JP2549996B2 - Lead frame and method of manufacturing integrated circuit package using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has an integrated circuit mounted thereon,
A lead frame used in an integrated circuit package mounted on a printed circuit board or the like, using a lead frame and which in particular comprises a dummy lead for absorbing residual brazing material
The present invention relates to a method of manufacturing an integrated circuit package .

[0002]

In Japanese Patent Publication No. 62-56665, a lead frame formed by arranging a plurality of leads as external connection terminals is provided with dummy leads for absorbing excess brazing material, and an integrated circuit is mounted thereon. There is disclosed an integrated circuit package in which a lead frame is brazed to a conductor pattern formed on a package base for cutting the dummy frame and the dummy lead absorbing the excess brazing material is cut off.

In this conventional integrated circuit package, as shown in FIGS. 6 and 7, a plurality of conductor patterns 1 for brazing a plurality of leads 101 to a package substrate 100.
Forming 02. The lead frame 103 formed corresponding to each of the conductor patterns 102 has a lead tie bar 104 that connects the plurality of leads 101, and is arranged via a brazing material 105 formed in a square ring shape. Here, dummy leads 106 for absorbing excess brazing material are formed on both outer sides of the lead 101 row of the lead frame 103.

[0004]

However, in the conventional integrated circuit package having the above structure, the package substrate 100 is used.
Excess brazing filler metal from the core flows along the dummy leads 106 to the lead tie bar 104, and then the lead tie bar 104
And flow into the lead 101 or the dummy lead 1
There is a risk that it may flow directly into the lead 101 from 06.

As described above, when the excess brazing material flows into the leads 101, the excess brazing material adheres to the leads 1
01 is caused by stains, or the thickness of the excess brazing material causes bending of the leads 101 using a jig in the process of completing the integrated circuit package, and cutting of the lead tie bar 104 for separating each lead 101. , The accurate dimensional accuracy cannot be obtained, and each lead 101
There was a problem that was not uniform.

An object of the present invention is to provide a lead frame capable of preventing excess brazing filler metal from flowing along dummy leads and lead tie bars into the leads. Also,
An object of the present invention is to provide a lead frame capable of preventing a dummy lead from directly flowing into the lead. And to provide a lead frame that prevents the formation of a bridge between adjacent leads to prevent the occurrence of a short circuit, suppresses the occurrence of stains on the leads, and easily obtains leads with accurate dimensional accuracy. is there. Furthermore, such lead frame
By making an integrated circuit package using
Prevent the formation of bridges between the leads to prevent short circuits.
Both the preventing the occurrence, suppressing the occurrence of stains on the lead, and
An integrated circuit package that can easily obtain leads with accurate dimensional accuracy.
It is to provide a method for manufacturing a cage.

[0007]

According to a first aspect of the present invention, there is provided a lead row having a plurality of leads as external connection terminals, a dummy lead for absorbing an excess brazing material, and the lead mutual. And a lead tie bar connecting the lead row and the dummy lead, wherein the dummy lead has at least one wide portion having a width wider than other portions in the vicinity, and a width wider than the wide portion. The technical means consisting of at least one narrow portion is adopted.

According to a second aspect of the present invention, in addition to the lead frame according to the first aspect, the width of the wide portion of the dummy lead is twice the width of the narrow portion adjacent to the wide portion. The above technical means was adopted. The width of the narrow portion may be substantially the same as the lead width of the lead.

According to a third aspect of the present invention, in addition to the lead frame according to the first or second aspect, a technical means in which the wide portion is provided at the tip portion of the dummy lead is adopted.

The invention described in claim 4 employs a technical means in which, in addition to the lead frame described in claim 3, the wide portion is provided also in a substantially middle portion of the dummy lead.

According to a fifth aspect of the present invention, in addition to the lead frame according to the third or fourth aspect, two of the sides forming the outer shape of the tip portion of the dummy lead are connected to the lead frame. The technical means formed so as to match the outer side of the package base to be brazed.

According to a sixth aspect of the invention, there is provided the above-mentioned lead frame.
It is a method of manufacturing an integrated circuit package using a film . Immediately
A lead that is used as an external connection terminal.
Row and dummy leads for absorbing excess brazing material
At least 1 or more, which is wider than other nearby parts
The upper wide part and at least one or more narrower than the wide part
The dummy lead consisting of the narrow part and the lead
And a lead tie connecting the lead row and the dummy lead.
A lead frame with a bar and
Molded into a predetermined shape on a package base with turns
The process of placing the brazing filler metal through the brazing filler metal and heating the brazing filler metal
Melt the tip of the lead row and the conductor pattern.
While brazing, remove the excess brazing material from the dummy tie bar.
Flow of brazing material to the lead tie bar due to the narrow portion of
And a step of absorbing into the wide portion while preventing entrapment
A method for manufacturing an integrated circuit package.

The invention according to claim 7 is the integrated structure of claim 6.
In addition to the method of manufacturing a circuit package, the dummy lead
Of using a lead frame whose front end is the wide portion
Adopted surgical means.

The invention according to claim 8 is the invention according to claim 7.
In addition to the method for manufacturing an integrated circuit package of
As a frame, on the side that forms the outline of the package base
Form the outer shape of the tip of the dummy lead so that they match.
Using a lead frame with two sides formed,
The dummy frame so that the two sides of the dummy lead are
The outer edge of the base
The technical means of mounting is adopted.

[0015]

According to the first aspect of the present invention, when brazing a plurality of leads as external connection terminals, the surplus brazing material that has been left over for brazing the plurality of leads flows into the dummy leads. The excess brazing material that has flowed into the dummy lead flows into the wide portion more than the narrow portion, and the excess brazing material from the wide portion to the narrow portion is blocked. As a result, the surplus brazing material does not flow into the lead tie bar along the dummy leads.

According to the second aspect of the invention, the width of the wide portion of the dummy lead is 2 times the width of the narrow portion adjacent to the wide portion.
Since it is doubled or more, the performance that the surplus brazing material is sucked into the wide portion rather than the narrow portion and the performance of suppressing the inflow of the surplus brazing material from the wide portion to the narrow portion become more remarkable.

According to the third aspect of the invention, the surplus brazing material is attracted to the wide portion of the tip of the dummy lead.
Since the width of the narrow portion is narrower than that of the wide portion of the tip portion and it is difficult to flow, most of the surplus brazing material that has flowed into the wide portion of the tip portion is blocked by the wide portion of the tip portion, There is no excess brazing material that flows over the narrow portion and the lead tie bar beyond the wide portion of the tip portion and flows into the lead.

According to the fourth aspect of the invention, the surplus brazing material is attracted to the wide portion at the tip of the dummy lead.
Since the narrow portion is narrower or more difficult to flow than the wide portion of the tip portion, most of the surplus brazing material that has flowed into the wide portion of the tip portion is blocked by the wide portion of the tip portion.
Nevertheless, when the surplus brazing material exceeds the wide portion at the tip portion, it passes through the narrow portion and is attracted to the next wide portion at the substantially middle portion to be dammed. As a result, there is no excess brazing material that flows along the lead tie bar over the wide portion of the substantially middle portion and flows into the lead.

According to the fifth aspect of the invention , two of the sides forming the outer shape of the tip of the dummy lead are packaged.
It is easy to align the tip of the dummy lead with the package board by matching the edges that form the outer shape of the board.
Can be done .

According to the invention described in claim 6, the melted
The brazing material penetrates between the conductor pattern and the leads,
When brazing, excess brazing material flows to the dummy leads.
It is also sucked into the wide part. This allows
Burst due to brazing material between adjacent leads due to excess brazing material
Is prevented. On the other hand, since there is a narrow part,
The surplus brazing material that was drawn in was blocked by a dummy and
Can flow into the lead via the lead tie bar.
Disappear.

According to the invention of claim 7, the surplus wax
The material is attracted to the wide part at the tip of the dummy lead.
This allows the brazing between the adjacent leads due to the excess brazing material.
The bridge by material is prevented. On the other hand, there is a narrow part
The excess brazing material sucked into the wide part of the tip is dammed.
The dummy lead and lead tie bar.
It will not flow into the card.

According to the invention described in claim 8, the dummy memory
Two sides of the tip of the card and the side that forms the outline of the package base
If you position the lead frame so that
It is also possible to position the row of columns.

[0023]

According to the invention described in claims 1 to 5, since the dummy lead is provided with the wide portion for sucking the excess brazing material and the narrow portion where the excess brazing material is hard to flow, the dummy lead is provided. Since the surplus brazing material that has flowed in is blocked by the wide portion, it is possible to prevent the surplus brazing material that has flowed into the dummy leads from flowing through the dummy leads and the lead tie bars to the leads.

Therefore, since the surplus brazing material is attracted to the wide portion of the dummy lead, the surplus brazing material is provided adjacently.
It is possible to prevent the occurrence of a short circuit due to the formation of a bridge between the two leads, and it is possible to suppress the occurrence of stains on the leads due to the adhesion of the excess brazing material. Further, when bending or cutting a plurality of leads, it is possible to obtain leads with accurate dimensional accuracy, and it is possible to reduce product defects of each lead. In the invention described in claim 5, it is very easy to align the tip of the dummy lead with the package base.

6. A method using these lead frames
~ 8 invention of the method for manufacturing an integrated circuit package
Melts the brazing filler metal so that the lead row and conductor pattern
It is possible to braze and the excess brazing filler metal has a wide dummy lead.
Part is absorbed into the two parts,
Do not form a brazing material bridge between the
It is possible to prevent short circuit between them. In addition, excess brazing material
Flow from dummy lead to lead through lead tie bar
Prevents stains on the lead as it will not get caught
be able to. With these, the process of brazing the lead
To reduce product defects in the plating process or plating process
it can. Also, the excess brazing material does not flow into the leads.
Allows the lead to be bent and cut without changing the lead thickness.
It is possible to obtain leads with accurate dimensions even in the machining process.
Therefore, product defects in this process can be reduced.
In particular, the invention according to claim 8 is the tip portion of the dummy lead.
So that the edges of the
By positioning the lead frame on the
And the lead rows can be easily aligned and aligned
Work can be simplified.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the lead frame of the present invention will be described with reference to FIGS. FIG. 1 shows an integrated circuit package that employs one embodiment of the present invention. Reference numeral 1 denotes an integrated circuit package (hereinafter referred to as an IC package). The IC package 1 includes a rectangular ceramic package base 2 made of multilayer ceramics, a lead frame 3 as an external connection terminal which is brazed to the package base 2, and a brazing material for brazing the package base 2 and the lead frame 3 together. 4 is provided.

The package board 2 is a circuit board,
As shown in FIG. 2, tungsten (W) or molybdenum (M
Conductive paste such as o) is screen-printed, each green sheet is laminated by thermocompression bonding, and then fired at a high temperature in a hydrogen furnace in a humidified atmosphere. Further, conductor patterns 21 as a plurality of terminals are formed on the surface of the package substrate 2 by high temperature firing. The conductor pattern 21 is plated with nickel to enable wire bonding for electrically connecting an integrated circuit (hereinafter referred to as an IC chip) to the outside and brazing of the lead frame 3. After brazing the lead frame 3, the package base 2 prevents corrosion and securely mounts and wire bonds an IC chip, and further improves the characteristics as an IC by using nickel and gold electricity. Plated.

As shown in FIG. 4, the lead frame 3 is formed by etching, and has a plurality of leads 31 arranged in a row, a plurality of dummy leads 32 protruding inward from both outer sides of the lead 31 row, and It is composed of a rectangular annular lead tie bar 33 that connects each lead 31 and each dummy lead 32.

The inner ends (tips) of the leads 31 are brazed to the conductor patterns 21 of the package base 2 corresponding to the leads 31, and the outer ends (other ends) of the leads 31 are connected via lead tie bars 33. It is connected to the dummy lead 32. Further, in the final step after mounting the IC chip, the leads 31 are separated from the connecting portions with the lead tie bars 33 in order to make the leads 31 independent.

As shown in FIG. 5, the dummy leads 32 have their inner ends (tips) brazed to the corners 22 of the package base 2, and their outer ends (other ends) via the lead tie bar 33. Is connected to each lead 31. Also,
The dummy lead 32 is formed on the corner portion 2 of the package substrate 2.
In the portion brazed to 2, the first wide portion 34 is formed as a surplus brazing material absorbing portion for absorbing the surplus brazing material. Further, between the first wide portion 34 and the outer end portion, a second brazing filler metal absorbing portion for absorbing the surplus brazing filler metal is provided.
The wide portion 35 is formed.

The first wide portion 34 is provided on the inner end portion of the dummy lead 32, and is formed in a square shape and a flat plate shape wider than the narrow portions 36 and 37. The first wide portion 34 of the dummy lead 32 on the left side of the drawing and the first wide portion 34 of the dummy lead 32 on the right side of the drawing are the first wide portion 34.
2 are located on the corner portions 22 of the package base 2 so that two sides of the outline of the package base 2 coincide with the sides of the package base 2. The first wide portion 34 of the dummy lead 32 on the left side of the drawing is formed so as to project to only one side in the left direction of the drawing from the narrow portion 36.
In addition, the first wide portion 34 of the dummy lead 32 on the right side of the drawing
Are formed so as to protrude only one side in the right direction in the drawing from the narrow portion 36.

The second wide portion 35 is provided substantially in the middle of the dummy lead 32 and has the same width and the same shape as the first wide portion 34. The second wide portion 35 of the dummy lead 32 on the left side and the right side in the drawing is formed so as to protrude from the narrow portion 37 in the left and right directions in the drawing by the same amount. The width of the first wide portion 34 and the second wide portion 35 is preferably at least twice as wide as the lead width of each lead 31 or the width of the narrow portions 38, 37 of the dummy lead 32.

The narrow portions 36 and 37 have the same width as the lead width of the leads 31 and are extended from the first and second wide portions 34 and 35 in the direction away from the corner portions 22 of the package base 2. ing. The narrow portion 36 connects the first wide portion 34 and the second wide portion 35, and is a portion of the lead tie bar 33.
It is arranged so as to incline from a direction orthogonal to the extension direction of the side, that is, incline in a direction away from the leads 31 on both outer sides of the lead 31 row. In addition, the narrow portion 37 includes one of the second wide portion 35 and the lead tie bar 33.
It connects the sides and is arranged in a direction (vertical) orthogonal to the extension direction of one side of the lead tie bar 33. Here, in this embodiment, in order to prevent wasteful use of gold in the gold plating process, the lead frame 3 is mounted on the package substrate 2
After brazing to each conductor pattern 21 of
Cut only 2.

In the lead tie bar 33, each lead 31 and each dummy lead 32 are provided in a comb shape so as to protrude inward. The brazing material 4 employs a silver brazing material having a melting point of 780 ° C. or more. In order to facilitate the handling of the brazing material 4, as shown in FIG. It is formed in a ring shape.

The operation of the IC package 1 of this embodiment is shown in FIG.
5 to FIG. The lead frame 3 is arranged on the conductor pattern 21 of the rectangular package base 2 with the brazing material 4 formed in a square ring shape. At this time, by aligning two of the sides forming the outer shape of the first wide portion 34 of each dummy lead 32 with the side forming the outer shape of the package base 2, the position of each dummy lead 32 and the package base 2 is adjusted. Matching can be easily performed.

As a result, since the lead 31 row is integrally formed via the dummy leads 32 and the lead tie bar 33, when the dummy leads 32 are aligned with the package base 2, the leads 31 and the package base are aligned. The alignment with the second conductor pattern 21 can be easily performed.

Then, a jig is used to press and hold. Thereafter, when heated to the melting point of the brazing material 4 (e.g. 800 ° C.) Ru to melt the brazing material 4, the capillary between one pattern of the inner end portion and the conductor pattern 21 nearest the lead 31 (terminal) The brazing material 4 invades due to the phenomenon. Then, the lead frame 3 is brazed integrally with the conductor pattern 21 of the package base 2 by cooling and solidifying the brazing material 4.

Here, the brazing material 4 formed in a square annular shape for easy handling becomes excessive at each corner portion 22 of the package base 2 where the inner end portion of the lead 31 is not brazed. Dummy lead 32 on 3
Therefore, the excess brazing filler metal that has become excessive at each corner portion 22 of the package base 2 flows into the first wide portion 34 of each dummy lead 32. Therefore, it is possible to prevent the excess brazing material from forming a bridge between the two leads 31 adjacent to each other and flowing toward the tip portion of the lead 31.

Further, in the dummy lead 32, the first wide portion 34, and the first wide portion 34 and the lead tie bar 33 are provided at the portion brazed to the corner portion 22 of the package base 2.
The second wide portion 35 is integrally molded between the first and second portions. Further, a narrow portion 36 is integrally formed between the first wide portion 34 and the second wide portion 35, and a narrow portion 37 is integrally formed between the second wide portion 35 and the lead tie bar 33. For this reason, most of the excess brazing filler metal attracted to the first wide width portion 34 of each dummy lead 32 is narrower in the narrow width portion 36 than in the first wide width portion 34, and the brazing filler metal does not flow easily. , Is blocked by the first wide portion 34.

However, even if the surplus brazing material exceeds the first wide portion 34, the narrow portions 36 and 37 are narrower than the second wide portion 35 and the brazing material is less likely to flow. It is sucked up to the next second wide portion 35 through the portion 36 and blocked. As a result, there is no excess brazing filler metal that flows into the narrow width portion 37 beyond the second wide width portion 35, so that the excess brazing filler metal flows into each lead 31 along the narrow width portion 37 of each dummy lead 32 and the lead tie bar 33. Can be prevented.

Then, only the dummy leads 32 are cut in order to prevent wasteful use of gold in the gold plating process.
Further, the package base 2 and the leads 31 are electroplated with nickel and gold. At this time, the surplus brazing material is
Since the first wide part 34 and the second wide part 35 prevent the dummy lead 32 and the lead tie bar 33 from flowing into the lead 31, the lead 31 due to the adhesion of the excess brazing material after the electroplating of nickel and gold is performed. It is possible to prevent the occurrence of stains on the top.

In addition, bending of the leads 31 using a jig in the process of completing the IC package 1 and each lead 31
The step of cutting the connecting portion of the lead 31 with the lead tie bar 33 for making the wires independent can be easily performed. Therefore, it is possible to obtain the lead 31 with accurate dimensional accuracy,
Product defects of each lead 31 can be reduced.

[0043]

[Modification] In this embodiment, a lead frame in which a plurality of leads and dummy leads are provided so as to project inward from two sides of the rectangular lead tie bar is used. A lead frame in which a plurality of leads and dummy leads are protruded inward from at least one side may be adopted, and a plurality of leads and dummy leads are protruded inward from a lead tie bar having a linear shape or a circular shape. A lead frame provided may be used.

The shape of the dummy lead for absorbing the excess brazing material does not have to be limited to the shape of this embodiment, and can be variously changed within the range not departing from the present invention.
Further, in this embodiment, the dummy brazing material is provided with the excess brazing filler metal absorbing portions (wide portions) at two places, but the dummy leads may be provided with one or more extra brazing filler metal absorbing portions (wide portions).

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a lead frame is brazed to a package base.

FIG. 2 is a plan view of a package board (circuit board).

FIG. 3 is a plan view of a brazing material.

FIG. 4 is a plan view of a lead frame.

FIG. 5 is a perspective view showing a main part of a lead frame brazed to a package base.

FIG. 6 is a plan view showing a state in which a conventional lead frame is brazed to a package base.

FIG. 7 is a plan view of a package base used for brazing a conventional lead frame.

[Explanation of symbols]

 1 IC Package (Integrated Circuit Package) 2 Package Base (Circuit Board) 3 Lead Frame 4 Brazing Material 21 Conductor Pattern 31 Lead 32 Dummy Lead 33 Lead Tie Bar 34 First Wide Section 35 Second Wide Section 36, 37 Narrow Section

Claims (8)

(57) [Claims] 1. A lead row formed by arranging a plurality of leads as external connection terminals, a dummy lead for absorbing excess brazing material, a lead tie bar connecting the leads to each other and the lead row to the dummy lead. In the lead frame, the dummy lead includes at least one wide portion having a width wider than other portions in the vicinity, and at least one narrow portion having a width narrower than the wide portion. Lead frame characterized by. 2. The lead frame according to claim 1, wherein the width of the wide portion of the dummy lead is twice or more the width of the narrow portion adjacent to the wide portion. flame. 3. The lead frame according to claim 1, wherein the wide portion is provided at a tip portion of the dummy lead. 4. The lead frame according to claim 3, wherein the wide portion is also provided in a substantially middle portion of the dummy lead. 5. The lead frame according to claim 3, wherein two of the sides forming the outer shape of the tip portion of the dummy lead form the outer shape of the package base to which the lead frame is brazed. A lead frame characterized by being formed so as to match the sides. 6. A plurality of rows of leads as external connection terminals are provided.
Lead wire and a dummy for absorbing excess brazing filler metal
-It is a lead and is wider than other parts in the vicinity.
At least one wide part and at least a narrower part than the wide part
The dummy lead consisting of one or more narrow portions, and the lead.
Connect each other and the lead row and the dummy lead.
A lead frame with a lead tie bar
On a package board with several conductor patterns
Step of placing through the brazing material formed into a shape, and melting the brazing material by heating,
While brazing the conductor pattern, the excess brazing material,
The lead tie is formed by the narrow portion of the dummy tie bar.
Absorbs in the wide part while preventing brazing material from flowing into the bar
And a method of manufacturing an integrated circuit package. 7. The wide portion has a tip portion of the dummy lead.
A lead frame that is
7. The method for manufacturing the integrated circuit package according to item 6. 8. The package as the lead frame
The dummy base so that it matches the outside edges of the base
Two of the sides that form the outer shape of the tip of the cord are formed.
Using a frame Align the lead frame with the dummy leads on the two sides.
Positioned to match the outer edge of the package base
The stacking time according to claim 7, wherein
Method of manufacturing road packages.