JPH04255261A - Outer lead connection structure of electronic component mounting board - Google Patents

Abstract

PURPOSE:To provide an outer lead connection structure where a solder bridge is hardly generated between leads so as to constitute the electronic component mounting board of an electronic component package. CONSTITUTION:Pads 14 provided to conductor circuit layers are alternately located, outer leads 15 are formed independent of the pads 14 and bent enabling the joints of the leads 15 to be located corresponding to the pads 14 respectively, and the joints and the pads 14 are connected to each other with solder 16.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a board for mounting electronic components formed by sandwiching a lead frame between insulating base materials, and in particular, the present invention relates to a board for mounting electronic components, in which the lead frame is separated into an inner lead frame portion and an outer lead frame portion. The present invention relates to a connection structure for outer leads in an electronic component mounting board configured as follows.

0002

[Prior Art] There are various substrates for mounting electronic components on which electronic components such as semiconductor elements called chips are mounted and the electronic components are sealed with resin to form a so-called electronic component package. Something has already been proposed and put into practical use. Among these, the applicant has integrated an insulating base material on both sides of a lead frame that integrates a large number of leads, and electrically and selectively connects the conductor circuit on this insulating base material and each lead using through holes. We have already proposed a board for mounting electronic components that is designed to do this. The electronic component mounting board that the applicant has already proposed is
It has various advantages such as easy manufacture and effective use of space on the insulating base material.

On the other hand, electronic component mounting substrates for configuring electronic component packages, including those proposed by the applicant as described above, are made by forming a plurality of electronic component mounting boards in series. Efficient mounting of parts and sealing with resin, etc. are carried out. In this case, if we consider a lead frame as an example, if there is a partial defect in this lead frame, the entire series of lead frames will become defective.

[0004] Therefore, the applicant has developed an electronic component mounting board of the type that integrates an insulating base material on both sides of a lead frame as described above, by converting the lead frame into an inner lead that integrates a large number of inner lead parts. It consists of a frame part and an outer lead frame that integrates an outer lead part that is formed separately and is electrically connected to each inner lead part, and in the final stage, each inner lead part It has already been proposed to configure the terminal and the outer lead portion to be electrically connected. As a result, if, for example, there is a defect in the inner lead part, only the inner lead frame part containing the inner lead part can be replaced with a good part, making it possible to make use of other parts, thereby reducing the overall cost. I was able to do that.

[0005] However, according to subsequent studies by the present inventors, it has been found that the electronic component package has multiple pins, that is,
As it becomes necessary to increase the number of leads, especially outer leads that protrude outward from the sealing resin, it becomes difficult to electrically connect the inner lead frame portion and the outer lead frame portion described above. This is what I discovered. In other words, solder is generally used to electrically connect the outer lead to each inner lead, but if the distance between each inner lead is short to accommodate a large number of pins, If it is too small, bridges are likely to be formed by the solder, and once a solder bridge is formed, the product cannot be used.

Therefore, the inventors of the present invention have developed a method for soldering when increasing the number of pins while taking full advantage of the fact that the lead frame is composed of an inner lead frame section and an outer lead frame section separate from the inner lead frame section. As a result of various studies on how to solve the bridge problem, the present invention was completed.

[0007]

Problem to be Solved by the Invention The present invention has been made based on the above-mentioned circumstances, and the problem to be solved is to connect the inner lead frame portion and the outer lead frame of a board for mounting electronic components. This is the occurrence of solder bridges when the frame is separated.

[0008]An object of the invention is to simplify the connection structure of outer leads without causing solder bridges between the leads when configuring an electronic component mounting board for configuring an electronic component package. The aim is to provide this through a unique structure.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the means taken by the present invention are explained by adding the reference numerals used in the embodiments. This is a connection structure for connecting an outer lead 15 formed separately from the mounting board 10 to a pad portion 14 on each conductor circuit layer side. The connecting portions of the outer leads 15 are bent to correspond to the pad portions 14 of each conductor circuit layer, and these connecting portions and pad portions 14 are connected with solder 16. A connection structure for outer leads 15, characterized in that the outer leads 15 are connected to each other by the outer leads 15.

That is, in the electronic component mounting board 10 according to the present invention, the lead frame, which was conventionally formed as an integral piece, is first separated into an inner lead frame portion 12 and an outer lead frame portion 13. An insulating base material 11 is integrated with the inner lead frame portion 12 to form a structure having a plurality of conductive circuit layers. Then, pad portions 14 having different positions (heights) are formed on the plurality of conductor circuit layers formed in this way, and the outer lead frame portion 1 is arranged so as to correspond to each of these pad portions 14.
The connecting portions of the portions that are to become the outer leads 15 of No. 3 are bent, and each pad portion 14 and each outer lead 15 are electrically connected by, for example, solder 16.

[0011]

According to the connection structure of each outer lead 15 configured as described above, first, the lead frame is connected to the inner lead frame portion 12 and the outer lead frame portion 1.
It can be divided into three parts,
This makes it possible to partially replace each component when a plurality of electronic component mounting substrates 10 are formed in series. In other words, since the inner lead frame section 12 and the outer lead frame section 13 can be configured as separate parts, for example, if there is a defective part on the inner lead frame section 12 or outer lead frame section 13 side, It is now necessary to replace only the defective part. Therefore, this connection structure can fully exhibit the advantages of dividing the lead frame into the inner lead frame section 12 and the outer lead frame section 13.

Furthermore, since this electronic component mounting board 10 has a plurality of conductive circuit layers formed by the inner lead frame portion 12 and the like, it can cope with the recent increase in the density of electronic components 20 and the like. It goes without saying that a large number of conductor circuits can be formed by alternately positioning the pad portions 14 formed on each conductor circuit layer and alternately connecting the outer leads 15 to be connected to each of these pad portions 14. Since it is bent, the solder 16 between each pad portion 14 and the outer lead 15 is removed as shown in FIGS. 1 and 2.
The connecting parts are three-dimensionally separated from each other. Therefore, in this connection structure, even if there is surplus solder 16 connecting the pad portion 14 and the outer lead 15, this solder 16 will remain attached to that portion when reflowed. There is no possibility of forming a bridge with the reflowed solder 16 in other parts. In other words, according to the connection structure of the present invention, each outer lead 15 is reliably connected to each pad portion 14 by the solder 16.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the connection structure according to the present invention will be explained in detail with respect to each embodiment shown in the drawings.

(Embodiment 1) FIGS. 1 and 2 show an electronic component mounting board 10 constructed using the connection structure of the present invention. An inner lead frame section 12 is used, which is formed by connecting a large number of inner lead sections with tie bars or the like, and an insulating base material 11 is integrated on both sides of the inner lead frame section 12. In this electronic component mounting board 10, a conductor circuit is formed by etching the metal foil attached to the surface side of each insulating base material 11, and a predetermined connection between the conductor circuit and the inner lead frame portion 12 is formed. It is connected to the inner lead part through a through hole.
As a result, a plurality of conductor circuit layers (three layers in this embodiment) are formed by the surface side of each insulating base material 11 and the inner lead frame portion 12 itself.

Further, in this electronic component mounting board 10, as shown in FIG. A pad portion 14 is formed at the tip of a part of the insulating base material 1 in this embodiment.
The pad portions 14 on the conductor circuit layer side on the top 1 and the pad portions 14 on the inner lead frame portion 12 side are alternately formed every other pad. Of course, when forming the pad portions 14 alternately, it is not necessary to form the pad portions 14 every other place at every location as in this embodiment, but it is possible to form the pad portions 14 every other place, for example, or to form them in a mixture. Needless to say, it's fine.

[0016] In addition, for the structure in which the insulating base material 11 is integrated on both sides of the inner lead frame portion 12 and the necessary conductive circuit layers are formed, various electrical checks are carried out at this stage. It is something that is done. The inspection is performed using, for example, each pad section 14, and checks whether or not the electrical connection of each section such as through holes is properly made. As a result of the check,
If there is a defective part somewhere, the inner lead frame part 12 with the insulating base material 11 integrated on both sides will be removed and replaced with another good product, since it is useless to connect each outer lead 15 to be described later. It is exchanged with

On the other hand, as shown in FIG. 2, the necessary number of outer leads 15 to be connected to each pad part 14 are integrated into an outer lead frame part 13 using tie bars. After the connection is completed or after the electronic component package 30 is completed using the sealing resin 21, the tie bars shown in the figure are removed, so that each outer lead 15 is ultimately considered to be independent. What is important about each of these outer leads 15 is that each outer lead 15 in this embodiment
The tips of the two are alternately bent as shown in FIG. In this embodiment, this bending is performed at the same time when the metal plate to be each outer lead 15 is punched out using a die to form the outer lead frame portion 13. In this embodiment, the amount of bending of each outer lead 15 to be bent is made larger than the distance between the top and bottom of each pad portion 14 shown in FIG. By doing this, each outer lead 15
When the tip of the pad 14 is connected to each pad portion 14 with the solder 16, the connection can be made reliably.

After positioning the outer lead frame portion 13 constructed as described above so that the tip of each outer lead 15 is positioned on each pad portion 14, the outer lead frame portion 13 is positioned on each outer lead 15 side or each pad portion 14 in advance. Pad part 1
By reflowing the solder 16 plated on the 4 side, electrical connections were made between each outer lead 15 and the pad portion 14, thereby creating the electronic component mounting board 10 as shown in FIG. be.

As shown in FIG. 1, on the electronic component mounting substrate 10 formed as described above, an electronic component 20 is mounted on a predetermined portion thereof, and the electronic component 20 is connected to, for example, an insulating substrate. After connecting the conductive circuits on the material 11 with bonding wires or the like, the electronic component 20 is sealed with a sealing resin 21 to form the electronic component package 30. In this electronic component package 30, each outer lead 15 protrudes from the sealing resin 21, but since each protruding outer lead 15 does not have a bent portion, each outer lead 15 protrude on the same plane, and enable surface mounting of the electronic component package 30, for example.

(Example 2) FIG. 3 shows Example 2 of the present invention.
This electronic component mounting board 10 has two conductor circuit layers separated by respective insulating base materials 11. In this embodiment, the conductor circuit layer located between both insulating base materials 11 is the inner lead frame section 12 described in the above embodiment 1, and this inner lead frame section 1
By making the external shapes of the conductor circuit layer 2 and the conductor circuit layer located on the lower side in the figure different, a pad portion 14 is formed which is exposed at the end of each conductor circuit layer.

Further, each outer lead 15 to be connected to the pad portion 14 of each conductive circuit layer is formed in the same manner as in the first embodiment, and in this embodiment, the outer lead 15 is formed on the bottom side in the drawing. It is constructed by bending the tip of the outer lead 15 corresponding to the pad portion 14 located downward in the figure.

[0022] In this second embodiment, the same parts as those in the first embodiment are designated by the same reference numerals as used in the above explanation in FIG. 3, and detailed explanation thereof will be omitted.

[0023]

[Effects of the Invention] As detailed above, in the present invention,
As explained in each of the above embodiments, the components of the lead frame are formed separately into the conductor circuit layer and the inner lead frame section 12, and the pad section 14 formed on each of the plurality of conductor circuit layers is formed separately for each layer. At the same time, the tips of the outer leads 15 integrated as the outer lead frame part 13 are bent corresponding to the pad parts 14, and the pad parts 14 and the outer leads 15 are soldered together. 16, there is no need to form a solder bridge at each connection.

Furthermore, the pad portion 1 of each outer lead 15
Since the connection to 4 is made with the above structure, the lead frame can be divided into the inner lead frame part 12 and the outer lead frame part 13.
This not only makes it possible to sufficiently cope with the increase in the number of pins of this type of electronic component mounting board 10, but also enables the replacement of the inner lead frame section 12 or outer lead frame section 13 for each electronic component mounting board 10, for example. This makes it possible to easily replace defective products when a plurality of electronic component mounting boards 10 are configured as a series (for example, four in a row).

[Brief explanation of the drawing]

FIG. 1 is a diagram 2 of an electronic component package showing a first embodiment of an electronic component mounting board employing a connection structure according to the present invention.
FIG. 2 is a sectional view taken along line 1-1 of FIG.

FIG. 2 is a plan view of the electronic component mounting board shown in FIG. 1;

FIG. 3 is a partial cross-sectional view of an electronic component mounting board according to a second embodiment of the present invention.

[Explanation of symbols]

10　Substrate for mounting electronic components 13 Outer lead frame part 14 Pad part 15 Outer lead 16 Solder 20 Electronic parts 30 Electronic component package

Claims (1)

[Claims] 1. A connection structure for connecting an outer lead formed separately from an electronic component mounting board having a plurality of conductor circuit layers to a pad portion on each conductor circuit layer side. The pad portions of each of the conductor circuit layers are alternately positioned in each layer, and the connection portion of each outer lead is bent to correspond to each pad portion of each of the conductor circuit layers, An outer lead connection structure characterized in that each of these connection parts and each of the pad parts are connected by solder.