US20020046857A1 - Stress relieving tape bonding interconnect - Google Patents
Stress relieving tape bonding interconnect Download PDFInfo
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- US20020046857A1 US20020046857A1 US09/376,699 US37669999A US2002046857A1 US 20020046857 A1 US20020046857 A1 US 20020046857A1 US 37669999 A US37669999 A US 37669999A US 2002046857 A1 US2002046857 A1 US 2002046857A1
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- lead
- tape
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49572—Lead-frames or other flat leads consisting of thin flexible metallic tape with or without a film carrier
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/498—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers
- H01L23/4985—Flexible insulating substrates
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/02—Bonding areas; Manufacturing methods related thereto
- H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
- H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
- H01L2224/05001—Internal layers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/02—Bonding areas; Manufacturing methods related thereto
- H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
- H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
- H01L2224/05001—Internal layers
- H01L2224/0502—Disposition
- H01L2224/05023—Disposition the whole internal layer protruding from the surface
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/02—Bonding areas; Manufacturing methods related thereto
- H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
- H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
- H01L2224/0554—External layer
- H01L2224/05541—Structure
- H01L2224/05548—Bonding area integrally formed with a redistribution layer on the semiconductor or solid-state body
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/10—Bump connectors; Manufacturing methods related thereto
- H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
- H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/01—Chemical elements
- H01L2924/01019—Potassium [K]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/01—Chemical elements
- H01L2924/01078—Platinum [Pt]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/01—Chemical elements
- H01L2924/01079—Gold [Au]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
- H01R13/58—Means for relieving strain on wire connection, e.g. cord grip, for avoiding loosening of connections between wires and terminals within a coupling device terminating a cable
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/02—Soldered or welded connections
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49121—Beam lead frame or beam lead device
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49124—On flat or curved insulated base, e.g., printed circuit, etc.
- Y10T29/4913—Assembling to base an electrical component, e.g., capacitor, etc.
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49204—Contact or terminal manufacturing
Definitions
- This invention relates generally to tape automated bonding techniques for making electrical connections to integrated circuit devices.
- Integrated circuit devices in the form of an unpackaged die or chip are typically packaged to provide electrical connections. These electrical connections allow the die or chip to be connected to other devices. While it is possible to produce very small elements in integrated circuit devices, because of the mechanical nature of the contacts, generally the contacts must be large relative to the size of the die or chip.
- BGA ball grid array
- An array of solder balls may be coupled to another component by simply contacting bonding pads on one device to the solder balls on another device and heat reflowing to activate the solder.
- Techniques for providing very fine pitch ball grid array packages are commonly called fine pitch ball grid array (FBGA) packaging.
- an integrated circuit device having a plurality of solder balls extending outwardly from the package may simply be placed on a printed circuit board.
- the integrated circuit device When subjected to temperature reflow, the integrated circuit device is automatically connected to the printed circuit board in a so-called surface mount technique.
- Tape automated bonding or TAB provides a high speed technique for providing interconnections to chips.
- an interconnection layer provided in the form of a continuous adhesive tape may be secured to the die in an automated fashion.
- Metallic leads inside the tape layer may then be caused to contact bond pads on the die.
- the other side of the tape layer may be adapted to make connections to the outside world.
- tape layers may be coupled to solder balls.
- the tape may make electrical connection to bond pads on the die on one side and may couple to solder balls on the other side for connection to the outside world.
- a layer of traces within the tape layer may be used to connect the solder balls to the bond pads on the die.
- the tape layers may have a different temperature coefficient of expansion (TCE) than the die or chip to which it is connected. This may result in failure of the interconnection and ultimately the loss of the entire packaged integrated circuit device.
- TCE temperature coefficient of expansion
- the tape layer includes a cantilevered metallic beam which is deflected to make contact with bond pads on the die.
- the beam is bent down to make contact with the die in a way which, in effect, provides a bow in the beam. This is done by pushing the beam down and axially towards its support at the same time, creating the bowed shape. In this way, the relative thermal expansion may be accounted for by bending motion within the bowed cantilevered beam.
- the cantilevered beam is attached on two ends like a bow for a bow and arrow as indicated in FIGS. 6A and 6B.
- the beam simply deflects outwardly, as indicated by the arrow K, on the convex side of the beam to accommodate for the relative motion.
- the beam bows in the direction of the arrow N. Displacement of the ends of the beam, in substantially any direction, is transformed into either an increase or decrease in the bowing of the beam around the same central axis, indicated at C, of the beam.
- This bowing has a beneficial effect in one sense because the stress is advantageously relieved, increasing the life of the system.
- the response of the beam is the same. It always deflects around the same axes. This results in an increase in the amount of strain which must be withstood by the beam.
- the bowing tends to concentrate stresses at the points where the ends of the beam are connected to the die or the tape, thereby creating a stress riser at these locations. Unfortunately, these locations are among the most highly stressed in the entire system, increasing the possibility of failure at these locations.
- a tape bonding system includes a tape and a conductive lead.
- the lead is situated in a surface and is secured to the tape.
- the lead is adapted to be bonded to a bond pad at one location and to be supported by the tape at another location.
- a stress relief is formed in the lead between the two locations. The stress relief is adapted to convert stress along the lead into rotation about an axis substantially transverse to the surface in which the lead is situated.
- FIG. 1 is an enlarged cross-sectional view of one embodiment of the present invention
- FIG. 2 is an enlarged view of a portion of the embodiment shown in FIG. 1;
- FIG. 3 is a partial, enlarged inverted view of a portion of the embodiment shown in FIG. 1 before the lead is deflected to contact a die;
- FIG. 4 is a greatly enlarged bottom plan view of the embodiment shown in FIG. 1 with the solder balls removed;
- FIG. 5A is a schematic bottom plan depiction of the embodiment shown in FIG. 4 illustrating the response of the system to differential thermal expansion
- FIG. 5B is a schematic side elevational depiction corresponding to the view shown in FIG. 3 showing the response of the system of differential thermal expansion
- FIG. 6A is a side view corresponding to FIG. 5B in a prior art embodiment, illustrating the response to compressive stress
- FIG. 6B is a side view of a prior art lead illustrating its response to a compressive stress applied transversely to the direction illustrated in FIG. 6A;
- FIG. 7 is an enlarged bottom plan view of still another embodiment of the present invention.
- FIG. 8 is an enlarged bottom plan view of still another embodiment of the present invention.
- FIG. 9 is an enlarged bottom plan view of yet another embodiment of the present invention.
- FIG. 10 is an enlarged bottom plan view of still another embodiment of the present invention.
- a tape bonding system 10 may include a conductive lead 20 sandwiched between a pair of dielectric layers 12 and 14 .
- the layer 14 may be an elastomeric layer which may be formed, for example, of solder mask material.
- the layer 12 may be formed, for example, of a relatively resilient polyimide layer.
- a plurality of openings 16 may be formed in the dielectric layers 12 and 14 , leaving the lead 20 generally unsupported at those locations by the tape bonding system 10 .
- a plurality of openings in the dielectric layer 14 may be filled by solder balls 18 .
- the tape bonding system 10 may be connected to an integrated circuit die or chip 21 by adhesive securement techniques.
- the die 21 may include bond pads 22 which may be arranged adjacent the openings 16 through the dielectric layers 12 and 14 .
- the conductive lead 20 is deflected in a U-shaped configuration to make electrical contact to a bond pad 22 .
- each lead 20 is electrically coupled to a solder ball 18 as well.
- a pair of leads 20 a and 20 b having a gap 15 between them are situated within the same tape system for one die 21 .
- the lead 20 a is connected to a bond pad 22 a and the lead 20 b is connected to a bond pad 22 b.
- only a single lead may be provided across the die.
- a number of leads may be provided in the tape bonding system 10 displaced in and out of the plane shown in FIG. 1.
- an electrical coupling may be achieved between the die 21 and the solder balls 18 by way of the leads 20 .
- the U-shaped portion 24 of the lead 20 a in the opening 16 is deflected towards the die 21 . This deflection is possible because of the support, at either side of the opening 16 , provided the elastomeric dielectric layer 12 .
- connection to a bond pad 22 may be supplied by deflecting the lead 20 in the Z-axis direction, to assume the dashed line position, causing bends to occur at 26 .
- the lead portion 30 contacts the bond pad 22 the lead may be bonded thereto using heat, sonic energy or other conventional bonding techniques.
- expansion and contraction of the die 21 relative to the tape bonding system 10 may result in bending at the bends 26 which amounts to substantially a spring stress relieving system.
- differential thermal expansion may be accommodated in the Z axis direction.
- TCE temperature coefficients of expansion
- the lead 20 includes a pair of U-shaped stress relieving portions 32 and 34 on either side of the portion 30 secured to the bond pad 22 .
- an anchor tab 36 is provided to anchor the lead 20 on one side of the opening 16 and a supported portion 33 may be provided on the other side of the opening 16 .
- the S-shaped lead portion proximate to the portion 30 is useful in providing greater tolerance in aligning the portion 30 to the bond pad 22 . If there is slight misalignment, the adjacent portions of the stress relieving portions 32 or 34 , indicated at 36 and 38 , may still align with the bond pad 22 providing a useful device.
- FIGS. 5A and 5B show the response to differential thermal expansion/contraction in the directions of the arrows E and G.
- the arrows E correspond to displacement of the tape system 10 in response to thermal expansion of the tape system relative to a device to which the tape system is electrically coupled.
- the arrows G indicate the displacement of the die 21 .
- Differential thermal expansion results in the motion H 1 and H 2 in the two sections 32 and 34 .
- relative thermal expansion in the vertical direction in FIG. 5B may be accommodated for by displacements of the lead 20 in the direction of the arrows H 1 and H 2 .
- Such displacements are effectively rotations about the axis substantially within the surface that the lead 20 occupies.
- differential thermal expansion indicated by arrows A and C results in a different stress relief mechanism.
- stress relieving portions 32 and 34 are caused to deflect around the axes B.
- the leads bow as indicated in FIG. 5B.
- the lead portions on either side of the axis B respond around the axis B traverse to the plane of the lead 20 . In this way, there are effectively two different responses to two different stresses. This effectively increases the life of the leads.
- the stresses illustrated in FIG. 5A are believed to be the most important and most likely stresses. It can be seen that the response of the system is to rotate about the axis B. This removes the stresses from the areas 40 and 42 which are believed to be, in most cases, the most sensitive areas of the entire system. Because of the deflections already induced at these areas, these areas may be the most prone to failure. Therefore, by providing the stress relievers 32 and 34 , the maximum stress and strain have been moved from sensitive areas to areas which have been specifically designed to accommodate such stresses and strains.
- the areas proximate to the rotational axes B may be weakened or reduced in thickness. As a result, these weakened or reduced areas preferentially absorb such stresses and strains.
- strains shown in FIG. 5A are likely to be the most common or predominate strains because they correspond to the major surfaces of the components being joined. It is believed that the predominant thermal expansion will be in these directions because of the greater dimensions, in these directions, of the objects being joined.
- FIGS. 6A and 6B show the response of a system which does not include the stress relievers 32 and 34 .
- the lead acts as effectively a bow, bowing outwardly in the direction of the arrow K. This is also an effective rotation in the direction of the arrows about the axis C.
- the system responds the same way to forces in different directions increasing the concentration of strain which a location encounters over its life.
- the system tends to accentuate the strains which must be borne near the points of attachment indicated by Xs in FIGS. 6A and 6B. These areas, which have already been subject to bending to form the lead, tend to be the most sensitive if not the most strain intolerant regions of the lead system.
- the provision of the stress relievers 32 and 34 improves the performance of the system in response to the predominant strain likely to be encountered and provides an alternate strain relief mechanism which may increase the lifetime of the system 10 in some embodiments.
- FIG. 7 another embodiment of the present invention is illustrated.
- a bond pad 22 is coupled by an L-shaped lead 70 to a support structure 72 .
- the bend 74 acts as a stress reliever.
- the bend 74 causes rotation about an axis transverse to the surface containing the leads 70 .
- a differential response to strains in different directions is created and also the response of the system is moved away from the sensitive connections to support regions.
- the system may not be bilaterally symmetrical.
- the bilateral symmetry shown for example in FIG. 4, has a number of advantages which are described hereinafter.
- FIG. 8 a system which is similar to that shown in FIG. 4 but which provides a pair of opposed stress relievers 80 and 82 in a bilaterally symmetrical system is illustrated.
- the bond pad 22 is situated between a first support 83 and a second support 84 .
- the provision of dual stress relievers 80 and 82 further improves the preferential response of the system about the center portion of the lead as opposed to providing bending response adjacent points of support.
- FIG. 9 is a system similar to that shown in FIG. 5A but using a V-shaped stress reliever 90 as opposed to a U-shaped stress reliever 32 or 34 . While FIG. 9 shows a system which is not bilaterally symmetrical, as in the other cases, a bilaterally symmetrical embodiment may be used as well. Thus, as shown in FIG. 10, a non-bilaterally symmetrical embodiment corresponding to FIG. 4.
- a bilaterally symmetrical embodiment may provide a number of important advantages in some embodiments. It may provide greater tolerance in matching the lead to the bond pad 22 during initial positioning. As explained above, the portions proximate to the region 30 may also assist in ensuring that even if the lead is displaced from the position intended, good contact with the bond pad is still obtained.
- Bilateral symmetry may also tend to balance the forces applied to the stress relievers. That is, opposite rotations occur which may tend to balance the effect supplied to the portions of the lead 20 adjacent the bond 22 .
- the leads 20 may be plated in position.
- the anchor 36 may be coupled to a source of potential which may be utilized to plate the leads 20 in place.
- the leads may be made of one material and then plated with gold material.
- the gold material may be desirable in some cases in making better bonds.
- the lead 20 may have a core made of a highly resilient, ductile material since some stressing of the lead may occur during its downward displacement to make contact to the bond pad 22 .
- a lead, made of a core material chosen for ductility such as aluminum may achieve improved contact characteristics by electroplating gold over the lead for improved contactibility. Examples of other materials for forming the lead core include copper, aluminum, platinum, nickel, and alloys and combinations of those materials.
- connection between the tape and the die 21 may be implemented using well known, commercially available tape automated bonding techniques. Automatic positioning equipment may be used to facilitate alignment between the bonding pads 22 and the regions 30 of the leads 20 . Similarly, conventional techniques may be utilized to couple the leads 20 to the outside world, for example through solder balls. While a ball grid array packaging technique is illustrated, other connection techniques may be used in some embodiments.
- Embodiments of the present invention may be installed using tape automated bonding techniques at relatively high speed.
- the tape may be provided in a continuous form having a plurality of portions having sufficient leads to couple to one die. Succeeding sections may be cut off and applied to a series of succeeding dies.
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Abstract
Description
- This invention relates generally to tape automated bonding techniques for making electrical connections to integrated circuit devices.
- Integrated circuit devices in the form of an unpackaged die or chip are typically packaged to provide electrical connections. These electrical connections allow the die or chip to be connected to other devices. While it is possible to produce very small elements in integrated circuit devices, because of the mechanical nature of the contacts, generally the contacts must be large relative to the size of the die or chip.
- Therefore, it is not uncommon that the contacts on an integrated circuit package take as much surface area as the entire integrated circuit die itself. However, there is a continuing effort to reduce the size and spacing between such contacts to allow ever smaller integrated circuit packages. Such interconnection assemblies in relatively small dimensions are commonly called fine pitch assemblies.
- One popular interconnection technique is a so called ball grid array (BGA). An array of solder balls may be coupled to another component by simply contacting bonding pads on one device to the solder balls on another device and heat reflowing to activate the solder. Techniques for providing very fine pitch ball grid array packages are commonly called fine pitch ball grid array (FBGA) packaging.
- Thus, in one example, an integrated circuit device having a plurality of solder balls extending outwardly from the package may simply be placed on a printed circuit board. When subjected to temperature reflow, the integrated circuit device is automatically connected to the printed circuit board in a so-called surface mount technique.
- Tape automated bonding or TAB provides a high speed technique for providing interconnections to chips. In effect, an interconnection layer provided in the form of a continuous adhesive tape may be secured to the die in an automated fashion. Metallic leads inside the tape layer may then be caused to contact bond pads on the die. At the same time, the other side of the tape layer may be adapted to make connections to the outside world. For example, tape layers may be coupled to solder balls. In this case, the tape may make electrical connection to bond pads on the die on one side and may couple to solder balls on the other side for connection to the outside world. A layer of traces within the tape layer may be used to connect the solder balls to the bond pads on the die.
- Because of the different materials involved in making the die and the tape layers, the tape layers may have a different temperature coefficient of expansion (TCE) than the die or chip to which it is connected. This may result in failure of the interconnection and ultimately the loss of the entire packaged integrated circuit device.
- Techniques are known for facilitating the relative expansion between the tape layer and the die. For example, in one known technique, the tape layer includes a cantilevered metallic beam which is deflected to make contact with bond pads on the die. Through an elaborate procedure, the beam is bent down to make contact with the die in a way which, in effect, provides a bow in the beam. This is done by pushing the beam down and axially towards its support at the same time, creating the bowed shape. In this way, the relative thermal expansion may be accounted for by bending motion within the bowed cantilevered beam.
- As an analogy, the cantilevered beam is attached on two ends like a bow for a bow and arrow as indicated in FIGS. 6A and 6B. When the ends move towards each other as indicated by the arrows I and J in FIG. 6A, the beam simply deflects outwardly, as indicated by the arrow K, on the convex side of the beam to accommodate for the relative motion. Similarly, in response to a vertical displacement, indicated by the arrows L and M in FIG. 6B, the beam bows in the direction of the arrow N. Displacement of the ends of the beam, in substantially any direction, is transformed into either an increase or decrease in the bowing of the beam around the same central axis, indicated at C, of the beam.
- This bowing has a beneficial effect in one sense because the stress is advantageously relieved, increasing the life of the system. However, regardless of the direction of the applied force, the response of the beam is the same. It always deflects around the same axes. This results in an increase in the amount of strain which must be withstood by the beam. In addition, the bowing tends to concentrate stresses at the points where the ends of the beam are connected to the die or the tape, thereby creating a stress riser at these locations. Unfortunately, these locations are among the most highly stressed in the entire system, increasing the possibility of failure at these locations.
- Thus, there is a continuing need for better ways to relieve stress in tape bonding systems and especially for better ways to relieve stress in fine pitch assemblies.
- In accordance with one aspect, a tape bonding system includes a tape and a conductive lead. The lead is situated in a surface and is secured to the tape. The lead is adapted to be bonded to a bond pad at one location and to be supported by the tape at another location. A stress relief is formed in the lead between the two locations. The stress relief is adapted to convert stress along the lead into rotation about an axis substantially transverse to the surface in which the lead is situated.
- Other aspects are described in the accompanying detailed description and claims.
- FIG. 1 is an enlarged cross-sectional view of one embodiment of the present invention;
- FIG. 2 is an enlarged view of a portion of the embodiment shown in FIG. 1;
- FIG. 3 is a partial, enlarged inverted view of a portion of the embodiment shown in FIG. 1 before the lead is deflected to contact a die;
- FIG. 4 is a greatly enlarged bottom plan view of the embodiment shown in FIG. 1 with the solder balls removed;
- FIG. 5A is a schematic bottom plan depiction of the embodiment shown in FIG. 4 illustrating the response of the system to differential thermal expansion;
- FIG. 5B is a schematic side elevational depiction corresponding to the view shown in FIG. 3 showing the response of the system of differential thermal expansion;
- FIG. 6A is a side view corresponding to FIG. 5B in a prior art embodiment, illustrating the response to compressive stress;
- FIG. 6B is a side view of a prior art lead illustrating its response to a compressive stress applied transversely to the direction illustrated in FIG. 6A;
- FIG. 7 is an enlarged bottom plan view of still another embodiment of the present invention;
- FIG. 8 is an enlarged bottom plan view of still another embodiment of the present invention;
- FIG. 9 is an enlarged bottom plan view of yet another embodiment of the present invention; and
- FIG. 10 is an enlarged bottom plan view of still another embodiment of the present invention.
- A
tape bonding system 10, shown in FIG. 1, may include aconductive lead 20 sandwiched between a pair ofdielectric layers layer 14 may be an elastomeric layer which may be formed, for example, of solder mask material. Thelayer 12 may be formed, for example, of a relatively resilient polyimide layer. A plurality ofopenings 16 may be formed in thedielectric layers lead 20 generally unsupported at those locations by thetape bonding system 10. In addition, a plurality of openings in thedielectric layer 14 may be filled bysolder balls 18. - The
tape bonding system 10 may be connected to an integrated circuit die orchip 21 by adhesive securement techniques. The die 21 may includebond pads 22 which may be arranged adjacent theopenings 16 through thedielectric layers conductive lead 20 is deflected in a U-shaped configuration to make electrical contact to abond pad 22. Similarly, each lead 20 is electrically coupled to asolder ball 18 as well. - Thus, in the illustrated embodiment, a pair of
leads gap 15 between them are situated within the same tape system for onedie 21. The lead 20 a is connected to abond pad 22 a and thelead 20 b is connected to abond pad 22 b. However, in some embodiments, only a single lead may be provided across the die. Conventionally however, a number of leads may be provided in thetape bonding system 10 displaced in and out of the plane shown in FIG. 1. Thus, an electrical coupling may be achieved between the die 21 and thesolder balls 18 by way of the leads 20. - As shown in FIG. 2, the
U-shaped portion 24 of the lead 20 a in theopening 16 is deflected towards thedie 21. This deflection is possible because of the support, at either side of theopening 16, provided theelastomeric dielectric layer 12. - As shown in FIG. 3, the connection to a
bond pad 22 may be supplied by deflecting thelead 20 in the Z-axis direction, to assume the dashed line position, causing bends to occur at 26. When thelead portion 30 contacts thebond pad 22, the lead may be bonded thereto using heat, sonic energy or other conventional bonding techniques. In this configuration, best shown in FIG. 3, effectively a leaf spring exists between theportion 30 and the supportedportions lead 20. - Thus, expansion and contraction of the die21 relative to the
tape bonding system 10 may result in bending at thebends 26 which amounts to substantially a spring stress relieving system. In such case, differential thermal expansion may be accommodated in the Z axis direction. In other words, if thedie 21 and thetape bonding system 10 expand or contract differentially because of their different temperature coefficients of expansion (TCE), this may be accommodated for through bending at thebends 26. - Referring to FIG. 4, the overall shape of the
lead 20 in anopening 16 is illustrated. Thelead 20 includes a pair of U-shapedstress relieving portions portion 30 secured to thebond pad 22. In addition, ananchor tab 36 is provided to anchor thelead 20 on one side of theopening 16 and a supported portion 33 may be provided on the other side of theopening 16. The S-shaped lead portion proximate to theportion 30 is useful in providing greater tolerance in aligning theportion 30 to thebond pad 22. If there is slight misalignment, the adjacent portions of thestress relieving portions bond pad 22 providing a useful device. - The response of the
system 10 to differential thermal expansion is best shown in FIGS. 5A and 5B. FIG. 5B shows the response to differential thermal expansion/contraction in the directions of the arrows E and G. In FIG. 5B the arrows E correspond to displacement of thetape system 10 in response to thermal expansion of the tape system relative to a device to which the tape system is electrically coupled. The arrows G indicate the displacement of thedie 21. Differential thermal expansion results in the motion H1 and H2 in the twosections lead 20 in the direction of the arrows H1 and H2. Such displacements are effectively rotations about the axis substantially within the surface that thelead 20 occupies. - Conversely, referring to FIG. 5A, differential thermal expansion indicated by arrows A and C results in a different stress relief mechanism. In this case,
stress relieving portions lead 20. In this way, there are effectively two different responses to two different stresses. This effectively increases the life of the leads. - Particularly, the stresses illustrated in FIG. 5A are believed to be the most important and most likely stresses. It can be seen that the response of the system is to rotate about the axis B. This removes the stresses from the
areas 40 and 42 which are believed to be, in most cases, the most sensitive areas of the entire system. Because of the deflections already induced at these areas, these areas may be the most prone to failure. Therefore, by providing thestress relievers - In some embodiments, to further ensure that these stresses are displaced from the sensitive areas, the areas proximate to the rotational axes B may be weakened or reduced in thickness. As a result, these weakened or reduced areas preferentially absorb such stresses and strains.
- It is believed that the strains shown in FIG. 5A are likely to be the most common or predominate strains because they correspond to the major surfaces of the components being joined. It is believed that the predominant thermal expansion will be in these directions because of the greater dimensions, in these directions, of the objects being joined.
- To further illustrate the point, FIGS. 6A and 6B show the response of a system which does not include the
stress relievers - Moreover, the system tends to accentuate the strains which must be borne near the points of attachment indicated by Xs in FIGS. 6A and 6B. These areas, which have already been subject to bending to form the lead, tend to be the most sensitive if not the most strain intolerant regions of the lead system. Thus, the provision of the
stress relievers system 10 in some embodiments. - Referring to FIG. 7, another embodiment of the present invention is illustrated. In this case, a
bond pad 22 is coupled by an L-shapedlead 70 to asupport structure 72. However in response to the predominant forces of the type indicated in FIG. 5A, thebend 74 acts as a stress reliever. Thebend 74 causes rotation about an axis transverse to the surface containing the leads 70. Again a differential response to strains in different directions is created and also the response of the system is moved away from the sensitive connections to support regions. In this case, the system may not be bilaterally symmetrical. The bilateral symmetry, shown for example in FIG. 4, has a number of advantages which are described hereinafter. - Referring next to FIG. 8, a system which is similar to that shown in FIG. 4 but which provides a pair of
opposed stress relievers bond pad 22 is situated between afirst support 83 and asecond support 84. The provision ofdual stress relievers - FIG. 9 is a system similar to that shown in FIG. 5A but using a V-shaped
stress reliever 90 as opposed to aU-shaped stress reliever - A bilaterally symmetrical embodiment may provide a number of important advantages in some embodiments. It may provide greater tolerance in matching the lead to the
bond pad 22 during initial positioning. As explained above, the portions proximate to theregion 30 may also assist in ensuring that even if the lead is displaced from the position intended, good contact with the bond pad is still obtained. - Bilateral symmetry may also tend to balance the forces applied to the stress relievers. That is, opposite rotations occur which may tend to balance the effect supplied to the portions of the
lead 20 adjacent thebond 22. - Through the use of the
anchor 36, shown in FIG. 4, theleads 20 may be plated in position. Theanchor 36 may be coupled to a source of potential which may be utilized to plate theleads 20 in place. For example, it may be desirable to plate the leads with a gold material. In some cases the leads may be made of one material and then plated with gold material. The gold material may be desirable in some cases in making better bonds. Thelead 20 may have a core made of a highly resilient, ductile material since some stressing of the lead may occur during its downward displacement to make contact to thebond pad 22. Thus, a lead, made of a core material chosen for ductility such as aluminum, may achieve improved contact characteristics by electroplating gold over the lead for improved contactibility. Examples of other materials for forming the lead core include copper, aluminum, platinum, nickel, and alloys and combinations of those materials. - The connection between the tape and the die21 may be implemented using well known, commercially available tape automated bonding techniques. Automatic positioning equipment may be used to facilitate alignment between the
bonding pads 22 and theregions 30 of the leads 20. Similarly, conventional techniques may be utilized to couple theleads 20 to the outside world, for example through solder balls. While a ball grid array packaging technique is illustrated, other connection techniques may be used in some embodiments. - Among other advantages of embodiments of the present invention is that it is no longer necessary to provide elaborate techniques for positioning the lead on the bond pad. For example, in one known technique, it is necessary to displace the lead towards the pad while at the same time, axially compressing the lead towards it point of support. This provides the bowing orientation shown in FIG. 6A and 6B. Because a different mechanism is utilized for absorbing stresses in embodiments of the present invention, it is not necessary to provide this pre-set bow. Eliminating the pre-set bow may simplify the installation of the leads, reducing the likelihood of failure and reducing cost.
- Moreover, with embodiments of the present invention, it is not necessary to break the lead in the process of positioning it. The process of breaking the lead may create weakened or strained locations in the lead resulting in subsequent failure. In addition, a process that does not require the lead breaking step may be considerably simpler to implement.
- Embodiments of the present invention may be installed using tape automated bonding techniques at relatively high speed. The tape may be provided in a continuous form having a plurality of portions having sufficient leads to couple to one die. Succeeding sections may be cut off and applied to a series of succeeding dies.
- While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
Claims (40)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/376,699 US6362429B1 (en) | 1999-08-18 | 1999-08-18 | Stress relieving tape bonding interconnect |
US10/005,410 US6637103B2 (en) | 1999-08-18 | 2001-12-03 | Method of tape bonding |
US10/047,797 US6489564B2 (en) | 1999-08-18 | 2002-01-15 | Stress relieving tape bonding interconnect |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/376,699 US6362429B1 (en) | 1999-08-18 | 1999-08-18 | Stress relieving tape bonding interconnect |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US10/005,410 Division US6637103B2 (en) | 1999-08-18 | 2001-12-03 | Method of tape bonding |
US10/047,797 Continuation US6489564B2 (en) | 1999-08-18 | 2002-01-15 | Stress relieving tape bonding interconnect |
Publications (2)
Publication Number | Publication Date |
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US6362429B1 US6362429B1 (en) | 2002-03-26 |
US20020046857A1 true US20020046857A1 (en) | 2002-04-25 |
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Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
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US09/376,699 Expired - Lifetime US6362429B1 (en) | 1999-08-18 | 1999-08-18 | Stress relieving tape bonding interconnect |
US10/005,410 Expired - Lifetime US6637103B2 (en) | 1999-08-18 | 2001-12-03 | Method of tape bonding |
US10/047,797 Expired - Lifetime US6489564B2 (en) | 1999-08-18 | 2002-01-15 | Stress relieving tape bonding interconnect |
Family Applications After (2)
Application Number | Title | Priority Date | Filing Date |
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US10/005,410 Expired - Lifetime US6637103B2 (en) | 1999-08-18 | 2001-12-03 | Method of tape bonding |
US10/047,797 Expired - Lifetime US6489564B2 (en) | 1999-08-18 | 2002-01-15 | Stress relieving tape bonding interconnect |
Country Status (1)
Country | Link |
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US (3) | US6362429B1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2485016A4 (en) * | 2009-10-01 | 2017-06-21 | Panasonic Corporation | Ultrasonic flow rate measuring unit |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6362429B1 (en) * | 1999-08-18 | 2002-03-26 | Micron Technology, Inc. | Stress relieving tape bonding interconnect |
DE10255277A1 (en) * | 2002-11-26 | 2004-06-03 | Hesse & Knipps Gmbh | Arrangement for contacting between two components |
KR100618898B1 (en) * | 2005-05-24 | 2006-09-01 | 삼성전자주식회사 | Tape package preventing a crack defect in lead bonding process |
US7453139B2 (en) * | 2005-12-27 | 2008-11-18 | Tessera, Inc. | Compliant terminal mountings with vented spaces and methods |
SG139594A1 (en) | 2006-08-04 | 2008-02-29 | Micron Technology Inc | Microelectronic devices and methods for manufacturing microelectronic devices |
KR101358751B1 (en) * | 2007-10-16 | 2014-02-07 | 삼성전자주식회사 | Semiconductor pacakges |
TWI406376B (en) * | 2010-06-15 | 2013-08-21 | Powertech Technology Inc | Semiconductor chip package |
GB2500380A (en) | 2012-03-18 | 2013-09-25 | Effect Photonics B V | Arrangement and method of making electrical connections |
DE102014105861B4 (en) * | 2014-04-25 | 2015-11-05 | Infineon Technologies Ag | Sensor device and method for producing a sensor device |
JP6072366B1 (en) * | 2015-03-10 | 2017-02-01 | オリンパス株式会社 | Endoscopic imaging device |
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BE564212A (en) * | 1957-01-25 | |||
US3864728A (en) * | 1970-11-20 | 1975-02-04 | Siemens Ag | Semiconductor components having bimetallic lead connected thereto |
US4355463A (en) * | 1980-03-24 | 1982-10-26 | National Semiconductor Corporation | Process for hermetically encapsulating semiconductor devices |
US4616412A (en) * | 1981-01-13 | 1986-10-14 | Schroeder Jon M | Method for bonding electrical leads to electronic devices |
DE3248385A1 (en) * | 1982-12-28 | 1984-06-28 | GAO Gesellschaft für Automation und Organisation mbH, 8000 München | ID CARD WITH INTEGRATED CIRCUIT |
US4835847A (en) * | 1988-04-20 | 1989-06-06 | International Business Machines Corp. | Method and apparatus for mounting a flexible film electronic device carrier on a substrate |
JP2501473B2 (en) * | 1989-10-05 | 1996-05-29 | シャープ株式会社 | Manufacturing method of wiring board |
JPH0620731A (en) * | 1992-07-01 | 1994-01-28 | Mitsubishi Electric Corp | Lead, ic device assembling method, ic device, conductive path providing lead, and conductive path providing method |
JP3151219B2 (en) * | 1992-07-24 | 2001-04-03 | テツセラ,インコーポレイテッド | Semiconductor connection structure with detachable lead support and method of manufacturing the same |
US5422514A (en) * | 1993-05-11 | 1995-06-06 | Micromodule Systems, Inc. | Packaging and interconnect system for integrated circuits |
US5493069A (en) * | 1994-08-31 | 1996-02-20 | Heraeus Sensor Gmbh | Method of ultrasonically welding together two conductors |
JP2782673B2 (en) * | 1995-06-23 | 1998-08-06 | 関西日本電気株式会社 | Electroluminescent lamp |
US6271582B1 (en) * | 1997-04-07 | 2001-08-07 | Micron Technology, Inc. | Interdigitated leads-over-chip lead frame, device, and method for supporting an integrated circuit die |
US6093894A (en) * | 1997-05-06 | 2000-07-25 | International Business Machines Corporation | Multiconductor bonded connection assembly with direct thermal compression bonding through a base layer |
KR100282003B1 (en) * | 1997-10-15 | 2001-02-15 | 윤종용 | Chip scale package |
US5895974A (en) | 1998-04-06 | 1999-04-20 | Delco Electronics Corp. | Durable substrate subassembly for transistor switch module |
US6217348B1 (en) * | 1999-08-09 | 2001-04-17 | Hon Hai Precision Ind. Co., Ltd. | Electrical connector |
US6362429B1 (en) * | 1999-08-18 | 2002-03-26 | Micron Technology, Inc. | Stress relieving tape bonding interconnect |
-
1999
- 1999-08-18 US US09/376,699 patent/US6362429B1/en not_active Expired - Lifetime
-
2001
- 2001-12-03 US US10/005,410 patent/US6637103B2/en not_active Expired - Lifetime
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2002
- 2002-01-15 US US10/047,797 patent/US6489564B2/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2485016A4 (en) * | 2009-10-01 | 2017-06-21 | Panasonic Corporation | Ultrasonic flow rate measuring unit |
Also Published As
Publication number | Publication date |
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US20020079124A1 (en) | 2002-06-27 |
US20020084097A1 (en) | 2002-07-04 |
US6489564B2 (en) | 2002-12-03 |
US6637103B2 (en) | 2003-10-28 |
US6362429B1 (en) | 2002-03-26 |
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