JPS5842622B2 - sealed container - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sealed container containing electrical components.

Sealing electrical components to prevent them from being contaminated and degraded by exposure to the atmosphere is important for many applications, and in some cases critical.

Hermetically sealing electrical components is particularly important in the field of semiconductor packaging.

Microcircuit devices of semiconductor strips are easily damaged because the circuits on such small component parts belong to □Cron, and such circuit dimensions are easily subject to short circuit or open circuit damage when exposed to the outside world. There are things to do.

In addition to damage to connected circuits, atmospheric contamination of the semiconductor material itself can significantly affect the electrical response of the material.

Certain components are often sealed and protected from the atmosphere by having a layer of glass welded over them.

Alternatively, a metal cap may be used to seal the electrical components by soldering the cap over a substrate mounted with a semiconductor strip.

These conventional methods of sealing electrical components to protect them from the outside world require that the solder or glass be heated to melting temperature, thereby subjecting the electrical device to significant thermal stress.

Hermetic sealing is necessary for many electrical applications where expensive high density semiconductor strips are used.

Such a seal has a sensitivity lXl0 'sec/sec
(This unit refers to standard cubic centimeters per second and can also be abbreviated as standard cIIL3/sec, meaning cubic centimeters at 25° C. and 1 atmospheric pressure, and is used to measure volumetric flow.

) using a helium mass spectrometer leak tester.
Allows no detectable leakage when tested according to Standard 883.

Conventional methods of creating such seals generally involve delicate and expensive processes such as noble metal soldering or welding of the sealing glass to the sealing glass itself and metal conductors.

Moreover, once the components are protected from the atmosphere by such conventional methods, they cannot be easily replaced.

On the contrary, if changes are required to the circuit, it is often necessary to manufacture an entirely new package.

It is therefore an object of the present invention to provide a sealed enclosure for electrical components that is more reliable and cheaper than conventional ones.

Another object of the invention is to provide a hermetically sealed container for electrical components that does not expose the electrical components or substrates to decadent temperatures, thus allowing the use of a wide range of component materials and substrates, including plastics. That's true.

Yet another object of the invention is to provide a sealing device that is easily removable so that the sealed component is accessible if repair or replacement of the component is desired. 0, i.e. contains electrical components,
a substrate on which the electrical component is provided, the substrate having a device for electrically connecting the electrical component, and a wall surrounding the electrical component, in a portion formed by the wall; To provide a sealed container equipped with a thermally recoverable sealing member that applies sufficient pressure to seal against a wall when the container is in the air.

and further includes an electrical component and has a sealing ring at the open end, the ring having a horizontal portion and a sloped portion such that a plane of the horizontal portion and a plane of the sloped portion form an acute angle, and the sealing ring The present invention provides a sealed container having a thermally recoverable member within a portion formed by the sealing ring that applies sufficient pressure to seal the sealing ring.

According to the invention, therefore, the electrical components are sealed with a thermally recoverable sealing member.

In the case of metal sealing members, the metal easily deforms when cooled to a humidity lower than the martensitic dislocation humidity of the metal, but is forced to return to its original shape when warmed. Become.

A metal sealing member in an unstable martensite state,
The sealing member is dimensioned to fit into a cooperating wall or sealing ring with the substrate on which the electrical component is placed, the sealing member is inserted into the area formed by the wall or the sealing ring, and the sealing member is Substantial forces are applied to the wall and sealing ring by heating it to a stable austenitic state and restoring the part to its original shape.

This force is sufficient to seal the electrical components.

Similarly, in the case of plastic seals, the plastic will return to its original shape once heated by heating the polymeric material to shape it to the proper dimensions and then rapidly cooling it to the same dimensions.

By accurately sizing the sealing members as well as the walls and sealing rings, sealing pressure can be accurately and reversibly applied to seal the electrical components.

In the case of metals, the transition to the stable austenitic state usually occurs in a room or at a relatively low temperature so that the electrical components are not exposed to heat that could cause thermal degradation.

In the case of thermally recoverable plastics, the thermal recovery is approximately 149°C (300°C), which is well below the temperature that would cause thermal degradation of the solder joint or oxidation of the conductor.
'F) or at lower temperatures.

Preferred embodiments of the invention will now be described. Thermally recoverable metals, i.e., materials whose dimensions restore from a thermally unstable state to a thermally stable state when heat is applied, are used in a wide variety of applications. has been done.

Regarding thermally restorable metallic materials, various alloys of titanium and nickel have been revealed to be easily imparted with thermal restorability due to dimensional deformation in the humidity when the metal exists in a martensitic state. There is.

Examples of such alloys are U.S. Pat. No. 3,174,851;
No. 3351463, No. 3753700 and No. 375
No. 9552.

Applications for these alloys include
U.S. Patent Application “Thermal Restoreable Metal Fittings” (Heat R
ecoverable MetallicCoupli
This includes use in fittings for conduits, such as hydraulic lines, as outlined in ``.

In conduit fittings, the thermally recoverable metal is formed into a generally cylindrical shape expanded in its unstable martensitic state and is placed over the ends of the conduits to be joined.

Once the expanded heat-restoreable metal is warmed to a stable austenitic state, it will restore to its original dimensions, thus connecting and sealing the cylindrical covered tube.

In addition to being used to connect pipes, thermally recoverable metals are disclosed in US patent application Ser.
It is also used to plug and seal tubes as outlined in ``Ansion Plug''.

The patent application outlines a round plug that fits into a hole in a pipe, drum, or tank, conventionally using a pressure-fit threaded plug.

Accordingly, conventional sealing applications of thermally recoverable metals are generally limited to connecting or sealing conduits or containers so that gas or liquid within the conduits or containers does not leak to the atmosphere.

Similarly, sealing applications for heat-restoreable plastic materials are generally limited to connecting or sealing conduits or containers so that gas or liquid within the conduits or containers will not leak to the atmosphere.

For example, in US Pat. No. 37'41,422 a heat restorable plastic material is used to seal the bottle.

Applicants are now discovering entirely new uses for these thermally restorable materials.

Thermally recoverable materials can be used in electrical component manufacturing to seal electrical components from the atmosphere as seals, and such seals are simpler than conventional sealing devices utilized in the electronics industry. and reliable.

Referring now to Figures 1 and 2 of the accompanying drawings, there are shown top plan and side views of an electronic package that can be utilized as a sealed container in accordance with the present invention.

A suitable substrate 2 is connected to the electrical components 6 shown in FIG.
It is covered with electrical connectors 4 and 6 to provide input and output image devices.

The substrate 2 is made of an inorganic insulator (ceramic, glass) or an organic insulator (epoxy, phenol, melamine, nylon,
It may be made of any insulating material, including polyester, Teflon, polyimide, and polyarylene.

When organic insulators are used as substrate materials, reinforcing agents such as glass fibers or microspheres are desirable to provide the necessary stiffness to the electronic package.

A metal coated die mounting pad 8 is utilized to receive the component 6 to be mounted and electrically connected.

For mounting the die, the pad 8 is entirely coated with a precious metal such as gold.

Similarly, the connector 4 can also have a top layer of gold;
There may be a less expensive metal such as copper underneath the same layer.

Preferably, the metal connector 4 is sputtered (Sp
It is deposited on the substrate 2 by known methods such as uttering, vapor deposition, or electroplating.

However, separate wiring may be used in the electronic package of the present invention.

Electrical connector 4 is then connected via conductor 10 to the combined second stage package.

The substrate 2 may be transformed into a multi-layered form with the conductor 10 sandwiched therebetween.

Such substrates allow for more compact packaging because multilayer circuits can be utilized.

Of course, single layer substrates can also be utilized in cases where high circuit density is not required.

As seen most clearly in FIGS. 2 and 3, the die mount on which the electrical components are to be mounted is provided with a wall 12 surrounding the pad.

This wall can be an integral part of the substrate and have the same composition as the substrate.

Since inorganic substrates such as ceramic or glass are hard, it is preferable to provide a wall having at least part of its inner surface of a fairly soft material.

Accordingly, a separate metal ring may be attached to the ceramic substrate, the ring having a portion on its inner surface that is contacted by a heat restorable member coated with a soft metal such as gold.

Of course, when wall 12 and substrate 2 are an integral part, such as ceramic, the inner wall may be coated with a soft metal such as gold.

Furthermore, when soft organic insulators are used as substrates and walls, there is no need to coat the inner surfaces of the walls with soft materials.

However, even if the inner surface of the wall is of soft material, it is still desirable to provide a sealing ring, such as the ring shown in FIG. 7, into which the sealing member can be firmly wedged. be.

After placing the electrical component 6 over the pad 8,
A thermally recoverable member 14 is placed within the wall 12 over the component 6 to seal it from the atmosphere.

Member 14 may be constructed of any material that has thermal recovery capabilities and that exerts a force when changing from a deformed unstable state to a more stable state.

For metal seals, generally +135°C to -19°C
Metals having a transition temperature within the range of 6°C are satisfactory for use in the present invention.

Preferably, the sealing member is made of 47.1% nickel, 4
Constructed from a flat disc of nickel-titanium alloy containing 9.4% titanium and 3.58% iron.

This composition results in a material with a transition temperature of about -125°C.

The disk is immersed in liquid nitrogen exhibiting a stable impregnation of =196° C., thereby lowering the temperature below the dislocation temperature of the disk.

While maintained at this reduced temperature, the disk is subjected to a force sufficient to cause a heat-recoverable plastic deformation, for example in a press, so that the disk becomes a thermally unstable rectangular shape. be done.

The deformed disk is maintained at a temperature below its transposition temperature, for example by continuous immersion in liquid nitrogen, until the disk is ready for use.

The disc is inserted in the cooled state into the area formed by the wall 12 of the container and is then left to warm up.

This method produces little, if any, thermal stress.

Obviously, the electrical component 6 is not exposed to the high temperatures to which it would be exposed in the conventional method.

Although in most cases the entire electronic package can be cooled to liquid nitrogen temperatures during the sealing operation, this is not necessary.

Alternatively, member 14 may be made of a polymeric material that can be made thermally resettable so that it exerts force when restored.

Thermally restorable materials and methods of their manufacture are well known, see for example US Pat. No. 3,415,287.

When the substrate wall or sealing ring is made from a soft deformable material, a hard non-deformable plastic is preferred to ensure that the plastic member will completely seal the electrical components.

Alternatively, the plastic sealing member may be made of a soft deformable material while the ring or wall is a hard non-deformable material.

However, this material must be selected and dimensioned to ensure that sufficient pressure is applied to the wall or ring of the container to deform the soft material at the interface and seal the electrical components. Must be.

Particularly suitable for such applications are polyarylene plastics.

This polymer has a high degree of crystallinity, even if not cross-linked, so it can be deformed at room temperature and returns to its original shape when heated, thus providing sufficient force to seal electrical components. It has sufficient elastic memory to exhibit

The shape of the sealing member 14 is such that it is in a deformed state and closes to the wall 1.
2. It must be able to fit easily into the 2.

The use of a circular wall in combination with a thermally recoverable member transformed from a flat to a flat shape is particularly suitable for this application, since the sealing pressure on the wall can be easily calculated.

The thermally recoverable member may be provided with ridges 16 to allow insertion of a retaining tool and to properly position the member within the walls of the electronic package.

Referring to FIG. 3, wall 12 is provided with a lip 18 for receiving the thermally recoverable member.

A seal is created between the thermally resettable sealing member and the wall at the surface of this lip, which surface should have a material that will deform when subjected to a force by the thermally resettable member. .

In the case of a titanium-nickel alloy seal, this lip surface should have a softer material than the titanium-nickel alloy, such as gold or plastic.

By using a contoured thermally recoverable sealing material, the forces on the wall can be easily estimated.

This force must be such that it deforms the interior wall surface enough to seal the components, but does not create a force that would crack the wall or substrate.

For contoured thermally resettable seals, the force on the edge is similar to that of McGraw-Hill.
) published in 1965 by Roar
Book 11 Formula for stress strain (Formu
las for 5tress-8train)”
4th edition, page 303.

By adjusting the height and thickness of the disc, the forces on the walls of the container can be controlled to provide sealed electrical components without any risk of cracking.

The lateral dimension of the deformed disk must be slightly smaller than the lateral dimension of the wall in the litho 1 section.

Thus, for a wall dimension of 0.500 inches, the lateral dimension of the disk is 0.495 inches.

With such dimensions, the disc can be easily placed into the wall cavity in an unstable state, but when warmed it will be deformed by little more than 12,700 millimeters (0,500 inches). Apply pressure to seal the electrical components enclosed within the cavity.

Although using disc-shaped seals is preferred because the disc forces are easily estimated, it should be understood that the specific dimensions and shape of the heat-recoverable seal often depend on the shape of the electronic package. This is something that will be ordered.

Various other shapes of edge forces, including square and rectangular, can be approximated from the stress-strain equation and are within the scope of the present invention.

The shape of the surface of the sealing member is designed and modified to increase the sealing force and to aid the insertion of the member into the wall of the substrate.

Figure 4a is a cross-sectional view of the flat disk before deformation;
The figure shows the same disk after deformation.

When the deformed disk is warmed to its restoring temperature, it will tend to return to its original shape, thus exerting a force on the walls of the container.

Figures 5a and 5b respectively show cross-sections before and after deformation of the disc with large control ridges that help the disc to be inserted into the wall of the container.

Figures 6a and 6b show a flat disc that is deformed into a donut shape.

This shape results in a substantially horizontal force being applied to the walls of the container by this disk when warmed.

FIG. 7 shows the use of a sealing ring so that the sealing member does not directly contact the walls of the container.

Ring 38 is preferably constructed of a rigid material such as Kovar.

Preferably, the ring is shaped with an inwardly bent portion so as to form a ``■'' shape into which the sealing member 14 will fit in a wedge-like manner once it is restored.

The sealing ring 38 has an angled portion 42 and a horizontal portion 40 such that the plane of the horizontal portion 40 and the inner surface of the angled portion 42 form an acute angle.

Unlike a straight sidewall shape, as most clearly shown in FIG. 3, this square shape ensures retention of the disc and a tight seal 1 on the two surfaces of the ring.

Ring 38 is adhered to substrate 20 on metallized pad 22 by known methods such as soldering or brazing.

This ring is placed over the container in the form of a substrate cavity 24 into which electrical components (not shown) are inserted.

The electrical components are connected to input and output image conductors 26.

FIG. 8 shows a method for sealing electrical components by deforming the sealing member in one operation.

An electrical component 6, similar to that shown in FIG.

The top wall of the substrate defines an aperture that is slightly smaller than the undeformed sealing member 30, so that the member 30 is deformed to the lower profile shown in the drawings when inserted.

A portion of the wall 12 can be bent to form a lip 34 on which a concave sealing member 36 rests and is flush with the lip.

This lip also serves as an abutment to prevent damage by preventing the sealing member 30 from coming into contact with the electrical components 6 placed over the mounting pad 8.

In the case of a metal sealing member, the member is inserted and deformed in its unstable martensitic state and allowed to return to its stable austenitic state after insertion.

The element will attempt to return to its flattened original shape, applying pressure to the walls and sealing the container to seal the electrical components.

In the case of plastic sealing members, the thermally recoverable member is deformed during insertion and then heated to apply pressure and seal the electrical components.

Finally, the sealing member employed in the present invention is easily removed to expose electrical components if repair or replacement is required.

Using conventional sealing devices such as sealed glasses or soldered caps, the seal cannot be removed without exposing the package to high temperatures.

To remove the sealing member of the present invention, in the case of a metal member,
The entire package is immersed in liquid nitrogen to cool the thermally recoverable seal below its martensitic transition temperature.

At this temperature the member is deformed and can be removed to expose the electrical components.

In the case of a plastic sealing member, the plastic member is heated to a temperature at which it can be deformed and removed from the package.

The ridge 16, seen most clearly in FIG. 2, allows the sealing member to be grasped for easy removal.

Alternatively, in the case of metal, the sealing member may be in an austenitic state and removed by fracturing.

[Brief explanation of drawings]

FIG. 1 is a top plan view of a container having an electronics package with an electronic component, such as a semiconductor strip, and a thermally recoverable seal placed over it to form a hermetically sealed container in accordance with the present invention; 2 is a sectional view of the container of FIG. 1 with the electrical components and the sealing member inserted; FIG. 3 is an enlarged view of the main part of FIG. 4a=b
Figures 5a"b and 6a"b are sectional views, respectively, of a metal sealing member before and after deformation that can be used to form a sealed container according to the invention, and Figure 7 has a sealing ring. a cross-section of a sealed container suitable for accommodating an electrical component, wherein a sealing member is inserted into the ring and the sealing member is heated and wedged into the sealing ring; 8 and 8 illustrate a method of deforming and inserting a sealing member in one operation to form a sealed container in accordance with the present invention. 2... "Substrate", 4... "Device for electrical connection", 6... "Electrical component"
, 12... "wall", 14... "thermally restorable member" or "thermally restorable sealing member".

Claims (1)

[Scope of Claims] 1' A device 10 comprising a substrate 2 incorporating an electrical component 6 and on which the electrical component 6 is provided, and with which the substrate 2 electrically connects the electrical component 6. and a wall 12 surrounding the electrical component 6, with a thermally recoverable sealing member 14.30 within the area formed by the wall 12 and applying sufficient pressure to seal against the wall 12. A sealed container characterized by: 2. A horizontal portion 4.0 containing the electrical components and having a sealing ring 38, which ring 38 is glued onto the substrate, and an inclined portion 42 surrounding the electrical components.
forming an acute angle with the plane of the sloped portion '42 of said sealing ring 38 and applying sufficient pressure to seal the sloped portion '42 of said sealing ring 38; Sealed container 0 characterized by having a restorable member 14