Package for integrated circuit die

[Cross-reference to related applications] This application claims to benefit from US Provisional Application No. 60 / 443.470 filed on January 29, 2003, and the content of this application is incorporated herein by reference.

[Statement on Federal-Supported Research or Development] None

[Background of invention] The present application relates to a manufacturing body for a circuit package for an integrated circuit, more specifically, a structure containing a liquid crystal polymer material and a manufacturing method thereof.

Semiconductors and other integrated circuit devices (sometimes referred to as "chips" or "dies") are generally built into the circuit package to protect and electrically facilitate the die. The die is mechanically and thermally connected to printed circuit boards, heat sinks, and the like. Typical circuit packages include a substrate (usually referred to as a "slug" or "flange"), a protective insulating housing and leads extending from the housing. Inside the housing, the leads are either directly electrically connected to the contacts of the die, or more commonly are connected by wires.

The protective housing is made of a dielectric material such as plastic or ceramic and is attached to the flange to encapsulate the die and bonding wires and protect them from the ingress of water vapor and other atmospheric gases. It has become. Most protective housings have two members, a pair of side walls (frames) and a lid, but some housings are molded as an integral part. The order in which the frame and the die are attached to the flange depends on the material of the frame, more specifically, the maximum temperature at which the material can withstand without deformation, and the temperature at which it deforms beyond this. Can be changed.

Circuit packages for high power dies generally include a metal flange, which is often attached to the flange by co-fusion gold soldering. Generally speaking, the flange is provided with mounting structures such as screw holes and threads, which allow the circuit package to be mounted on something such as a heat sink. ing. In practical use, the flange transfers heat from the die to the heat sink.

The high temperatures used to attach the die to the flange can damage or deform the plastic, and the ceramic material can withstand such high temperatures. Therefore, a circuit package using a ceramic frame can be assembled prior to mounting the die.

To match the coefficient of thermal expansion of ceramic frames, the flanges for these frames are typically made of copper tag stainless alloy by powder metallurgy infiltration process. This process is extremely expensive and the resulting alloy has limited thermal conductivity. Thermal conductivity can be improved by the use of copper-molybdenum-copper laminated flanges made by the infiltration process and subsequent lamination process, but these processes are extremely expensive.

Alternatively, the die can be attached to the flange prior to attaching the frame and the die. This attempt allows the use of plastic at low temperatures for the frame, but does not give satisfactory results due to the use of adhesives to attach the frame to the flange and the lid. These adhesives often result in incomplete seals or voids that create gaps between the use of circuit packages. Moreover, users of circuit packages do not like to assemble these parts after checking the number of flanges, frames and lids, or attaching the die to the flanges.

[Outline of Invention] The present invention provides a low cost circuit package with a small number of parts that can withstand the high temperatures of die mounting and provide a hermetically sealed space for the die without the use of adhesives. is there. The structure of this circuit package utilizes several mechanical features and configurations to achieve perfect sealing and temperature resistance. This combination also provides a circuit package that exhibits better conductivity, thermal conductivity and mechanical integrity than conventional circuit packages.

The circuit package contains two parts: a flange / frame / lead combination and a lid. The reed runs through the side wall of the open top frame. The flange includes a die mounting area surrounded by the frame. The inside of the frame is sealed along the boundary between the flange and the frame and between the lead and the frame. The frame material (thermoplastic polymer, preferably liquid crystal polymer) and seal (preferably epoxy) are formulated to withstand the die mounting temperature. Once the die is attached to the flange and the die is electrically bonded to the lead, the lid is welded to the frame to seal the spatial cavity surrounding the die.

The flanges, frames and leads of the circuit package contain one or more structural features that maintain the mechanical integrity of the circuit package without the use of adhesives. These features are that the flanges and leads are mechanically locked to the frame at their respective joints.

In one embodiment, the flange constitutes a frame holding feature that surrounds the die mounting area. This holding feature is, for example, a groove or a ridge, which includes a spliced structure or other undercut cross-sectional shape. The thermoplastic frame is molded into the flange by, for example, injection molding means. During the molding process, the frame is also molded around the leads, which reach the spatial cavity region from the outside of the frame via the side walls of the frame.

One lead holding feature constitutes at least one hole, which penetrates the lead. During the molding process, the thermoplastic material of the frame flows into the holes and then cures in the holes to lock the leads into the frame.

Another lead retention feature constitutes a hook-like edge, ridge or other structural part above or near the lead within the spatial cavity region. This structure is not on the same surface as the lead. During the molding process, a portion of the thermoplastic material of the frame hardens against the outer surface portion of the structure, creating a mechanical barrier that prevents the leads from being pulled out of the frame.

The compositions of the flanges, frames and leads have a matching coefficient of thermal expansion (CTE), which reduces stress at the respective joints between these parts. These compositions also have good thermal conductivity due to the flange and good conductivity due to the lead and the flange. In one embodiment, the flange is made with a high copper content and is augmented with a small amount of zircon, silver or other material. In another embodiment, the leads are made with a high copper content and are augmented with a small amount of iron, phosphorus, zinc and / or other materials. In yet another embodiment, the graphite flakes in the frame form a moisture barrier. These graphite flakes and other additives make the CTE of the frame match the CTE of the flange. An optional film can be applied to the outside or inside of the frame and / or lid to further reduce the degree of moisture penetration into the space cavity.

[Simple description of drawings] These and other features, advantages and embodiments of the present invention can be further clarified by those skilled in the art from the following description with reference to the following accompanying drawings: FIG. 1 is a perspective view of a circuit package without a lid according to one aspect of the present invention. FIG. 2 is a perspective view of the circuit package of FIG. 1 having a lid. FIG. 3 is a top view of one lead frame as used in the manufacture of the circuit package of FIG. FIG. 4A is a top view of the lead frame of FIG. 3 after the frame and flange are molded and mounted. FIG. 4B is a top view of one lead frame of the strip shown in FIG. 4A. FIG. 5A is a partial decomposition diagram of the circuit package of FIG. FIG. 5B is a partial decomposition diagram of another aspect of the circuit package of FIG. 6A-C is a cross-sectional view of the flange of the circuit package of FIG. 1 showing one of the three stages of manufacturing, respectively. 7A-D are schematic views of the die mounted on the flange of the circuit package of FIG. FIG. 8A is a detailed perspective view of the leads of the circuit package of FIG. FIG. 8B is a cross-sectional view of some alternative embodiments of the leads of the circuit package of FIG. FIG. 9 is a schematic cross-sectional view of a frame portion of the circuit package of FIG. FIG. 10 is an enlarged view of a portion showing a seal of the circuit package of FIG. 11A and 11B are cross-sectional views of the circuit package of FIG. 1 showing each of the two aspects of the seal of FIG. FIG. 12 is a graph showing the relationship between viscosity and shear rate for one aspect of a material suitable for use as a seal in FIGS. 10, 11A and 11B. FIG. 13A is a perspective view of the lid for the circuit package of FIG. FIG. 13B is a perspective view of a portion of the lid of FIG. 13A that follows one aspect. FIG. 14 is a flowchart of a method of manufacturing the circuit package of FIG.

[Detailed description of the invention] The present invention provides a low cost circuit package with a small number of parts that can withstand the high temperatures of die mounting and provide a hermetically sealed space for the die without the use of adhesives. is there. FIG. 1 shows an exemplary circuit package 100 according to an embodiment of the present invention. For clarity, this circuit package is shown without a lid. The circuit package 100 includes a flange 102, a frame 104, and two leads 106, 108. The frame 104 electrically insulates the two leads 106, 108 from the flange 102 and from each other. The die 110 is attached to the die attachment area 112 by a co-fusion gold soldering portion 114 or the like. For clarity, only one die is shown in FIG. 1, but generally two or more dies are mounted in the die mounting area 112.

The co-fused gold soldering portion 114 electrically connects the die 110 to the flange 102. The co-fused gold soldering section 114 also dissipates heat from the die 110 to the flange 102. In practical use, the flange 102 is generally attached to a heat sink (not shown) by bolts (not shown) passed through the groove holes 116 and 118. The die 110 is electrically connected to the leads 106 and 108 by wires 120 and 122 and the like. These wires 120, 122 are preferably ultrasonically bonded to the leads 106, 108. One die 110 and two leads 106, 108 are shown, but more dies and / or leads can also be used. FIG. 2 shows a circuit package after the lid 200 is closed, which will be described in detail later.

The circuit package 100 uses several features and configurations to hermetically seal the die into the spatial cavity to withstand high temperatures. As described above, this combination also enhances the degree of conductivity, thermal conductivity, and mechanical integrity of the circuit package 100. The following description begins with an overview of the process for manufacturing circuit package 100. Next, a detailed description of the flange 102 and its manufacture will be given. Following this, a detailed description of the composition of the liquid crystal polymers used for the leads 106, 108, the frame 104, the manufacturing process of the lid 200 and the circuit package 100 will be made.

[Overview of manufacturing] The circuit package 100 according to the present invention is preferably manufactured by being wound around a strip or a reel like a conventional circuit package. FIG. 3 shows a strip-shaped body 300 of a lead frame such as the lead frames 302 and 304. Each lead frame contains two leads, indicated by 306, 308. In one embodiment, when the lead frame strip 300 is punched or etched, a plurality of holes are penetrated through the leads 306, 308. An example of these holes is shown at 310. These holes 310 are used to lock the frame to the leads 306, 308, as described in detail below.

After the lead frame strip 300 is made, the frame is preferably molded by injection molding into each lead frame of the lead frame strip. FIG. 4A shows a lead frame strip 300A after a plurality of frames such as the frame 400 are formed into the plurality of lead frames. FIG. 4B shows one completed lead frame 404. The plurality of lead frames are individually supplied individually, in strips, or rolled up and supplied to a series of manufacturing workers, whereby a die is attached to the lead frame.

[Flange] The flange 102 serves as a base, to which other parts of the circuit package are attached. Further, the flange 102 typically transfers heat from the die to the heat sink and electrically connects one terminal of the die to the printed circuit board. The flange 102 is preferably made of an alloy having a high copper content (at least about 50% copper), is highly conductive and thermally conductive, and is adapted to withstand annealing at die mounting temperatures. The alloy preferably contains at least one trace amount of metal. The flange 102 is preferably composed of at least about 98% copper and about 0.05% to about 1.5% zirconium, but may have another high copper content. The flange 102 is more preferably made of about 99.9% copper and about 0.1% zirconium. The flange 102 is electroplated with nickel about 2.54 μm (about 100 microinch) thick to form a diffusion barrier layer, electroplated with about 1.7 μm (about 65 microinch) gold, and die. Facilitates soldering 110 to the flange.

Separately, the flange 102 may be made of at least about 99.5% copper and about 0.085% silver, but may have another high copper content. Zirconium is preferred over silver because zirconium-containing alloys have a higher copper content and are therefore better in thermal conductivity and conductivity than silver-containing alloys. Due to the copper-zirconium alloy, the thermal conductivity of the flange is superior to the prior art copper-tungsten and copper-molybdenum-copper flanges, and circuit packages using such flanges or dies attached to such flanges It will be possible to output larger output than the conventional package. In addition, copper-zirconium alloys have a higher annealing temperature than most alloys with high copper content and are less distorted when heated to the die mounting temperature.

As described above, the frame 104 is preferably molded into the flange 102 by injection molding. As a result of this molding, the frame sticks to the flange 102, but this sticking method is incomplete and is destroyed by the heat of soldering and operation of the die. In order to solve this problem, the flange 102 preferably includes a mechanical feature that mechanically interlocks the frame 104 with the flange.

This feature is illustrated in FIG. 5A, which is a cross-sectional perspective view of a portion of the circuit package 100 described with reference to FIG. The flange 102 is configured with a frame holding structure 500, which is used to mechanically connect the frame 104 to the flange. When the frame 104 is formed into the flange 102, a part of the material of the frame flows into the frame holding structure portion 500 and is cured to form a key 502. The frame holding structure 500 has a cross-sectional profile, to which the key 50 has a complementary profile. The thus cured key 502 interlocks with the frame holding structure 500 so that the frame 104 is not pulled out of the flange 102 without the addition of adhesive between the frame and the flange. Will be.

The frame holding structure portion 500 includes at least one undercut portion. The holding structure portion 500 has a cross section with a groove, and constitutes undercut portions 504 and 506. Other cross-sectional shapes such as T, L or a disc with a rod may be used.

The frame holding structure portion 500 shown in FIG. 5A is pushed into the adjacent surface of the flange 102, but may rise from the adjacent surface as shown in FIG. 5B. Another form of flange 102A constitutes the frame holding structure portion 500A, which rises firmly from the adjacent surface. When the frame 104A is formed into the flange 102A, a part of the material of the frame flows around along the undercut portions 504A and 506A of the frame holding structure portion 500A and is cured. In this case, the key 502A is configured inside the frame 104A.

Returning to FIG. 5A, the frame holding structure portion 500 is formed on the flange 102 by a series of progressive stamping (a series of punching processes). 6A-6C show cross sections of the frame holding structure 500 at various processing stages. FIG. 6A shows the flange blank 102B before the frame holding structure portion 500 is made.

FIG. 6B shows a flange blank 102C in which a first groove 600 having a rectangular cross section is formed in the flange blank. By this processing operation, walls 602 and 604 are formed in the groove 600. The groove 600 preferably has a width dimension (dimension A) of about 0.508 mm (about 0.02 inch), and has a depth dimension (dimension B) of about 0.508 mm (about 0.02 inch). It is preferable that

FIG. 6C shows the flange 102 after the second groove 606 having a rectangular cross section is formed with respect to the first groove 600. By this second processing operation, the walls 602 and 604 (FIG. 6B) are deformed, and the vicinity of the top of the groove is slightly crushed. The deformed walls 602A and 604A form undercut portions 504 and 506 as described above with reference to FIG. 5A. The second groove 606 preferably has a width dimension (dimension D) of about 1.27 mm (about 0.05 inch) and a depth dimension (dimension of about 0.01 inch) of about 0.254 mm (about 0.01 inch). It is preferably C). The grooved shape formed in this way has a narrow dimension (dimension E) of about 0.1778 mm (about 0.007 inch), and the dimension of the overhang portion is about 0.165 mm (about 0.0065 inch). ) (Dimension F). The overhang portion (F) is preferably at least about 0.127 mm (about 0.005 inch) with respect to the liquid crystal polymer (described later) used for the frame 104.

All these dimensions are familiar to those skilled in the art, such as the size of the flange 102, the material and temperature, the size of the frame 104, the material and temperature, the desired strength, cost or other factors at the joint between the flange and the frame. It can be changed according to the thing.

The flange 102 also includes mechanical features that ensure that heat is well and reliably transferred between the flange and the heat sink. Heat sinks are generally flattened by mechanically polishing one surface. In order to increase the heat conduction of the junction between the circuit package and the heat sink, the circuit package must be snugly snuggled against this flat surface without voids.

The punching process (above) performed to form the frame holding structure 500 deforms the bottom of the flange 102, which prevents the circuit package from leaning flat against the heat sink. In order to improve such deformation, it is preferable to polish the bottom surface of the flange 102 with a lapping machine after punching. Further, or separately, the thickness dimension (dimension G of 5A) is preferably increased by about 3.175 mm (about 0.125 inch) to reduce the amount of deformation due to the stamping process, and the bottom surface of the flange 102. You don't have to polish the wrap.

Due to the difference in thermal conductivity CTE between the die 110 and the flange 102, the flange is deformed when the die is soldered to the flange. 7A-7D are schematics of such a situation. FIG. 7A shows a flange 102D with a flat bottom surface 700 and a die 110 not yet soldered to the flange. The solder material 114A has not yet melted. The CTE of the copper / zirconium flange is about 17 ppm / ° C, while the CTE of the silicon die is about 2.8 ppm / ° C. When the die 110 and the flange 102D are heated and the die is soldered to the flange, the die and the flange expand.

Then, as shown in FIG. 7B, when the die 110 and the flange 102D cool, the co-fused gold solder 114B is immediately cured, but the flange and the die shrink while cooling. The co-fused gold solder 114B is very hard and is not stretched much. Therefore, the upper surface 702 of the flange 102D is constrained by the die 110 whose CTE is much lower than that of the flange. As a result, the upper surface 702 of the flange 102D has a smaller degree of shrinkage than the lower surface 700, and the lower surface has a concave shape, and when the flange is attached to the heat sink, a gap remains.

After soldering, the flange is made slightly convex before soldering in order to counteract the tendency of the flange 102 to be concave. FIG. 7C shows the flange 102 before soldering the die 110 to the flange. The bottom surface 704 of the flange 102 has a shape in which the dimension (dimension H) overhanging the concave surface is larger than the degree to which the concave surface is introduced by soldering. In one embodiment, the bottom surface 704 overhangs at least about 0.00254 mm (about 0.0001 inch) over the length of the flange. In another embodiment, the bottom surface 704 is an overhang between about 0.0127 mm (about 0.0005 inches) and about 0.0254 mm (about 0.0010 inches). This degree of dimensionality depends on various factors such as the number, size and placement of dies soldered to the soldering technology flange used, the length, width and thickness of the flange, and even the configuration of the flange. It will change. Conventional flanges are generally about 1.016 mm or about 1.575 mm (about 0.040 or 0.062 inches) thick. A flange thickness of preferably about 3.175 mm (about 0.125 inches) (dimension G in FIG. 5A) can reduce the amount of deformation due to soldering. The overhang of the bottom surface is preferably formed by a molding process, but may be another process such as sandpaper polishing, bending, casting or fabrication.

FIG. 7D shows the flange 102 after the die 110 has been soldered to the flange 102 and both have cooled. The bottom surface 704 is preferably slightly curved. When the flange 102 is attached to the heat sink, the force that attaches the screw to the heat sink (arrows 706, 708) flattens the flange with respect to the heat sink, improving the thermal conductivity of the joint between the flange and the heat sink. ..

As mentioned above, the flange 102 includes a generally flat die mounting area 112, to which the die is soldered, epoxy glued or otherwise mounted. The die mounting area 112 is preferably flat at about 0.0254 mm (about 0.001 inch) or less per 25.4 mm (inch), more preferably about 0.0127 mm (about 0.001 inch) per 25.4 mm (inch). It is flat below (about 0.0005 inches) so that the die 110 and the die mounting area are nicely co-fused gold solder bonded. Further, the roughness of the die mounting region is preferably about 1.6 μm (about 64 microinch) or less, whereby heat is satisfactorily transferred to the heat sink. When the Phi 110 is attached to the die attachment area 112 using an adhesive such as epoxy, the flatness of the die attachment area is within 0.127 mm (about 0.005 inch) per 25.4 mm (inch). The smoothness is within about 1.6 μm (about 64 microinch).

As described above, the flange 102 includes mounting grooves 116 and 118. Separately, the flange 102 includes a plurality of holes that are either threaded or unthreaded. In these cases, the flange 102 is attached to the heat sink or other alternative by bolts or other fasteners in these openings. Alternatively, the flange 102 can be soldered to a heat sink or other alternative to eliminate the mounting groove.

[Lead] As described above for FIG. 1, the frame 104 is preferably molded by injection molding into the flange 102 and leads 1-6.108. During this molding process, the frame 104 is preferably molded around leads 106.108, which are stretched from the outside of the frame into the spatial cavity region via the side walls of the frame. As a result of this molding, the frame sticks to the leads 106, 108, but this sticking is not perfect and is broken by the heat and operation of the soldering of the die. In order to solve this problem, it is preferable that each of the leads 106 and 108 is provided with one or more lead holding mechanisms so that the litho is fixed to the frame 104.

One of the lead holding mechanisms penetrates each lead through at least one hole 310, as shown in FIG. As described above, these holes 310 are formed in the leads 106 and 108 when the lead frame 300 (FIG. 3) is punched or etched. Each lead 106, 108 preferably includes a plurality of preferably rectangular holes 310 arranged along the line in which the frame 104 contacts the leads. During the molding process, the thermoplastic frame material flows into the holes 310 and hardens, mechanically locking the leads 106 or 108 within the frame 104, and the need for an adhesive added between the leads and the frame. Without it, the lead will not be pulled out of the frame. As shown in FIG. 5A, the plurality of holes 310 are preferably completely covered by frames 1-4.

The conductivity of the leads 106, 108 contributes to the overall performance of the circuit package 100. The conductivity of the leads 106, 108 is proportional to the side surface, that is, the cross-sectional region of the lead that is substantially perpendicular to the direction of current flow through the lead. Since the plurality of holes 310 narrow this cross-sectional area (see the BB line portion of FIG. 8), the number, arrangement, size and shape of the holes can be selected to obtain efficient conductivity of the leads 106 and 108. The loss can be minimized. Preferably, the hole 310 can reduce the cross-sectional area of the lead by up to about 25%, but this reduction can be further reduced as long as the conductivity of the configured leads meets structural criteria.

The rectangular holes 310 cure to maximize the amount of thermoplastic frame material that locks the leads 106, 108, while eliminating the loss of conductivity of the leads. The longer direction of the rectangular hole 310 is preferably parallel to the direction of the current flowing through the leads 106 and 108. Depending on the thickness of the side wall of the frame 104, the hole 310 can be made square.

In another lead holding structure shown in FIG. 8, hook-shaped or bent (hereinafter collectively referred to as hook-shaped) edges 800, ridges, recesses or leads 106 having another structure in the spatial cavity region, It is provided at or near the end of 108. This structure is not coplanar with the leads. As can be seen from FIG. 5A, during the molding process, a portion of the thermoplastic material of the frame hardens at or against the outward facing portion of the structure, thereby preventing the leads 106 from coming out of the frame 104. A mechanical barrier is created. Hook-shaped edges 800, ridges or other structures are formed on leads 106,108 when the lead frame 300 (FIG. 3) is punched. The hook-shaped edge 800 is a preferred embodiment for the lead holding structure, but other shapes can also be used. Cross sections of some acceptable shapes are shown in FIG. 8B with reference numerals 800A-800F.

As mentioned above with reference to FIG. 1, leads 106, 108 are used to electrically connect the die 110 to a circuit package or equivalent. The leads 106, 108 are made from an alloy with a high copper content (at least 50% copper), have good conductivity, and are adapted to the CTE of the frame 104. Leads with a high copper content generally have better conductivity than conventional leads (widely known as alloy 42) with 42% nickel and 55% iron. In addition, the leads 106,108 are about 1.625 μm, which facilitates wire bonding and soldering of the lead to the nickel layer of about 2.54 μm (about 100 microinch), which is the diffusion barrier layer. It is preferably electroplated with a layer of gold (about 65 microinch).

Leads 106 and 108 consist of about 2.1% to about 2.6% iron, about 0.015% to about 0.15% phosphorus, about 0.05% to about 0.2% zinc and the balance. Those made of an alloy that is copper are preferred. The ratio of these materials may be other than this. Reeds 106, 108 are more preferably made of those of about 97.5% copper, about 2.35% iron, about 0.3% phosphorus and about 0.12% zinc. Such alloys are available from Olin Corporation with UNS Identification C19400.

Many other compositions can be applied to the leads 106 and 108. One of these alternatives is about 99.9% copper and about 0.1% zirconium. Such alloys are available from Olin Corporation with UNS Identification C15100. Another proportion of these materials is acceptable. For example, alloys with about 0.05% to about 0.15% zirconium and the rest copper are also acceptable.

Other compositions of leads 106,108 include about 1% to about 2% iron, about 0.01% to about 0.035% phosphorus, about 0.3% to about 1.3% cobalt, about. Includes 0.1% to about 1% tin and the balance is copper. The preferred amount of copper in this composition is 97%. Such alloys are available from Olin Corporation with UNS Identification C19500.

Other compositions of leads 106,108 include about 0.3% to about 1.2% iron, about 0.1% to about 0.4% phosphorus, about 0.01% to about 0.2%. Includes magnesium and the rest is copper. Preferred compositions in this alternative composition are about 0.6% iron, about 0.2% phosphorus, about 0.05% magnesium and about 99% copper. Such alloys are available from Olin Corporation with UNS Identification C19700.

Other alternative compositions of leads 106,108 include about 1.7% to about 2.3% tin, about 0.1% to about 0.4% nickel, an upper limit of about 0.15% phosphorus and Includes those with the balance copper. Such an alloy can be obtained from Mitsubishi Electric Corporation with UNS identification C50710.

Yet another alternative composition of leads 106,108 includes those with about 0.05% to about 1.5% iron, about 0.025% to about 0.045% phosphorus and the balance copper. .. Such alloys are available from Kobe Steel with UNS Identification C19210.

Yet another alternative composition of leads 106,108 is about 0.5% to about 0.15% iron, about 0.5% to about 1.5% tin, about 0.01% to about 0. Includes 035% phosphorus and the balance is copper. Such alloys are available from Mitsubishi Shindoh Co., Ltd. with UNS identification C19520.

Other alternative compositions of leads 106,108 include about 0.15% to about 0.4% chromium, about 0.01% to about 0.4% titanium, about 0.02% to about 0.07. Includes% silicon and the balance is copper. Such alloys are available from Weeland Werke with UNS Identification C18070.

Yet another alternative composition of leads 106,108 is about 0.8% nickel, about 0.15% to about 0.35% silicon, about 0.01% to about 0.05% phosphorus and the balance. Includes those in which is copper. Such alloys are available from San Metal Corporation with UNS Identification C19010.

Other alternative compositions of leads 106,108 include about 2.0% to about 4.8% nickel, about 0.2% to about 1.4% silicon, about 0.05% to about 0.45. Includes% magnesium and the balance is copper. Preferred compositions in this alternative composition are about 3.0% nickel, about 0.65% silicon, about 0.15% magnesium, and about 96.2% copper. Such alloys are available from Olin Corporation with UNS Identification C70250.

Yet another alternative composition of leads 106,108 is about 0.3% to about 0.4% chromium, about 0.2% to about 0.3% tin, about 0.15% to about 0. Includes 25% zinc and the balance is copper. Such alloys are available from Furukawa Electric under the UNS Identification EFTEC-64T.

Other alternative compositions of leads 106,108 include about 2.7% to about 3.7% nickel, about 0.2% to about 1.2% silicon, about 0.1% to about 0.5. Includes% zinc and the balance is copper. Such alloys are available from Kobe Steel under UNS Identification KLF-25.

Yet another alternative composition of leads 106,108 is about 1.9% to about 2.9% nickel, about 0.2% to about 0.6% silicon, about 0.1% to about 0. Includes 2% phosphorus and the balance is copper. Such alloys are available from Mitsubishi Electric Corporation under UNS Identification NF224.

[flame] As described above in connection with FIG. 5A, the frame 104 is molded by injection molding of a thermoplastic material and integrally molded with the flange 102 and leads 106, 108. The material of the flange 102 preferably contains a liquid crystal polymer (LCP), which can withstand the die mounting temperature (AuSn soldering temperature 280-330 ° C. or AuSi soldering temperature 390-420 ° C.). it can. Conventional LCPs melt at a temperature in the range of about 300 ° C to about 330 ° C. The frame 104 contains a base resin and compounds that raise its melting temperature, regulate its coefficient of thermal expansion (CTE), and reduce the permeability of moisture. Practically, the material of the frame 104 including the resins and the compounds is referred to herein as a "thermoplastic compound" or a "frame material (material)".

Examples of acceptable resins are those consisting of p-hydroxybenzoic acid, bisphenol and phthalic acid. Other acceptable formulations include a copolymer of p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA). Other acceptable formulations include tera polymers of HBA, 4-4-biphenol (BP) and terephthalic acid (TA).

FIG. 9 is a schematic cross-sectional view of the frame 104, showing some of the compounds in the thermoplastic. Filler particles are preferably added to the LCP, transforming its CTE into closer harmonization with the CTEs of leads 106 and 108 (approximately 17 ppm / ° C.) and anisotropy of the thermoplastic in the frame 102. Sex is inhibited. The CTE of the frame material is preferably adjusted to be within about 60% of the CTE of the leads 106 and 108. Unequipped 900 spheres, such as talc, preferably 2-3 microns in diameter, added to the LCP, the concentration of which ranges from about 30% to about 40%. Such composites have a CTE of about 7 ppm / ° C to 22 ppm / ° C.

Graphite is preferably added to the LCP to reduce the ingress of moisture. This graphite is preferably in the form of flat graphite flakes 904 (shown in FIG. 9 in the sideways direction (edge-on)), but other shapes of graphite, such as spheres and lumps, are also preferred. Permissible. In addition, graphite flakes 904 bend to some extent during injection and the like, but their effectiveness is not significantly reduced. The term "generally planar graphite flakes" also includes deformed flakes.

The graphite flakes 904 preferably have a layered structure, preferably approximately parallel to the outer surface of the frame 104, thus winding through the passage of moisture ingress. Even if the layer structure is not parallel to the outer surface, the presence of graphite suppresses the ingress of moisture. Graphite flakes 904 also adjust the CTE of the LCP to match the copper alloy of leads 106 and 108 closer. The frame material contains between about 10% and about 70% graphite flakes, preferably between about 40% and about 50%.

As an alternative to graphite flakes, glass fiber 1202 can be added to the LCP to increase stiffness and adjust the CTE of the resulting thermoplastic. In this aspect, the frame material preferably comprises between about 30% and about 50% glass fiber.

Other alternative or additional materials for graphite flakes can be added to the LCP, such as iron powder substrate absorbers, molecular sieve filters (zeolites) and calcium oxide (CaO). Is. Suitable zeolites are available from Sad-Chemistry.

The frame agent is preferably pre-dried prior to injection molding to a moisture content of preferably less than about 0.008%. Further, the injection molding time is preferably less than about 0.2 seconds, assuming that the injection molding time is short. The size of the one-shot injection should be small, preferably less than about 2 grams, to minimize the time it stays in the barrel of the thermoplastic injection molding machine. The gate during injection molding preferably limits the flow of the thermoplastic, thereby increasing the shear force in the thermoplastic to orient the polymer chains and graphite flakes 904. The thermoplastic material is preferably injected at the corners of the frame 104 or between the leads 106 and 108. A minimum mold temperature of about 250 ° F. is preferably maintained during the molding operation to reduce the amount of residual stress in the resulting frame.

A moisture-proof film is preferably attached to the outer surface of the frame 104 to further reduce the ingress of moisture. Alternatively, the film may be affixed to the inside of the frame 104. Acceptable materials include amine-based epoxy resins and are polymer / Al films and polymer / ceramic films available from PPG Industry under the trade name Bairocade.

Seal The frame holding structure 500 (FIG. 5A) and the lead holding structure 800 (FIG. 8A) form a good mechanical joint and suppress the ingress of moisture and atmospheric gas. In addition, the frame 104 is preferably affixed with an additive and a film on the inside or outside to reduce this intrusion. To further reduce ingress, seals 1000 and 1002 are applied inside the frame 104, preferably along the edges of the frame 104, where the frame contacts the leads 106, 108 and also. The frame is in contact with the flange 102. As shown in the cross-sectional view of FIG. 11A, the sealing 1002 is effective in preventing intrusion from between the flange 102 and the frame 104 and preventing intrusion between the frame 104 and the lead 108. As an alternative, two seals, 1002A and 1002B, can be used in place of one seal 1002, as shown in FIG. 11B.

To facilitate good adhesion of the encapsulant to the frame material, it is preferably washed prior to application of the encapsulant. Plasma cleaning is well known to those of skill in the art and oxygen is the predominant medium, but with acceptable results. Alternatively, the frame material can be cleaned with a solvent or etching. A needle with an inner diameter of 0.203 mm (0.008 inch) was used to apply the material for sealing 1000, and an ID needle with an inner diameter of 0.254 mm (0.010 inch) applied the material for sealing 1002. Used to give. Other sizes of needles may be used depending on the desired bead size. A positive displacement wood auger pump is used to inject the encapsulant into the needle to minimize air bubbles in the encapsulant.

The encapsulant is preferably about 58 Pa. At a shear rate of about 0.95 / sec. s and about 128 Pa. It has a viscosity between s and is about 12 Pa. At a shear rate of about 9.5 / sec. s and about 30 Pa. It has a viscosity between s. FIG. 12 includes Graph 1200, which shows the relationship between viscosity and shear rate. Low viscosities are preferred at high shear rates so that the material can be applied quickly. However, high viscosities are preferred at low shear rates, which means that once the material is applied, the material will not flow.

The material is preferably about 3 Pa. s and about 7.4 Pa. It has a caisson viscosity between s. The thixotropy index of the material is preferably between about 3.5 and about 4.6.

Suitable materials for encapsulations 1000 and 1002 include epoxy resins, silicone resins and conformal coatings. Suitable encapsulants include solvents between about 40% and about 60% (eg, acetic acid (2-butyl) ester) and epoxy or silicone resins between about 40% and about 60%. The epoxy resin is, for example, a bisphenol-A type or an alicyclic epoxy resin. A suitable curing agent includes an amine-based curing agent. Alternatively, the encapsulant can be Paralyne D or Parlylene HT obtained from Cockson Electric.

Lid The lid 200 is attached to the frame 104 after the die 110 is attached to the flange 102 and electrically connected to the leads 106, 108. Suitable lids 200 are shown in FIGS. 13A and 13B. The lid 200 is preferably ultrasonically welded to the frame 104, which uses a welding signal with a frequency between about 50 kHz and about 60 kHz and an amplitude of less than about 100 microns (more preferably less than 60 microns). Alternatively, the lid 200 is welded to the frame 104 by laser welding or thermal welding.

Normal ultrasonic plastic welding techniques are not used to seal circuit packages with lids because these traditional techniques utilize low frequency welding, which results in high amplitudes mounted on the circuit packages. It may damage the wiring and connections that have been made. The high welding frequency of the present invention has a low amplitude, and as a result, the wiring and connection are not damaged. The lid is usually glued to the circuit package with an epoxy adhesive. Advantageously, the lid is bonded to the circuit package by ultrasonic welding for a time (about 250 ms) shorter than the curing time of the epoxy resin (about 2 hours).

There is preferably a cushioning fit between the lid 200 and the frame 104 so that both parts of the lid and the frame melt and melt together during ultrasonic welding. As shown in the cross-sectional view of FIG. 13B, the lid 200 preferably includes a frame 104 and a lip 1300 that melts and melts. The lid 200 is preferably made of the same material as the frame 104 as described above. Further, as described above with respect to the frame 104, a moisture-proof film is preferably attached to the lid 200.

Manufacturing details Includes materials and methods used in the manufacture of the flange 102, frame 104, leads 106, 108 and lid 200 of the circuit package 100 and their components, the details of which are described above. FIG. 14 illustrates a simplified flowchart illustrating the method by which the circuit package 100 can be manufactured and used.

At 1400, a first high content copper alloy is produced for the leads 106,108. In 1402, the lead frame is made from a first high content copper alloy made in 1400. In 1404, the holes 310 are perforated and etched or otherwise applied to the lead frame to create one of the lead holding structures. At 1406, the ends of the leads 106, 108 are curled, bent, punched, or etched into the lead frame 300 to create another lead holding structure 800.

At 1408, a second high content copper alloy is produced for the flange 102. In 1410, the flange 102 is made of a second high content copper alloy made in 1408. In 1412, the frame holding structure 500 is created on the flange 102 by the continuous stamping method. Optionally, at 1414, the bottom of the flange 102 is folded. In 1416, the bottom of the flange 102 is convex.

At 1418, graphite flakes, talc and / or glass fiber are added to the liquid crystal polymer to produce a frame material. At 1420, the frame material is dried. At 1422, the frame 104 is formed into flanges 102 and leads 1-6, 108.

At 1424, the interior of the frame 104 and flange 102, i.e. the air cavity region, is cleaned. At 1426, a sealant is applied to seal the boundaries between the frame 104 and the flange 102 and between the frame and the leads 106, 108.

At the 1428, the die 110 is attached to the flange 102. At 1430, the die 110 is ultrasonically wired and coupled to the leads 106, 108. At 1432, the lid 200 is ultrasonically welded to the frame 104.

Although the present invention has been described based on preferred embodiments, those skilled in the art can modify it, but it is still within the scope and spirit of the invention as described in the appended claims. To understand the. For example, a low power die can be glued to the flange with epoxy or a non-soldering adhesive rather than being soldered. Moreover, as is well known to those skilled in the art, alloys typically contain small amounts of impurities, so the compositions described herein do not necessarily add up to 100% in total.

Although the frame holding structure 500 and the convex body H at the bottom of the flange are described in relation to the high content copper flange 102, these creations also apply to regular flanges and flanges from other materials. Although the lead retention structures 310, 800 and their respective are mostly described in relation to high content copper leads, these creations also apply to regular leads and leads made of other materials. Although the frame material has been described in relation to the circuit package 100, this material can advantageously be used in relation to other relations, such as those that require a material that can withstand high temperatures. Examples of other applications of frame materials include high temperature lamination in printed circuit boards (PCBs) and sockets for electronic components, cables, PCBs and the like.

<figref num="1">A perspective view of a circuit package without a lid according to one aspect of the present invention.</figref><figref num="2">FIG. 3 is a perspective view of the circuit package of FIG. 1 having a lid.</figref><figref num="3">Top view of one lead frame as used in the manufacture of the circuit package of FIG.</figref><figref num="4A">Top view of the lead frame of FIG. 3 after the frame and flange are molded and mounted.</figref><figref num="4B">Top view of one lead frame of the strip shown in FIG. 4A.</figref><figref num="5A">Partial fraction decomposition of the circuit package of FIG.</figref><figref num="5B">Partial fraction decomposition view of another aspect of the circuit package of FIG.</figref><figref num="6A">FIG. 6 is a cross-sectional view of a flange of the circuit package of FIG. 1 showing one of the three stages of manufacture.</figref><figref num="6B">FIG. 6 is a cross-sectional view of a flange of the circuit package of FIG. 1 showing one of the three stages of manufacture.</figref><figref num="6C">FIG. 6 is a cross-sectional view of a flange of the circuit package of FIG. 1 showing one of the three stages of manufacture.</figref><figref num="7A">FIG. 6 is a schematic view of a die mounted on the flange of the circuit package of FIG.</figref><figref num="7B">FIG. 6 is a schematic view of a die mounted on the flange of the circuit package of FIG.</figref><figref num="7C">FIG. 6 is a schematic view of a die mounted on the flange of the circuit package of FIG.</figref><figref num="7D">FIG. 6 is a schematic view of a die mounted on the flange of the circuit package of FIG.</figref><figref num="8A">A detailed perspective view of the leads of the circuit package of FIG.</figref><figref num="8B">FIG. 6 is a cross-sectional view of some alternative embodiments of the leads of the circuit package of FIG.</figref><figref num="9">FIG. 6 is a schematic cross-sectional view of a frame portion of the circuit package of FIG.</figref><figref num="10">An enlarged view of a portion showing a seal of the circuit package of FIG.</figref><figref num="11A">FIG. 6 is a cross-sectional view of the circuit package of FIG. 1 showing one of two aspects of the seal of FIG.</figref><figref num="11B">FIG. 6 is a cross-sectional view of the circuit package of FIG. 1 showing the other of the two aspects of the seal of FIG.</figref><figref num="12">FIG. 5 is a graph showing the relationship between viscosity and shear rate for one aspect of a material suitable for use as a seal in FIGS. 10, 11A and 11B.</figref><figref num="13A">FIG. 3 is a perspective view of the lid for the circuit package of FIG.</figref><figref num="13B">FIG. 13A is a perspective view of a portion of the lid according to one embodiment.</figref><figref num="14">The flowchart of the method of manufacturing the circuit package of FIG.</figref>

100 circuit package 102 flange 104 frames 106 lead 108 leads 110 die 112 Die mounting area 114 Co-fusion gold solder 116 slots 118 slots 120 wiring 122 wiring