JPH0712066B2 - Highly reliable sealing structure and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super-large-sized computer having a sealing structure, and in particular, it eliminates defects in a solder sealing portion and has a highly reliable sealing with a dense solder layer. TECHNICAL FIELD The present invention relates to a stop structure and a manufacturing method thereof.

[Conventional technology]

The conventional apparatus is a sealing structure method of a housing having a cold water passage in a ceramic multilayer plate as described in U.S. Pat. No. 4,081,825, and a sealing portion is a mechanical crimping method using a metal gasket.

The problem with this method is that it is mechanically pressure-bonded and sealed, and during long-term use, the ceramic multi-layer board will experience fatigue damage and the metal gasket will loosen, resulting in leaks inside and outside the seal. There are many operational problems, such as a large impact on the deterioration of internal semiconductor element characteristics and, in some cases, frequent repairs and inspections of sealing parts and replacement of parts every short operating period, resulting in long-term high reliability. It was a structure that can not be.

For this reason, various structural improvements are required, and as a method for sealing the housing to the ceramic multilayer board, there is a solder-sealing structure orientation using Sn-Pb-based eutectic solder (Nikkei Electronics, Nikkei McGraw-Hill, 3- 26: 155, 1984).
However, if some of the semiconductor elements mounted on the ceramic multilayer board require disconnection due to characteristic deterioration or circuit change, the sealing part will of course also be heated and melted and re-connected due to disconnection. The sealing is repeated.

[Problems to be solved by the invention]

The above-mentioned prior art is a mechanical pressure-bonding sealing structure, and is not considered in terms of durability of the ceramic multilayer plate against pressure bonding force, and deterioration of semiconductor element characteristics inside the sealing due to fatigue breakdown of the ceramic multilayer plate, etc. There was a problem. In addition, in the solder sealing structure, no consideration is given to the defect elimination due to the repeated sealing of the solder sealing portion, which is involved in the disconnection of the semiconductor element inside the sealing, and the reliability of the solder sealing portion may be reduced. There was a problem such as deterioration of semiconductor element characteristics due to leakage inside and outside the encapsulation.

An object of the present invention is to eliminate defects in the solder sealing portion of a semiconductor device and provide a highly reliable solder sealing structure and a method for manufacturing the same.

[Means for solving problems]

Briefly explaining the present invention, the first invention of the present invention relates to a highly reliable sealing structure, which is a housing seal having a structure in which a plurality of semiconductor elements mounted on a multilayer wiring board are radiated and cooled from the back surface. In the sealing structure in which the stopper is solder-sealed to the multilayer wiring board, the solder portion of the sealing portion facing the external region where the semiconductor element is not mounted has a solder coagulation structure that is denser than the inside. And

A second invention of the present invention is an invention relating to a method of manufacturing a highly reliable sealing structure, wherein no semiconductor element is mounted in the method of manufacturing the highly reliable sealing structure of the first invention. It is characterized in that the solder portion of the sealing portion facing the outer region is remelted and then rapidly solidified to form a solder solidification structure which is denser than the inside.

The purpose is to prevent the solder-sealed solder layer portion of the semiconductor device from damaging the semiconductor element bonding structure inside the encapsulation, and not to melt the entire area of the encapsulating solder layer, that is, inside and outside the encapsulation. From the sealing outer side of the sealing solder layer, for example, CW-YAG laser light which is a radiant energy beam (output: 100 W, irradiation beam diameter:
It is achieved by irradiating (φ3.0 mm) to heat and melt, scanning the irradiation beam (speed: 10 mm / sec), and instantaneously solidifying.

In a solder sealing structure of a semiconductor device, a sealing solder layer having defects such as voids and micro blow holes that are repeatedly sealed due to disconnection of a semiconductor element is radiant energy emitted from the outside of the sealing. The beam partially heats, re-melts inward from the outer solder fillet portion, and the beam is scanned to rapidly solidify. In this case, the defects are removed during remelting with partial heating.

The heating by irradiation of the radiant energy beam is from the fired surface of the sealing solder layer portion, and the remelted portion by partial heating does not lose the heating source due to the movement of the beam, and the ceramic multilayer plate and the sealing housing are Due to heat capacity, it is rapidly solidified. The rapidly solidified solder layer portion is structurally dense. Therefore, the solder sealing portion is a double solder layer having a denser solder structure on the sealing outer side than on the sealing inner side.

In general, it is said that the fine solder structure is highly reliable in the thermal fatigue life of the soldered joint and excellent in the corrosion resistance. As a result, in the solder sealing portion of the semiconductor device, defects are eliminated during repeated sealing, and at the same time, the solder structure is densified and a highly reliable sealing structure is obtained.

The ceramic multi-layered board of the large-sized computer and the solder sealing part of the cooling housing are essential structures for protecting the most important part of the LSI device mounting part and for heat cooling from the top of the device. Therefore, it is necessary to improve the connection reliability of the solder-sealed portion in order to keep the LSI device characteristics highly reliable.

In order to improve the thermal fatigue resistance of the solder encapsulation part, the solder encapsulation part must be free from defects such as voids due to thermal fatigue failure, ensure a sufficient amount of solder that can withstand thermal fatigue, and ensure that the solder layer itself is It is about extending the service life.

In the present invention, the structure of the outer region of the solder portion is densified. The solder portion may be in horizontal contact with the housing or may be beveled to widen the outer area.

Examples of the composition of this solder include a binary alloy composed of Sn-based and Pb-based, and a multi-component solder alloy composed of a plurality of elements.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Embodiment 1 One embodiment of the present invention will be described with reference to FIGS.

FIG. 1-1 is a cross-sectional view of an example of a highly reliable sealing structure for a semiconductor device according to the present invention, and FIG. 1-2 is an enlarged cross-sectional view of a solder sealing portion thereof.

In FIGS. 1-1 and 1-2, reference numeral 1 is a multilayer substrate, 1a is a thick film metallization, 2 is an input / output pin, 3 is a semiconductor element, and 4 is a semiconductor element.
Is CCB solder, 5 is chip carrier, 6 is eutectic solder,
7 is an upper comb tooth, 8 is a lower comb tooth, 9 is a housing, 10 is a low temperature solder, and 11 is a microstructure solder.

2 and 3 are explanations of the irradiation method of the radiant energy beam. Reference numerals 9 to 11 are synonymous with those in FIG. 1, 9a is a thin film metallized, 12 is a laser beam irradiation arrow diagram, 12a is an irradiation spot, 1
2b and 12c mean spot scanning direction arrows.

FIG. 4 is a vertical cross-sectional view of the solder-sealed portion according to the conventional method,
Reference numerals 1, 1a, 9, 9a and 10 are as described above, and 13
Means a void defect.

FIG. 5 is an explanatory diagram of thermal fatigue resistance, where the horizontal axis represents Nf (lifetime) and the vertical axis represents strain amount.

As shown in FIG. 1, a chip carrier 5 and CCB solder are provided on the ceramic multilayer board 1 having the input / output pins 2 on the back side, and the upper comb teeth 7 for radiating and transmitting heat are attached to the back surface to enable the disconnection. The semiconductor element 3 connected by 4 is mounted with the eutectic solder 6, and in order to cool the heat generation of the semiconductor element and the like and to maintain the characteristics of the element and improve reliability, the entire element mounting portion is covered with the housing 9 (for example, MoCu Alternatively, AlN) is used to solder-seal the multilayer substrate 1. In this case, the chip carrier 5
The semiconductor element 3 is connected to the CCB solder 4 of Pb-5% Sn,
Mounting on the substrate is Pb-60% Sn (melting point: liquid phase 190 ° C, solid phase
183 ° C) eutectic solder 6. Therefore, the board sealing solder material of the housing must be sealed with a solder lower than the melting point (solid phase 183 ° C) of the eutectic solder so as not to damage the mounting part by remelting. There is. Therefore, in the present invention, low temperature solder, such as Pb45%, Bi18
%, Solder consisting of residual Sn (melting point: liquid phase 160 ° C, solid phase 136
(° C).

When encapsulating, a solder layer is formed in advance using a rosin-based flux on the encapsulation part of the Ni-Au plated metallized housing, and the encapsulation part of one ceramic multilayer plate (for example, W-Ni thick film metallization). In 1a), only the amount of soldering layer necessary for connection was formed.

After thoroughly removing and cleaning the flux, the housing is aligned on the ceramic multilayer board, and each solder is heated and melted (maximum temperature 180 ° C) in an atmosphere furnace (for example, He or N ₂ gas atmosphere). Joined and sealed.

Generally, in the soldered part where the joint area is large,
As shown in the cross-sectional view of the solder-sealed portion in FIG. 4, a void defect 13 such as a gas void or a micro blow hole is caused by a wetting reaction gas between the solder 10 and the metallization 1a, 9a or a gas generated by heating from the metallization itself. Occurs and is easily formed in the solder layer.

FIG. 2 and FIG. 3 are explanatory views for eliminating void defects in the solder layer portion sealed by solder and forming a dense solder texture layer.

In FIG. 2, a radiant energy beam (for example, CW-YAG laser light, output: about 100 W, irradiation beam spot diameter: about) from the outside of the low temperature solder layer 10 in which the housing 9 is sealed on the ceramic multilayer plate 1 (φ3.0 mm), the partial remelting of the solder layer is started from the outer side to the inner side of the sealing solder cross-sectional layer as shown in the figure. In this case, if the entire area of the solder layer is remelted, the atmosphere inside the sealing leaks to the outside, which is not preferable from the viewpoint of maintaining the semiconductor element characteristics. Therefore, the solder layer area to be remelted and solidified is preferably 1/3 to 1/2 of the solder sealing width.
The heating and melting width can be controlled by the irradiation time of the beam, the output, and the like. Further, the solidification takes a solidification form when the irradiation of the beam is stopped or the irradiation position is moved, because the heat source for heating and melting is not supplied. Partial heating and melting by the energy beam is characterized in that it can be instantly started because the beam is a high heat source with high output. vice versa,
When the irradiation of the energy beam is stopped, the partial melted portion is instantaneously, that is, rapidly cooled and solidified by heat absorption (due to heat transfer) from the unmelted portion.

Therefore, the remelted and solidified solder layer becomes a denser solder layer (crystal size: about 1 to 3 μm / piece) than the crystal size (about 10 to 15 μm / piece) of the unmelted portion. Therefore, as shown in FIG. 3, when the solder seal portion of the housing and the ceramic multilayer board has a relatively long dimension, the irradiation beam is scanned along the solder seal portion (in the case of the previous term, the scanning speed is 5 ~
15 mm / sec) or by moving the sealing structure, the cross-sectional structure of FIG. 1-2 can be obtained.

Further, in the sealing structure as shown in FIG. 3, by simultaneously scanning the beam irradiation spots as shown in FIGS. 12b and 12c, the thermal stress to the sealing structure can be eliminated and the efficiency is high.

FIG. 5 shows the highly reliable sealing structure obtained by the present invention (see 1-1
(Fig.) Is an explanatory view of the thermal fatigue resistance property.

The heat-resisting fatigue characteristics of the solder encapsulation part when the radioactive energy beam is irradiated and the dense solder texture layer is formed (FIG. 5A) and when it is not formed (FIG. 5B) are The reliability was improved about 10 times more than the case without one. Furthermore, the structure in which the dense solder layer portion is formed has several stages of improvement in corrosion resistance as compared with the structure in which it is not formed.

Example 2 An example of the sealing portion of the structure of the present invention is shown in FIG. That is, FIG. 6 is an enlarged sectional view of a solder sealing portion in another example of the present invention. In FIG. 6, reference numerals 1, 1a, 9, 9a,
10 and 11 are as described above, and 9b means a housing sealing portion. As shown in FIG. 6, first, an inclined portion is added to the sealing portion 9b of the cooling housing to perform solder sealing. Since the structure of the housing is inclined, the generated gas at the time of solder sealing escapes to the outside of the sealing, so that the defects in the solder sealing layer are reduced. Also, with this structure, the gap between the sealing part and the ceramic multi-layer substrate is increased to the outside of the sealing,
Therefore, a sufficient amount of sealing solder can be secured.

In addition, the large solder surface on the outside of the encapsulation makes it easy to irradiate a radiant energy beam to guide the encapsulation solder layer with high reliability and to supply a large amount of heat. Therefore, instantaneous remelting / solidification is possible. Can be performed up to the vicinity of the inside of the encapsulation, a large number of dense solder layers can be formed, and the reliability can be further improved.

〔The invention's effect〕

According to the present invention, defects in the solder sealing portion can be easily eliminated, and a dense solder layer can be formed. Therefore, there is an effect that it is possible to manufacture a semiconductor device having a highly reliable sealed structure which is excellent in heat fatigue resistance and corrosion resistance.

[Brief description of drawings]

FIG. 1-1 is a vertical sectional view of a solder sealing structure according to an embodiment of the present invention, and FIG. 1-2 is a partially enlarged sectional view thereof, FIG. 2 and FIG.
The figure is an illustration of irradiation method of radiant energy beam, 4th
FIG. 5 is a vertical sectional view of a solder sealing portion by a conventional method, FIG. 5 is an explanatory view of thermal fatigue resistance characteristics, and FIG. 6 is an enlarged sectional view of a solder sealing portion in another example of the present invention. 1: Multilayer substrate, 1a: Thick film metallization, 2: Input / output pin, 3: Semiconductor, 4: CCB solder, 5: Chip carrier, 6: Eutectic solder, 7: Upper comb tooth, 8: Lower comb tooth, 9: Housing, 9a: Thin film metallization, 9b: Housing sealing part, 10: Low temperature solder, 1
1: Microstructure solder, 12: Laser light irradiation arrow diagram, 12a: Irradiation spot, 12a and 12b: Irradiation spot scanning direction arrow diagram, 13: Void defect

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Sawahata 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitori Works, Hitachi Research Laboratory (72) Inventor Mitsuru Shirai 1 Horiyamashita, Hadano City, Kanagawa Prefecture Nitate Works Co., Ltd. Kanagawa Plant (72) Inventor Shinichi Wai 1 Horiyamashita, Hadano City, Kanagawa Prefecture Hiritsu Manufacturing Co., Ltd. Kanagawa Plant (56) Reference JP 62-264697 (JP, A) JP 61-258456 (JP JP, A)

Claims (4)

[Claims] 1. A semiconductor device is mounted in a sealing structure in which a housing sealing portion for radiating and cooling from the back surface of a plurality of semiconductor elements mounted on a multilayer wiring board is solder-sealed to the multilayer wiring board. The highly reliable sealing structure, wherein the solder portion of the sealing portion facing the external area is a solder solidification structure that is denser than the inside. 2. The high reliability according to claim 1, wherein the solder composition of the sealing portion is a binary alloy composed of Sn-based or Pb-based or a multi-component solder alloy composed of a plurality of elements. Encapsulation structure. 3. A method of manufacturing a sealing structure in which a housing sealing portion having a structure for radiating and cooling from the back surface of a plurality of semiconductor elements mounted on a multilayer wiring board is solder-sealed to the multilayer wiring board, A highly reliable encapsulation characterized by remelting the solder portion of the sealing portion facing the outer area where no semiconductor element is mounted and then rapidly solidifying it to form a solder solidification structure that is denser than the inside. Structure manufacturing method. 4. The method for producing a highly reliable sealing structure according to claim 3, wherein a radiant energy beam is used as a heat source for forming the solder solidification structure.