, the present invention has been completed.

[0012]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above circumstances, and an object of the present invention is to provide an electronic component mounting type of a type in which an insulating substrate is integrally formed on both sides of a lead. This is a reduction in manufacturing time when manufacturing a substrate.

An object of the present invention is to provide a good electrical connection because each of the insulating base materials is sufficiently adhered to each of the leads, and each of the lead frame portions exposed from the insulating base material is not thinned. It is an object of the present invention to provide a method of manufacturing a large number of electronic component mounting substrates, which has high reliability of electrical connection and can shorten the overall manufacturing time.

[0014]

Means for Solving the Problems and Actions In order to solve the above problems, the means adopted by the present invention will be described with reference to the reference numerals used in the embodiments. An insulating substrate 15 is formed integrally with the conductive circuit 16 and each lead 11 on the insulating substrate 15.
Are electrically connected to each other by through holes 17, and the electronic component mounting board 10 in which the outer lead portions 11a of the respective leads 11 project outward is manufactured through the following steps. A) A step of forming a lead frame 12 having a large number of leads 11 by etching or punching a metal plate into a predetermined shape; b) As a pretreatment, a copper plating 13 having a thickness of 1 to 2 μm is formed on the surface of the lead frame 12. Immediately after being applied to
3) a step of subjecting the lead frame 12 to a blackening treatment;
5 are integrated, and the conductive circuit 1
6) forming an electrical connection by means of the through holes 17; d) removing the portions of the insulating base material 15 covering the portions to be the outer lead portions 11a, and then exposing the outer portions. Step of removing the blackening film 14 on the surface of the lead portion 11a ”.

The lead frame 1 described here
Reference numeral 2 denotes a structure in which a large number of leads 11 constituting each electronic component mounting board 10 are integrated and further connected to each other. Are referred to as “individual lead frames 12”.

The manufacturing method according to the present invention is basically performed as shown in FIG.
For this purpose, it is necessary to first form a lead frame 12 having a large number of leads 11 by etching or punching a metal plate into a predetermined shape. In other words, as described above, many individual lead frames 12 corresponding to one electronic component mounting substrate 10 as shown in FIG. 1A are shown in FIG. It is necessary to form such a continuous one from a single metal plate. As a result, a base for obtaining a large number of electronic component mounting boards 10 is completed. In this lead frame 12, first, an individual lead frame 1 for forming one electronic component mounting board 10 is formed.
2 is formed as shown in FIG. 2, and a plurality of individual lead frames 12 are formed in a plane. Therefore, the insulating base material 15 described later is easily integrated with both surfaces of the lead frame 12.

The lead frame 12 as described above is
It is stored or transported as it is until the blackening process described below is performed, and no processing is performed immediately before the blackening process. Then, when the preparation for the blackening process is completed, as shown in FIGS. 1B and 1C, b) As a pretreatment, a copper plating 13 having a thickness of 1 to 2 μm is formed on the lead frame 12. Immediately after being applied to the surface, the copper plating 13 is subjected to a blackening treatment. What is important here is that the copper plating 13 is formed only as a so-called pre-treatment for forming the blackening film 14, and the copper plating 13 is formed immediately after the copper plating 13 is formed. Is subjected to a blackening process to form a blackened film 14.

Therefore, about 1 to 2 μm of the copper plating 13 as a pretreatment for the blackening treatment is sufficient. This is as follows when compared with the conventional manufacturing method. That is, in the conventional manufacturing method,
Although copper plating 13 which is pure copper for forming a uniform blackening film 14 on the surface of the lead frame 12 was plated, the copper plating 13 becomes dirty by oxidation or the like before the blackening treatment. Immediately before the blackening treatment, it was necessary to remove stains such as oxidation by soft etching. Copper plating with an average thickness of 10 μm was required so that the copper plating 13 would not be lost by the soft etching. In the manufacturing method of the present invention, since the copper plating 13 is formed immediately before the blackening treatment, the copper plating 13 does not become stained by oxidation or the like, and the copper plating 13 which is the minimum necessary for the blackening treatment film 14 is formed. The thickness of 1
A thickness of about 2 μm is sufficient.

Next, as shown in FIG. 2, c) an insulating base material 15 is integrated on both sides of the lead frame 12, and a conductor circuit 16 is formed on the insulating base material 15, The electrical connection by the through holes 17 is performed. This is a process in which when a large number of electronic component mounting boards 10 are individually taken out, each of them operates independently. The substrate may be formed by a method generally used at present, such as forming the substrate 10 at the same time, and may be performed using conventional equipment as it is. In the step (c), as shown in FIG. 1D, since each insulating base material 15 is integrated with each lead 11 via the blackening film 14, the respective lead 11 The adherence to is made firmly,
The durability when completed as the electronic component mounting substrate 10 is sufficient.

Finally, d) after removing the portion of each insulating base material 15 which covers each of the outer lead portions 11a, the blackened film 14 and the Cu plating on the exposed surface of each outer lead portion 11a are removed. The layer is removed to completely expose the lead frame material, and each outer lead 11
By separating a from the lead frame 12 for each electronic component mounting substrate 10, a large number of individually independent electronic component mounting substrates 10 are obtained. In this case, a sheet material such as release paper for facilitating the separation is interposed between an unnecessary portion of each insulating base material 15 and the lead frame 12, and both insulating materials for the lead frame 12 are separated. The base material 15 is integrated.

In the step d), the blackened film 14 and the Cu plating layer are removed from the surface of each outer lead portion 11a after the unnecessary insulating base material 15 is removed. The removal of the Cu plating layer 14 and the Cu plating layer is very easy because the original thickness was formed on the copper plating 13 having a thickness of 1 to 2 μm. The term “easy” means that the thickness of the blackening film 14 itself is thin, which means that the work time for removing the film by etching is shortened. This means that simple processing such as processing can sufficiently cope with the processing. Therefore, irrespective of the simple processing such as etching or acid treatment, the blackened film 14 and the Cu plating layer on the surface of each outer lead portion 11a are removed to completely expose the lead frame material. Is such that the outer lead portions 11a hardly become thin.

According to the manufacturing method of the present invention as described above, the time required to complete each electronic component mounting substrate 10 is greatly reduced. That is, if the conventional method is used, copper plating is applied to the entire surface of the lead frame for 5 to 10 days.
The thickness must be doubled, which is not only a time-consuming operation, but also requires soft etching as a pretreatment for the so-called thick copper plating blackening process,
In addition, both the blackening treatment of the thick copper plating and its removal took time. On the other hand, in the present invention, the thickness of the copper plating 13 is 1 / compared to the conventional one.
Since the thickness can be reduced to about 5/10, not only the time for forming the copper plating itself is shortened, but also since the copper plating 13 itself is a pretreatment for the blackening treatment, it is conventionally performed. This eliminates the need for soft etching, which is a pre-treatment of the blackening treatment, and furthermore, the time required for converting the copper plating 13 to the blackening treatment film 14 and the time required for the blackening treatment film 1
The time for removing 4 is also reduced. According to the actual work of the present inventors, the conventional method for manufacturing the electronic component mounting board 10 requires about 40 to 60
What took a long time, according to the method of the present invention, was about 30 minutes.
４０40 hours, the production time of which was considerably reduced.

[0023]

EXAMPLES The production method of the present invention will be specifically described below with reference to examples.

First, in order to form a lead frame 12 in which a large number of leads 11 are connected, a 150 μm-thick Cu
A required lead frame 12 was obtained by preparing a system lead frame material, applying a predetermined etching resist thereto, and performing an etching process. Note that, as in the present case, in a state where various tasks are separated, a supplier to the manufacturer of the electronic component mounting board 10 manufactures such a lead frame 12, and the electronic component mounting board 10 is manufactured. Since it is more efficient for the manufacturer of the 10 to process the lead frame 12 into the electronic component mounting board 10, the one delivered in this manner is also used in this embodiment. did. Of course, in the lead frame 12 at this stage, the material (Cu-based lead frame material) constituting the lead frame 12 is exposed as it is, and the copper plating 13 is not yet formed on the surface thereof. is there.

As a pretreatment for forming the blackening film 14 on the above-described lead frame 12, a predetermined degreasing or the like was performed, and then copper plating 13 was formed on the entire surface. The copper plating 13 may be formed by electroless plating or electroless plating, but is formed by electrolytic plating in the present embodiment, and has a thickness of about 1 μm. The lead frame 12 thus formed with the copper plating 13
In the next step, a blackening process was immediately performed in the next step, whereby a blackening film 14 was formed on the surface of each lead 11 as shown in FIG. Note that the blackening process itself employs a generally-used method.

Next, the outer lead portion 1 of each lead 11
A release sheet was disposed at a portion corresponding to 1a, and the prepreg-formed insulating base material 15 was thermocompression-bonded as shown in FIG. After that, the conductor circuit 16
Then, an unnecessary portion of the insulating base material 15 was removed by forming a through hole 17. The removal of the insulating base material 15 is performed by first forming a cut around the insulating base material 15 necessary for forming each electronic component mounting substrate 10 by using a laser beam.
This was performed by peeling off unnecessary insulating base material 15 by utilizing the releasing action of the release sheet placed in advance.

As described above, each lead 1
The outer lead portion 11a has a blackened film 1 on its surface.
4, the blackened film 14 and the Cu plating layer are removed by etching, so that the original material constituting the lead frame 12, that is, the Cu-based lead frame in this embodiment is removed. The material was exposed. As described above, in the present embodiment, the Cu-based lead frame material is used as the material of the lead frame 12, but even if all of the Cu plating is removed by etching, the width of the lead hardly decreases,
We were able to make products that meet the specifications.

Thereafter, a large number of individual electronic component mounting substrates 10 were obtained by separating each outer lead portion 11a from the lead frame 12. As shown in FIG. 3, necessary electronic components 20 are mounted on these electronic component mounting boards 10, and the respective electronic circuits 20 are connected to the respective conductor circuits 16 on the insulating base material 15 by bonding wires 21. Thereafter, the whole is sealed with the sealing resin 30 by a transfer mold type or the like, whereby the electronic component package 100 in which the outer lead portions 11a are exposed from the sealing resin 30 is formed.

[0029]

As described in detail above, in the present invention,
The feature is that a copper plating 13 is formed as a pretreatment of a blackening film 14 to be formed on the surface of each lead 11, and immediately thereafter, the copper plating 13 is blackened. Therefore, the adhesion of each insulating base material to each lead is sufficient, and each lead frame portion exposed from the insulating base material does not become thin, and the reliability of good electrical connection is high. Thus, it is possible to provide a manufacturing method capable of shortening the manufacturing time and obtaining a large number of electronic component mounting substrates.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of a lead frame and leads showing a manufacturing method according to the present invention step by step.

FIG. 2 is a partial perspective view showing a state where an insulating base material is integrated with both surfaces of a lead frame.

FIG. 3 is a cross-sectional view of an electronic component package configured using an electronic component mounting board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electronic component mounting board 11 Lead 11a Outer lead part 12 Lead frame 13 Copper plating 14 Blackening film 15 Insulating base material 20 Electronic component 30 Sealing resin 100 Electronic component package

Continuation of the front page (56) References JP-A-4-171750 (JP, A) JP-A-4-196261 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23 / 12-23/14 H01L 23/50

Claims (1)

(57) [Claims] 1. An insulating base material is integrally formed on both surfaces of a large number of leads, and a conductor circuit on the insulating base material and each of the leads are electrically connected by through holes.
A method of manufacturing an electronic component mounting board in which outer leads of the respective leads are projected outward through the following steps. A) a step of forming a lead frame having a large number of leads by etching or punching a metal plate into a predetermined shape; b) applying a copper plating having a thickness of 1 to 2 μm to the surface of the lead frame as a pretreatment. Immediately after this, a step of subjecting the copper plating to a blackening treatment; c) integrating the insulating base material on both sides of the lead frame, forming the conductor circuit on the insulating base material, Making the electrical connection by the through holes; d) removing the portions of the insulating bases that cover the portions to become the outer lead portions, and then blackening the exposed outer lead portion surfaces. A step of removing the processing film;