JPH09260523A - Manufacture of ic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To see that seal trouble may not occur at a seal part by brazing filler metal. SOLUTION: A package assembly is set in the product housing recess 22 of a brazing jig 21, and also a heat accumulating block 25 made of graphite is accommodated in the cavity of each package assembly. For the package assembly, a band-shaped Ag brazing filler matal is inserted at the junction part between a metallic base 11 and a metallic ring 12 or at the seal part of the inner brim of a board insertion part 14 or the like. Holes 23 for reducing the quantity of accumulated heat are made at the four places around the product accommodation recess 22 of the brazing jig 21. A cover 24 made of graphite is put on the top of this brazing jig 21, and it is carried to a brazing furnace by a conveyor, and Ag brazing filler metal is fused and solidified, thus the sealing of the inner brim of the board insertion port 14 and the joining between the metallic base 11 and the metallic ring 12 and others are performed at the same time. Hereby, favorable meniscus without a recess of brazing material is made outside the seal part of the metallic case 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inserts a ceramic substrate into a substrate insertion opening formed on a side surface of a metal case,
The present invention relates to a method for manufacturing an IC package in which the seal portion is sealed with a brazing material.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, an IC package used as an optical transmission component for optical communication is Cu /
Ag of Kovar metal ring 12 on W metal base 11
A metal case 13 is formed by brazing with a brazing material, and an alumina ceramic substrate 15 is inserted through a substrate insertion port 14 formed on the side surface of the metal case 13. A conductor pattern 16 made of W, Mo or the like is formed on the ceramic substrate 15, and a lead frame 17 is joined to the conductor pattern 16 with an Ag brazing material. The space between the ceramic substrate 15 and the peripheral edge of the substrate insertion port 14 is hermetically sealed with an Ag brazing material.

Conventionally, a seal of the inner peripheral edge of the substrate insertion port 14 and the lead frame 17 are joined by Ag brazing material,
The metal base 11 and the metal ring 12 are joined at the same time as follows. First, the package assembly (IC package before brazing) on the brazing jig
Is set. Here, the package assembly includes a joint portion between the metal base 11 and the metal ring 12 and a board insertion opening portion 14.
A band-shaped Ag brazing material is sandwiched between the seal portion at the inner peripheral edge and the joint portion between the conductor pattern 16 and the lead frame 17 and assembled. This package assembly is placed on a brazing jig and passed through a brazing furnace to melt and solidify the Ag brazing material at each part, to seal the inner peripheral edge of the board insertion port 14, the lead frame 17, and the metal base. 11 and the metal ring 12 are joined at the same time.

The brazing jig used at this time is generally made of graphite (carbon) which is easy to cut, and the package assembly is housed in the product housing recess formed in the brazing jig. It is designed to pass through a brazing furnace. In addition, the inside of the brazing furnace is controlled at around 800 ° C to melt the Ag brazing material, and to prevent combustion of the graphite brazing jig and to prevent metal oxidation. Hydrogen and nitrogen gas are flowed inside.

[0005]

In the above-described conventional brazing method, the Ag brazing material may be dented in a part of the seal portion at the inner peripheral edge of the substrate insertion opening 14 to cause incomplete sealing. This was one of the causes of the leak. Here, the cause of the depression of the Ag brazing material is that the metal case 1 is formed when the Ag brazing material is cooled and solidified after the melting.
It is considered that there is a temperature difference between the inside and the outside of No. 3 and the solidification speed of the Ag brazing material is different. That is, the metal case 1
Since the inside of 3 is a cavity, it is exposed to the flow of gas in the brazing furnace, and heat dissipation is promoted to lower the temperature relatively quickly, while the outside of the metal case 13 is brazed. Surrounded by a tool (graphite), its heat storage slows down the temperature. Therefore, the solidification of the Ag brazing material progresses from the inside of the metal case 13, and the slower solidifying outer melting brazing material is attracted to the faster solidifying inner Ag brazing material. Occasionally, a dent may occur and the seal may be incomplete.

The present invention has been made in consideration of the above circumstances, and therefore an object thereof is to prevent a defective seal (leak) from being generated in a seal portion made of a brazing material.
An object of the present invention is to provide a method of manufacturing an IC package that can improve the yield.

[0007]

In order to achieve the above object, a method of manufacturing an IC package according to the present invention is a package assembly in which a ceramic substrate is inserted through a substrate insertion opening formed on a side surface of a metal case. The heat storage block made of graphite is set in the cavity of the above, and the brazing jig on which the package assembly is placed is covered with the graphite lid, and is passed through the brazing furnace to insert the substrate of the metal case. An IC package is manufactured by sealing the sealing portion between the periphery of the mouth and the ceramic substrate with a brazing material (claim 1).

As described above, the cause of the depression of the brazing material in the seal portion around the board insertion port is the temperature difference between the inside and outside of the metal case, and the cause of this temperature difference is
This is because the cavity of the metal case is exposed to the gas flow in the brazing furnace to promote heat dissipation.

Therefore, in the present invention, the graphite heat storage block is set in the cavity of the metal case, and the brazing jig is passed through the brazing furnace with the graphite lid being covered. This prevents the gas from hitting the package assembly directly, and slows down the temperature drop inside the metal case due to the heat storage of the graphite heat storage block housed in the cavity of the metal case, and the temperature difference inside and outside the metal case. To reduce. In this case, both the lid and the heat storage block are made of graphite, but this is because of ease of processing and heat storage.

When the brazing jig is made of graphite as in claim 2, the vicinity of the seal portion around the board insertion opening of the metal case is provided around the product storage recess of the brazing jig. It is preferable to form a hole for reducing the heat storage amount. In other words, graphite has a relatively large specific heat and a large amount of heat storage, so by forming a hole around the product storage recess, the amount of heat storage near the seal on the outside of the metal case is reduced, and the seal of the metal case is reduced. The temperature of the outside of the portion is lowered a little faster than that of the inside, whereby the Ag brazing material of the seal portion is solidified from the outside, and a good meniscus of the brazing material is formed on the outside.

The brazing jig may be
It may be made of a metal or ceramic having a specific heat of 0.20 cal / g · deg or less. In this case, claim 2
Since the amount of heat storage around the product storage recess is smaller than that of the graphite brazing jig described in 1 above, the difference in the amount of heat storage inside and outside the metal case can be reduced without forming a hole as in claim 2. can do.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The structure of the IC package (package assembly) to be manufactured is the same as the conventional one (see FIG. 4), and since this has already been described, the description is omitted.

The brazing jig 21 is formed by cutting graphite. The brazing jig 21 is formed with a plurality of product storage recesses 22 for storing a plurality of package assemblies.
Holes 23 are formed at four locations around the. Each hole 23 is in contact with or close to the metal base 11 and the ceramic substrate 15 of the package assembly housed in the product storage recess 22, has an inner diameter of 2 to 20 mm, and has a depth of the depth of the product storage recess 22. That is all.

When each part of the package assembly is brazed by using the brazing jig 21, the package assembly is placed in each product accommodating recess 22 of the brazing jig 21 as shown in FIG. While being set, the heat storage block 25 made of graphite, which is slightly smaller than the cavity, is provided in the cavity of the metal base 11 of each package assembly.
To store. In each package assembly, a band-shaped Ag brazing material is sandwiched between the joint portion of the metal base 11 and the metal ring 12, the seal portion of the inner peripheral edge of the substrate insertion opening portion 14, and the joint portion of the conductor pattern 16 and the lead frame 17. Has been.

Then, the upper surface of the brazing jig 21 is covered with a graphite lid 24, and it is conveyed to a brazing furnace by a conveyor. The inside of the brazing furnace is controlled at around 800 ° C. in order to melt the Ag brazing material, and further, to prevent the graphite brazing jig 21 and the lid 24 from burning and to prevent the metal from oxidizing. Hydrogen and nitrogen gas are flowed in the furnace. When passing through the brazing furnace, the package assembly on the brazing jig 21 is heated by heat transfer and heat radiation (radiant heat) from the brazing jig 21 and the lid 24. As a result, the Ag brazing material is heated to a temperature higher than the melting temperature and melted, and the Ag brazing material is solidified.
4. Sealing of the inner peripheral edge, joining of the lead frame 17, and joining of the metal base 11 and the metal ring 12 are simultaneously performed.

FIG. 5 shows part A (the front end part in the traveling direction at the outer end of the ceramic substrate 15) when the brazing jig 21 is conveyed in its longitudinal direction (longitudinal direction of the package assembly) and passed through the brazing furnace. ) And a temperature profile of the B portion (the rear end in the traveling direction at the inner end of the ceramic substrate 15) in the brazing process, and (a) is the temperature change without the lid (corresponding to the conventional example). Yes, (b) is a temperature change when the upper surface of the brazing jig 21 is covered with a graphite lid 24.

In the case without the lid, since the gas in the brazing furnace directly hits the package assembly, the temperature difference before and after the traveling direction of the package assembly becomes large, and the temperature difference between the parts A and B is large. Can reach 8 ° C.

On the other hand, when the upper surface of the brazing jig 21 is covered with a graphite lid 24, the lid 24 blocks the gas in the brazing furnace from directly hitting the package assembly, and the package assembly is blocked. The solid body radiates heat through the brazing jig 21 and the lid 24. As a result, the temperature difference before and after the moving direction of the package assembly is reduced,
The temperature difference between section B and section B is 5 ° C.

Further, in the above embodiment, the metal case 13 is used.
Material with a large specific heat (graphite) inside the cavity
Since the heat storage block 25 formed in 1 is set, the temperature decrease inside the metal case 13 can be delayed by the heat storage of the heat storage block 25, and the solidification of the Ag brazing material is biased toward the inside of the metal case 13. Can be prevented.

Moreover, since the holes 23 are formed at four locations around the product storage concave portion 22 of the brazing jig 21, the amount of heat stored near the seal portion outside the metal case 13 can be reduced, and the lid 24 and the heat storage described above can be reduced. In combination with the effect of the block 25, the temperature of the outside of the seal portion of the metal case 13 can be lowered a little faster than that of the inside. As a result, the Ag brazing material in the seal portion can be solidified from the outside a little faster, and a good meniscus of the Ag brazing material can be formed on the outside.

The inventor of the present invention has made the lid 24, the heat storage block 25,
In order to evaluate the effect of the hole portion 23, the following three kinds of brazing methods were tested, the quality of the meniscus of the Ag brazing material in the seal portion was observed, and the presence or absence of leak was determined by a leak test (see The density standard is 1 × 10 ^-8 atm cc / sec).

Sample No. 1 Only the brazing jig 21 (without the hole 23) was put on the lid 24, and there was no heat storage block 25.

Sample No. 2 Cover the brazing jig 21 (without the hole 23) on the lid 24, and set the heat storage block 25 in the cavity of the metal case 13.

Sample No. 3 Cover the brazing jig 21 having the hole 23 with the lid 24,
In addition, the heat storage block 25 is provided in the cavity of the metal case 13.
Is set.

The test results are shown in Table 1 below.

[0026]

[Table 1]

When only the lid 24 is used (Sample No. 1)
The gas inside the brazing furnace does not hit the package assembly directly, but since there is no means (heat storage block 25) for storing heat inside the metal case 13, the temperature inside the metal case 13 decreases faster than the outside. The solidification of the Ag brazing material progresses from the inside of the metal case 13, and the slower solidifying outer melting brazing material is attracted to the faster solidifying inner Ag brazing material. For this reason, a recess whose bottom cannot be seen is formed in the meniscus of the Ag brazing material in the seal portion, and it is determined to be unacceptable (with a leak) even in the leak inspection.

In the case of the lid 24 + the heat storage block 25 (Sample No. 2), the temperature drop inside the metal case 13 can be delayed by the heat storage of the heat storage block 25, and the Ag brazing material is biased to the inside of the metal case 13. It is possible to prevent the coagulation of the above. In this case, Ag of the seal part
There is a dent on the meniscus of the brazing material where the bottom can be seen, but there is no problem because it is judged as pass (no leak) in the leak inspection.
Therefore, the desired object of the present invention can be achieved without forming the hole 23 in the brazing jig 21.

In the case of the lid 24 + the heat storage block 25 + the hole 23 (Sample No. 3), the hole 2 is formed in the brazing jig 21.
By forming 3, it is possible to reduce the amount of heat stored in the vicinity of the seal portion on the outer side of the metal case 13, and in combination with the effect of the lid 24 and the heat storage block 25 described above, the outer side of the seal portion of the metal case 13 is more The temperature can be lowered a little faster. As a result, the Ag brazing material in the seal portion can be solidified from the outside a little earlier to form a good meniscus without a dent on the outside of the seal portion, and the leak inspection determines that the material is acceptable (no leak).

In this case, since the brazing jig 21 is made of graphite having a large specific heat, the brazing jig 21
Although the amount of heat stored near the seal portion on the outside of the metal case 13 is reduced by forming the hole portion 23 in the metal case 13, the brazing jig is made of a material having a small specific heat, for example, a specific heat of 0.20 cal / g · deg. If it is formed of the following metal or ceramic, it is not necessary to form a hole in the brazing jig. That is, in this case, even if there is no hole in the brazing jig, the amount of heat stored in the brazing jig itself is small, so that the heat storage block 25 made of graphite having a large specific heat is stored inside the metal case 13. Then, in the above sample No.
Similar to the case of 3, it is possible to form a good meniscus on the outer side of the seal portion.

The shape of the hole 23 formed in the graphite brazing jig 21 is not limited to a circular hole, but may be a square hole, and the number of the hole 23 may be as required. It goes without saying that it may be changed as appropriate.

In addition, the present invention is not limited to an optical transmission component for optical communication, and is directed to a method of manufacturing an IC package having a structure in which a ceramic substrate is inserted into a substrate insertion opening of a metal case and sealed with Ag brazing material. Various modifications can be made without departing from the scope of the invention, such as wide application.

[0033]

As is apparent from the above description, according to the manufacturing method of claim 1 of the present invention, the graphite heat storage block is set in the cavity of the package assembly, and the package assembly is set. Because the brazing jig is brazed by covering it with a graphite lid, the temperature difference between the inside and the outside of the package assembly can be reduced, and the meniscus of the brazing filler metal in the seal part can be made better than before. It is possible to improve the quality, prevent defective sealing (leakage), and improve the yield.

Further, according to the second aspect, since the hole is formed around the product accommodating recess of the graphite brazing jig, the temperature of the outside of the seal portion of the metal case is lowered a little faster than that of the inside. As a result, a good meniscus can be formed outside the seal portion.

In the third aspect of the invention, the brazing jig is made of metal or ceramic having a specific heat of 0.20 cal / g · deg or less. As in the case of (1), it is possible to reduce the amount of heat accumulated around the product storage recess, and it is possible to form a good meniscus on the outside of the seal portion.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a state where a package assembly is set on a brazing jig with a lid according to an embodiment of the present invention.

FIG. 2 is a plan view of a brazing jig.

FIG. 3 is a partial perspective view showing a set state of a package assembly on a brazing jig.

FIG. 4 IC package to be manufactured (package assembly)
Perspective view of

5A is a temperature profile diagram of a brazing process showing a temperature difference due to a position difference of a package assembly when a brazing jig without a lid is used, and FIG. 5B is a brazing jig with a lid. Profile diagram of the brazing process showing the temperature difference depending on the position of the package assembly when the soldering tool is used

[Explanation of symbols]

11 ... Metal base, 12 ... Ring, 13 ... Metal case,
14 ... Substrate insertion port, 15 ... Ceramic substrate, 16 ... Conductor pattern, 17 ... Lead frame, 21 ... Brazing jig, 22 ... Product storage recess, 23 ... Hole, 24 ... Lid, 25
… Heat storage block.

Claims (3)

[Claims] 1. A metal case is obtained by placing a package assembly, which is assembled by inserting a ceramic substrate through a substrate insertion opening formed on a side surface of a metal case, on a brazing jig and passing it through a brazing furnace. In a method of manufacturing an IC package by sealing a sealing portion between a substrate insertion opening and a ceramic substrate with a brazing material, a graphite heat storage block is housed in a cavity of the metal case, and the brazing treatment is performed. A method for manufacturing an IC package, comprising: passing a brazing furnace with a graphite lid on the tool. 2. The brazing jig is made of graphite, and a product accommodating recess for accommodating the package assembly is formed in the brazing jig, and the metal case is provided around the product accommodating recess. 2. The method for manufacturing an IC package according to claim 1, wherein a hole is formed in the periphery of the board insertion opening for reducing the amount of accumulated heat in the vicinity of the seal. 3. The brazing jig has a specific heat of 0.20 c
The method of manufacturing an IC package according to claim 1, wherein the IC package is formed of a metal or a ceramic having an a / g · deg or less.