JPS6041780A - Device for mounting chip or chip carrier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to connections and methods for connecting electrical components, and more particularly to methods for attaching electronic components, particularly chips and chip carrier packages, to each other or to a supporting substrate such as a circuit board. , regarding equipment and materials.

Prior Art The trend in the microcollection industry is to use chip carrier packages (CCPs) or larger chips with connections on the side of the device or at the edge of the device. These are dual inline packages (
DIP) is generally used when there are restrictions on its use. The number of connection terminals in the most common packages ranges from 64 to 156. Chip carrier packages are manufactured with or without leads. The leaded chip carrier package may be soldered directly to a printed circuit board (PCB) or printed on a printed wiring board (PWB). Leadless chip carrier packages are soldered onto ceramic substrates or incorporated into connectors.

Leadless chip carrier packages are typically installed on printed circuit boards using glass/epoxy printed circuit boards or printed circuit boards to avoid the effects of differences in the thermal expansion coefficients of the materials when exposed to temperature fluctuations. attached to the connector. These connectors are complex and costly to produce.

As chip carrier packaging technology improves and becomes more reliable, it becomes possible to solder the package directly onto the printed circuit board to make better use of space on the circuit board or to allow replacement of defective chip carrier packages. There is a tendency to omit connectors even in the case of conventional methods.

The cost of conventional connectors is incomparably high compared to the cost of chip carrier packages.

Therefore, it is extremely advantageous to use chip carrier packages without connectors.

However, using a chip carrier package or printed circuit board without a connector causes the following problems. (1) Changes in surface flatness and non-parallel edges between the chip carrier package and the printed circuit board cause solder joint height to vary. (2) Solder tends to flow out of connections into crevasses and crevices within the chip carrier package. Therefore, it weakens the connection. (3) Gold alloys and solder tend to make weakened joints even more brittle. (4) Failure occurs due to internal shear stress at the connection portion due to the difference in thermal expansion coefficient between the chip carrier package and the printed circuit board. (5
) If there is excess solder or the distance between the joints is small, there is a risk of bridging (short circuit) between the joints. (6) As the density of the package increases, for example, in a typical connector pad, the width is 0.012 inch, the center-to-center spacing is 0.022 inch, etc., the available area for soldering tends to become smaller. (7) Solvent removal and inspection problems from the space between the chip carrier package and the printed circuit board. (3) The solder used to attach the chip carrier package can create solder balls that create electrical problems.

Various proposals have been made to solve the above problems. In order to position a predetermined amount of solder at an appropriate position, a carrier or template is used to form the solder into a predetermined shape corresponding to the part to be connected with the solder (hereinafter referred to as a preformed part). ) can be used. An example of this technology is U.S. Pat.
719981, 3744129, 4209893.42
16350 etc. Furthermore, as a preformed part of the solder pack, US Pat.
3750265, 4099615, 4142286.3
No. 981,320 et al. disclose electrically conductive connectors formed from electrically non-conductive and electrically conductive elastomers.

Although the techniques described above are concerned with applying the solder in the correct amount and in the correct location, and with respect to proper positioning of the carrier or template, these proposals can form small amounts of solder between close locations; There is no mention of the problem of high shear stress at the connection part (brazing of solder, etc.).

Among the several elements mentioned above that must be taken into account for configuring the electrical connection between the chip carrier package and the printed circuit board are temperature fluctuations and the circuit board or rib straight onto which the circuit is mounted. The connection must be constructed in such a way that it can resist stresses due to the effects of differences in thermal expansion coefficients between the material of the chip carrier package and the material of the chip carrier package. In this way, the chip carrier package is made of ceramic material and the circuit board is made of epoxy glass material. And when these elements are exposed to high temperatures, they will expand at different rates, including internal stresses in the connections.

Even though the materials used in the chip carrier package and the circuit board have similar coefficients of thermal expansion, the heating and cooling recycle that occurs when power is applied to the chip carrier package is summarized below. As is well known, if the soldered part is configured in the form of a long column and the length of the column is much larger than the diameter, the internal stress of the connection will be lower, the reliability of the connection will be higher, and the service life will be longer. Become.

U.S. Pat. No. 3,921,285 describes a method for connecting microminiature components to a support member, in which during the initial connection of the microcomponent to the support member,
Alternatively, the height of the connection part is adjusted in a two-step solder flow process.

US Pat. No. 4,412,642 converts a leadless chip carrier into a molded leaded chip carrier by molding a high melting point lead into the chip carrier.

A method or apparatus for connecting a chip carrier to a printed circuit board is further described in, for example, US Pat. No. 3,373,481. Other methods for electrical connection are described in, for example, US Pat. No. 3,750,252.

Although the above-mentioned various known documents point out problems in the connection parts to withstand stress due to thermal repetition, none of them disclose sufficient measures to solve the problem, and none of them disclose reliable measures. It is also not suitable for highly sophisticated production methods.

The solder disclosed in the above-mentioned known document is a conventional solder that easily melts and flows.

This solder flow is due to capillary action when the solder is placed on a wettable material, such as a pre-galvanized connection lead. These conventional solders have a high surface tension and the melted solder can be applied to non-humidifying surfaces such as electrical contact pads or areas surrounded by non-humidifying cover surfaces such as epoxy or ceramic substrates. It tends to become spherical in enclosed areas. If the amount of solder is too large relative to the surface area of the humidifying portion, the solder may flow to the non-humidifying portion and connect electrical contacts in its vicinity.

OBJECTS OF THE INVENTION A first object of the invention is to provide an apparatus and method for precisely positioning and placing a quantity of material to form an electrical connection in a form akin to soldering. be.

Another object of the present invention is to provide a material for forming connections that can sufficiently maintain the shape of the connection portion at melting temperatures for forming electrical connection structures between conductive elements. be.

Another object of the present invention is to provide a method and apparatus for arranging a connecting portion having a predetermined shape using the above-mentioned connection forming material.

Another object of the invention is to provide a method and apparatus of the above-mentioned type for placing a connection-forming material in which the width dimension of the connection part is greater than the height.

It is a further object of the invention to provide an apparatus and method of the above-mentioned type for forming a resilient solder-type connection that is well resistant to fatigue and thermal cycling at the connection. It is.

Yet another object of the invention is to provide an apparatus and method of the above-mentioned type for simultaneously constructing resilient solder-type connections between electrical elements arranged in parallel. .

Yet another object of the invention is to provide an apparatus and method for mounting electronic components to a circuit board.

Yet another object of the invention is to accurately align a chip carrier package and a printed circuit board.

A specific object of this invention is to enable electrical components to resist thermal cycling and fatigue well, and to provide high speed and It is an object of the present invention to provide a method, device, and material for mounting electronic components that enable reliable production of microelectric components or circuit devices.

SUMMARY OF THE INVENTION The above objects and other objects of the invention are achieved by one aspect of the invention described below. According to that aspect,
The interconnect forming and attaching apparatus of the present invention includes a retaining member having a predetermined pattern of holes or openings in which connection forming material is disposed. Each preform has a predetermined shape and typically has a height greater than its cross-sectional dimension. The preform is adapted to maintain its shape after interconnection to form a resilient connection that can substantially resist stress, internal stresses, and fatigue.

The method of this invention includes the following steps. initially positioning a conductive element on one side of a retaining member having apertures spaced apart at predetermined intervals to correspond to preselected positions of the conductive element and placing a connection-forming material in said aperture; coupling between one end of the preform and the first electrically conductive element; positioning the second electrically conductive element on an opposite portion of the retaining member; and the other end of the preform. and a predetermined point on the second conductive element.

The connection between both ends of the preform and the electrically conductive element can be made simultaneously. The present invention is accomplished by placing an interconnect placement device, such as a retaining member having a preform, between parallel patterns of conductive elements, such as conductive pads on an electronic component or conductive pads on a printed circuit board. method can be carried out. Both electrically conductive elements are then bonded together with the preform at the same time. The retaining member may remain within the assembled structure or may be designed to be removed after assembly has been completed. The retaining member may also remain within the assembled device to perform structural, thermal, environmental, and/or electrical functions.

The connection forming material may be a solder material such as solder or a supported solder that maintains its shape as the solder melts or reflows. The term filled solder, as used herein, refers to a solder material that includes a filler material to maintain its substantial shape when the temperature of the filled solder material rises above the melting point of the solder material. The filler material is present in an amount sufficient to maintain the preformed shape of the filled solder material at the temperature at which the solder material melts. This filler may be a powder, or it may be like separate long filaments, or it may be a continuous wool or network of intermixed filaments. good. Preferably the filler is electrically conductive, most preferably metal.

The amount of filler is sufficient to retain the preformed shape of the solder, for example in the form of a column, when the solder melts or reflows. This amount is generally 2
0% to approximately 80% by weight based on the weight of the solder filler mixture, preferably 25% to 70%, more preferably 30% to about 60%, and most preferably Approximately 35% to 40
%.

As used herein, the term supported solder refers to a solder preform shape that is supported by support strands or tapes that are disposed in relation to the outer circumferential surface of the support strand or solder preform shape. The support strand or tape must be solid at the temperature at which the solder melts and is placed on the outer circumference of the preformed shape in a pattern so that the solder shape substantially In this case, the shape of the solder is substantially maintained through the surface tension of the solder. The pattern in which the support strands or tapes are arranged, their spacing, angles, etc. will depend on the cross-sectional dimensions of the solder preform shape, the height of the preform shape, and the surface tension of the contours associated with the support strand or tape material. Depends on shape etc. The pattern may be a tape or a wire or wire braid or other spiral wrap, for example, the spacing of the spiral wraps being controlled by the factors discussed above.

Generally, the shape of the supported solder is a column shape suitable for connecting conductive elements.

The term pillar, as used herein, refers to a shape to which electrically conductive elements can be connected. Typically, this shape is cylindrical, with the length of the cylinder being larger than the cross-sectional dimensions, which facilitates manufacturing and provides greater flexibility in interconnection against thermal expansion of the conductive elements. can do. This pillar may be straight or curved, S-shaped, C-shaped, or spiral. The term column is used here to include cases where the cross-sectional dimension is greater than the height;
Any cross-sectional dimension suitable for connecting the conductive elements for distances between the elements greater than those using conventional solder capillary flow brazing may be used. The pillars do not have to have a uniform cross-sectional area, and may vary in shape, for example, an hourglass, for reasons of flexibility or for other reasons.

The term solder is used herein to also include specific or conventional materials for making connections between elements by melting and hardening. 21.342-
kirkothmerencyclopeded on page 355
This is well known as exemplified in ia.

The term aperture here means a hole through or drilled in the retaining member.

Typically, this hole is retained such that a preform of connection-forming material can be placed in the hole and is exposed on both sides at both ends or protrudes from the retaining member at both ends to form a connection with the conductive element. It extends through the member. However, the opening may also be a hole in the side or edge of the retaining member for receiving a portion of the preform and for forming electrical interconnections and for proper positioning. A variety of these shapes are disclosed herein.

The present invention will be explained below according to various embodiments with reference to the drawings.

Embodiment In this embodiment, solder connections will be described with reference to the application of the present invention to a chip carrier package, hereinafter referred to as a chip device or chip carrier. The connections of this invention to electronic components can be used in a variety of ways, and furthermore, this invention can be used anywhere and at any time for solder connections where there is a need to improve reliability or extend life. It is.

Referring to FIG. 1, there is shown a connection made between a chip device 10 and a circuit board 12 in a manner known in the prior art. Chip device 10 has a plurality of electrical contacts located along its edges.

Only a portion is shown for simplicity. Circuit board 12 has a plurality of complementary contacts on its surface. The circuit board 12 is a printed circuit board (PCB) or a printed wiring board (PW).
B), which is simply referred to as a board or circuit board here. In the known method, the chip device is placed on the surface of a circuit board and the connecting parts are vertically aligned and mechanically and electrically connected by solder connections. In FIG. 1, a chip device 10 and a circuit board 12 are shown.
are provided with conductive layers 14, e.g. of copper, on opposite sides thereof, and these layers are interconnected by a suitable solder material 16, e.g. the well-known tin-zinc alloy solder.

As already mentioned, solder connections are stressed by thermal and mechanical forces. These stresses are caused by mechanical deformation or temperature differences between the chip device and the printed circuit board, and/or differences in coefficients of thermal expansion between the chip device and the printed circuit board. For example, thermal stress may occur due to power supplied to the chip device or due to temperature differences between the chip device and the circuit board, etc. even if there is no difference in the coefficient of thermal expansion of the materials between the chip device and the circuit board. There is.

Connections can undergo extreme fatigue due to repeated heating and cooling cycles, and connections will deteriorate quickly if the stress is very high. Therefore, in order to extend the life of the connection part and improve its reliability, it is necessary to reduce the stress applied to the connection part. In order to determine how stress is reduced, it is necessary to consider the factors that control the generation of stress at the connection.

In FIG. 2, a column-shaped connecting portion 18 is shown, and FIGS. 3A and 3B show the height H for an applied force F.
It shows the relationship between F and F of a column with diameter D. As is clear from the illustration, the column-shaped connections have a longer lifespan due to their better resistance to stress. The selection of height and diameter is determined by size and material. A detailed analysis of similar connected structures can be found in E. A.
Wilson.

“I” presented at the 33rd Electronic Components Conference, May 16-18, 1983.
exploration into Geometer
icInfluence on Integrated
320 of “Circules BumpStrain”
From pages 327 to 327, the advantages of columnar shapes are confirmed.

By reducing the peak stress as mentioned above,
It is clear that the number of repetitions required before fatigue occurs increases with respect to cyclic stress.

The life of a solder joint can be substantially improved by only a small increase in the height of the solder joint. Similarly, the life of the solder joint can be increased by reducing the diameter of the solder joint. It has an advantage in that the packing density can be improved by increasing the height of the connecting portion and decreasing the diameter. The above evaluation is effective in describing the effects and characteristics expected by the apparatus and method of the present invention.

However, it is also useful to verify performance by experimentally testing the device of the present invention.

In embodiments of the present invention, an apparatus for precisely placing elongated cylindrical preformed solder sections in place reduces stress, increases longevity, and improves packaging density. This is one advantage of the present invention. In the embodiment shown in FIG. 4, an interconnect preform positioner 20 includes a retaining member 22 made of a conductive material.

Retaining member 22 has substantially the same shape and dimensions as a chip carrier for preform positioning and mounting used for mounting to a chip carrier on a suitable substrate, such as a circuit board. The holding member 22 has a notch 2 in the center.
4, forming a frame or border,
As shown in FIG. 5, holes 26 are formed at predetermined intervals in this frame portion for receiving preformed solder portions 28 in the form of elongated cylinders.

The location of the plurality of holes 26 in the retaining member 22 is determined by the spacing and location of the conductive contacts located at the end of the chip carrier to which it is attached. Generally, the height of each solder preform 28 is configured to be somewhat higher than the thickness of the retaining member 22 such that the upper and lower edges of each solder preform 28 extend beyond the corresponding surface of the retaining member 22. and
In use, these exposed surfaces make physical contact with corresponding conductive pads on the chip carrier and the circuit board.

Although not specifically shown in FIG. 4, the preform positioning system includes means for properly positioning and aligning the retaining member 22 with respect to the chip carrier and the circuit board, and includes means for properly positioning and aligning the retaining member 22 with respect to the chip carrier and the circuit board. the conductive pads on the circuit board and the post-shaped solder preforms are properly aligned. Such positioning means are well known and may include chamfered corners that mate with similarly shaped surfaces formed on the chip carrier. One or more corners form an index notch. Additionally, alignment pins are provided with holes for receiving pins that match locating holes provided on the bottom surface of the retaining member 22 or on the circuit board. A combination of such positioning mechanisms may be employed in the holding member 22.

It is also possible to vary the solder material so that the solder preform compresses under the weight of the chip carrier to be loaded. The compressibility of this solder preform is due to the fact that the chip carrier and circuit board are not actually flat and therefore the length of the solder column must be varied during the soldering process to accommodate these irregularities, as discussed above. The compressibility of is important.

The retaining member 22 may be made of any material, but is preferably a non-conductive material. The material has a desired thickness of 1
It may be a single sheet or a stack of sheets or layers, or it may be a thin sheet or layer of a suitable material.

Furthermore, it may be formed of a plurality of elements exhibiting a sheet-like structure. Such materials include, but are not limited to those mentioned above, glass mats and high temperature polymer materials such as Ultem (
General Electric Company's trademark name) etc. are used. The material of the holding member 22 should have sufficient rigidity and be heat resistant enough to withstand the soldering process at the location where the solder is to be attached.

Preferably there are two types of retaining members. These are 1
One is removable and the other is a permanently attached member to the connecting part.

Removable types include those that can be dissolved, broken, or segmented or deformed without damaging the preform. Segmented retaining members that are permanently attached and can be removed after interconnection are also within the scope of the invention. The holding member 22 in FIG.
A weakened portion as shown by 9 or a line resembling a notch is provided. In this way, the retaining member 22 can be removed on one side or on multiple sides and in various directions. The retaining member 22 may initially be formed from separate elements, as discussed below.

The removable retaining member may be, for example, a conductive material such as aluminum foil to maintain the position of the preform during interconnection. It is important that the retaining member is not connected to the preform during the connection process.

The holding member may be formed of a thin sheet of solder material that melts and flows like solder during the soldering process. The remaining retaining member is preferably a non-conductive and relatively flexible material so as not to interfere with movement of the preform column. In addition, impedance matching connections are formed when made of a combination of conductive and dielectric materials to provide a transmission line or microstrip effect or to form a coaxial type shield around a preform. can do. In other embodiments, the retaining member may be comprised of a material that is normally non-conductive, but becomes conductive when a certain threshold voltage is exceeded. This threshold voltage is set at a voltage just above the normal operating voltage of the device. A retaining member of this configuration can protect the chip device by providing a short circuit against transient overvoltages caused by electrostatic discharge or other electrical faults.

In some applications, it is desirable that the holding member be constructed of a material that exhibits heat recovery properties. This type of retaining member may be reinforced with fiberglass or similar materials that provide controlled thermal expansion.

However, holes are provided locally to hold the solder posts so that their diameter shrinks during the soldering process, causing the solder posts to protrude upwards and align the chip carrier package with the printed circuit board. It's okay.

Although FIGS. 4 and 7-10 show the retaining member being provided for positioning only the interconnect preform, other elements may be positioned by the retaining member and the chip assembly. and may be mounted on a circuit board.

A heat sink device may be provided in the central opening of the holding member shown in FIG. The upcarrier package and printed circuit board may also be joined together during a soldering process. Similarly, vibration dampers, stiffeners, or Veltier-type coolers may be attached to the chip carrier package and printed wire board. An electrical ground plane may also be provided in close proximity to the interconnect preform to advantageously modify electrical impedance characteristics similar to the microstrip board configuration.

FIG. 4 shows a square peripheral array of interconnects. However, arrays of other patterns can also be used in this invention. A matrix of linear interconnections can also be provided.

Partially filled non-linear arrays can also be provided.

Random type interconnect systems can also be created if the interconnects are assembled close enough to each other. In this type of system, the interconnect density is much higher than the density of the pads on the chip carrier package and printed wire board, so that statistically at least one interconnect preform is interconnected. Should be composed between pad sets. In this type of retention system the interconnections are completely random. A retaining member of this type ideally consists of a plurality of interconnected elements, each having at least one opening. In FIG. 4, elements 31 are shown in perspective, the elements being effectively bundled together or permanently or momentarily joined together with a suitable adhesive material or in any suitable manner to form a sheet-like configuration. The cross section may be uniform or random in order to obtain the desired shape.

Such bundled types of retaining members can also be made by continuously extruding the retaining members between preforms, and then cutting the extruded members into discrete pieces that are aligned axially. The resulting materials are bundled and properly joined as a holding member, and the joined material is sliced at right angles to the axial alignment direction to create a positioning device for preforming. Further, in the shape shown in FIG. 4, the holding member 22
ideally may be stamped out of a sheet material by a press, or alternatively may be cut from a sheet material. In the process of forming the holding member, the holder shape and the central notch 24 can be formed by punching at the same time, as well as the appropriately spaced holes 26 and the insertion of the solder preforms into the holes. be able to. The fabrication of the retaining member 22 can be completed in the step in which the cutouts and alignment surfaces are stamped out of sheet material.

Then, a technique is used to create a hole into which a solder preform is inserted. Other manufacturing methods, such as molding or insert molding, can also be used in the present invention.

The retaining member 22 may be made from a single sheet or a stack of sheets of heat-recoverable material such that the retaining member is press stamped from the sheet of material with a hole formed therein and the solder preform inserted into the hole. be done. The retaining member is then heated to a temperature sufficient to reduce the diameter of the holes 26 but not melt the solder preform. By manufacturing the retaining member 22 using a heat-recoverable material, the hole has a predetermined shape, for example an hourglass shape, which varies in diameter such that in the middle part it is smaller than the diameter in the end parts. There is an advantage that it can be done. These holes are enlarged to a diameter that is larger than the diameter of the preform so that the preform can be easily inserted, and then when the retaining member is heated and thermally recovered, each hole will open. The preform is secured within the retaining member by being reduced to be substantially equal to the diameter of the preform. Furthermore, by using a heat-recoverable material, the hourglass-shaped portion of the hole is secured to the solder preform by a retaining member made of heat-recoverable material when heated to make a solder connection by the process of reflowing the solder. It has the advantage of being strongly tightened, improving the flexibility of the column-shaped connection part, reducing stress, and improving the reliability of the connection part.

Furthermore, by using a heat recoverable material for the retaining member 22, the final shape of the solder connection portion can be controlled.

This allows the preform to be tightly clamped against the hole by partially using heat-recoverable material. Thus, during the soldering process, when sufficient heat is applied to the retaining member for further thermal recovery, the diameter of the hole is reduced and provides a clamping force against the molten or softened preform. Due to this effect, the height of the columnar joint portion tends to be larger than the thickness of the holding member 22.

Although the holding member 22 in FIG. 4 is shown as a frame shape, the holding member is made of a sheet-like material with no notches, and the solder preforming portion is shaped according to the number, position, shape, etc. of the conductive pads to be connected. They may be appropriately arranged in the required number, position, and shape over the entire surface of the holding member.

This preform 28 is formed of a suitable connection-forming material, such as a material that is at least partially molten or softened to connect to the conductive element and bond when cooled, such as a filled solder, a supported material, etc. It can be made of solder or conductive elastomer material. The preform can be made by a variety of suitable techniques, such as continuously extruding solder material through a die of predetermined size and cutting the extrusion to the appropriate length. The preformed portion may be formed by molding. Filler solder is used to maintain the columnar shape during the soldering process, and metal or non-metallic powder is embedded in the solder preform. This state is shown in FIG. For example, the small pieces 30 made of a metal material such as a copper piece can be mixed with a predetermined substance and the mixture is extruded to embed the small pieces 30 in the preform. As shown in FIG. 6, the scattered pieces are aligned along the longitudinal axis within the extruded product.

This alignment is accomplished during the extrusion operation by applying magnetic force or simply by force applied by the extruder to the extruded material or by shearing.

The materials mixed into the solder should have a melting point equal to or higher than the melting point of the solder, and should also have good metallurgical and mechanical and electrical properties. For fillers other than copper, nickel, high temperature polymers, glass films with high crisscrossing, etc. are used. These materials may be loose powders or may be one long strand or many strands continuous within each preform. The solder may completely cover the fiber strands, or
Alternatively, the accumulation may occur only at the ends of suitably inherently conductive fibers.

Additionally, interconnect material or solder may be added in a separate operation. In this manner, a continuous conductor or fiber bundle is held by the retaining member and installation is completed by dipping the assembly into molten solder.

The solder flows into or wets or seals the parts to provide electrical and mechanical interconnections.

Additionally, the powder within the filled solder may be aligned in any other desired alignment manner, and the relative content of the powder in the solder preforms and the relative size of the powder relative to the height of each preform may be This can be determined depending on the requirements of the connection to be made. In addition, the surface of the solder preform may be coated with a suitable solvent, or only the end portions of the preform may be coated with a solvent to ensure proper flow of the solder during the soldering process. Each contact surface on the pad may be coated. This solvent may be contained within the preform.

The use of preform locator mount 20 to mount chip carrier 32 onto a suitable substrate, such as circuit board 34, is illustrated in FIGS. 7 and 8. Holding member 2
2 is fixed with the solder preform 28 and grounded between the bottom surface of the chip carrier 32 and the top surface of the circuit board 34. When properly positioned, the end portions of each solder preform 28 contact the conductive contact portions of the chip carrier and the conductive portions of the circuit board 34. A chip carrier alignment hole 36 is then provided which is vertically aligned with a corresponding hole 38 in the circuit board and a hole 39 in the preform positioner, and pins are inserted into the holes 36, 38 and 39. The chip carrier 32 is aligned relative to the circuit board 34 by a method such as. After the soldering process, the ends of the post-shaped solder preforms 28 are firmly bonded to the conductive contact portions of the chip carrier 32 and the conductive portions of the circuit board 34, as shown in FIG.

Although FIG. 4 shows a flat stamped retaining member, this retaining member could be made by stamping or by folding or molding into a cup-shaped structure to which the chip carrier package is secured. A pressure sensitive or heat melt adhesive can be provided as a catch mechanism within the retaining member to allow attachment of the chip carrier to the chip carrier package prior to attachment with the printed wire board. The assembly is attached to the printed wire board using fasteners, pinch mechanisms, alignment devices such as holes and pins, and the like. In order to fix the position during the soldering process or during the reflowing of the solder, an adhesive or a pin can be provided in the center of the surface of the holding element as already described with respect to FIG.

Although FIG. 4 shows a single retaining member, these parts may conveniently be provided in conjunction with a suitable packaging assembly, such as a bandolier, and a mounting assembly.

During the soldering or resolder process, suitable means are utilized to maintain good contact between the chip carrier 32 and the conductive elements of the circuit board 34 until the connection is solidified.

Such maintenance means are already known. A technique for providing such a holding force is shown in FIGS. 9 and 10, and can be applied to components associated with the solder preform.

As shown in FIG. 9, the indicated number of solder preforms 28
are disposed in holes provided in a holding member 40 made of a heat-recoverable material and each having a depression or depression 42 formed on its surface. By forming the recess 42, a protrusion 4 is formed on the opposite surface of the holding member 40 corresponding to the recess.
4 is formed. The raised flat surface of protrusion 44 is coated with a suitable adhesive 46. The recesses 42 and protrusions 44 are formed by pressing the opposing surfaces of the holder 40 using a die of an appropriate shape, as shown in FIG.
2 and the other surface has a protrusion 44 protruding from it, and can be formed by pressing. Chip carrier 32
Once installed between the chip carrier and the circuit board 34, the ends of each solder preform 28 contact the conductive elements 10 and 12 of the chip carrier and the circuit board, and the adhesive on the surface of the protrusion 44 contacts the conductive elements 10 and 12 of the chip carrier and circuit board. Agents 46 contact opposing surfaces of the chip carrier and circuit board, respectively, thus retaining the chip carrier to the circuit board. The holding member 4 is heated during the soldering process.
0 heat-recoverable material is restored in a known manner to restore the chip carrier 32 to the circuit boat shape, the chip carrier 32 is pulled toward the circuit boat 34, and the contact elements of each device are wetted with solder. Make it.

The shapes of the recesses and protrusions shown in FIGS. 9 and 10 may be changed to any other suitable shape desired. The shape of the trapezoidal depressions 42 and projections 44 shown in the figure can form a relatively wide surface on which the adhesive 46 can be applied.
There is an advantage that depressions and protrusions can be easily formed in the 0. The large area adhesive layer provides strong adhesion to the respective surfaces of chip carrier 32 and circuit board 34, and the shrinkage force provided by the heat resilient material of retaining member 40 pulls the chip carrier toward circuit board 34. Apply sufficient force to attract the object. Furthermore, the shape serves to provide air evacuation between the chip carrier and the circuit board. Applying adhesive to the flat holding member for simply fixing the device to the circuit board and the chip carrier with or without heat shrinkage or for vibration damping, as already discussed. I can do it.

The solder preform has so far been considered to have a slender cylindrical shape, but it can take on various shapes as appropriate depending on the mounting needs. Preforms of portal, hexagonal or other cross-sectional shapes can be used. Yet another shape is the first
1A, 11C, 12 and 13. The S-shaped preform shape shown in FIGS. 11A-C allows for relatively large displacements between the chip carrier 32 and the circuit board 34 at the fastening points at the connection without creating unnecessary stresses. Allows for greater flexibility. An inverted S-shaped preform 48 as shown in FIG.
Provide a wide upper part of the preform that contacts 2. The preform 48 has two parallel holder layers 50
and is supported by 52.

The S-shaped preformed part 54 shown in FIG.
It has the same advantages as the preform 48 shown in the figure and also forms two probe areas P and P' which are used to test whether an electrical connection is made. do. These shapes may be used when forming a connection part along the periphery of the chip carrier where the contacts are provided at predetermined intervals along the edge of the chip carrier as long as the probe area is such that the connection part is easily accessible. It is advantageous for

Preform 54, like preform 48, is supported by parallel retaining member layers 50 and 52.

Preforms 48 and 54 are manufactured, and retaining members 50 and 52 are manufactured.
In securing the preform, the initially straight member is inserted into corresponding holes drilled vertically in layers 50 and 52 of the retaining member, and then the end portions of the preform are It is bent as shown in Figures 11A and 11B.

The S-shaped preform 56 shown in Figure 11C is substantially thicker than the thickness of the individual retention member layers 50 and 52 (shown in Figures 11A and 11B). Otherwise, preform 56 has the same advantages as those obtained with preforms 48 and 54.

The preform 60 shown in FIG. 12 has a C-shape, and the retaining member 58 is
It is attached as appropriate along the edge of 8. Due to its unique shape, the C-shaped preform 60 is most advantageous when disposed along the periphery of the retaining member 58. Preform 60 provides an excellent connection surface when used for continuity testing between chip carrier 32 and circuit board 34.

Although the preform section has generally been described with respect to filled solder, it may be preformed with a long continuous conductive material, such as a wire with supported solder, filled solder, or supported solder material. You can also create a division. These solder member portions are provided at the end portions of the preform for connection purposes. In some methods, the preform can be a solder or a conductive elastomer. These materials may be continuous conductive strands, each strand having a filler solder or support at the ends of the strand for interconnection purposes as described with respect to FIGS. 11-13. It may also be made of a conductive material together with the solder pillars. Chip carrier 32
For maximum flexibility and resiliency between the circuit board 34 and the circuit board 34, a coil spring shaped preform 62 is provided.
As shown in the figure. The shape of FIG. 13 is ideal for the above purpose. The preforms 62 can be easily formed by extruding the filled solder material as a continuous extrudate, shaping the extrudate into a coil spring shape to the desired diameter and length, and forming each spring shaped preform. is held in place within the retaining member 58. The resiliency of the preform 62 can be controlled substantially in a manner similar to controlling the parameters that regulate the performance of known springs, i.e., by controlling the diameter dimension of each turn of a coil spring and the length of the spring. This is done by controlling the diameter of the extrudate used to make the spring.

This spring shape can be made with the supported solder disclosed herein.

Since each solder preform is placed in a given position, the shape of the preform is designed to meet the requirements needed for a particular connection. In this way, for example, the diameter and height of a cylindrical preform provided in one location may be different from that of a preform in another location tailored to the specific requirements of the desired connection. are different. Because each connection has a unique shape, a different solder preform is used. A cylindrical preform and a preform shaped as shown in FIGS. 11 to 13 to provide elasticity and to accommodate stress phenomena in one or more special solder connections. It is also possible to use a combination of preformed parts of various different shapes.

FIG. 14 shows an embodiment of the invention of a preform using supported solder. FIG. 14A shows a solder post supported by wire strands in the form of a wire braid 72. FIG. Figure 14B shows
A solder post is shown supported by a wire strand 82 wrapped around the post in a helical configuration.

In the braided or helical wire embodiment, the diameter of the posts and the spacing between the wires are such that the solder posts substantially retain the shape of the solder as it melts for the wire used. Set. 1st
Figure 4B shows a supported solder post 91 using metal tape or ribbon 92. Figure 14C shows the supported solder post after the connection has been made;
In this figure, the shape of the supported solder posts is maintained, while the solder is shown forming strings 94 at interconnecting sections 10 and 12. The solder in the supported solder posts will flow a little to form a string, and this post will act as a reservoir for the solder which is slightly recessed as shown by strings 95 between the tape supports. This supported solder post property improves the post's flexibility and also has advantages in the manufacturing process. A tape that is particularly useful for interconnect pads with a center-to-center spacing of 0.050 inch is, for example, 0.003 inch thick and 0.013 inch wide, and 0.02 to 0.025 inch wide.
The copper tape is wrapped around an inch diameter solder post with a spacing of 0.008 inch to 0.010 inch between wraps of tape. Supported solder posts are obtained by using filled solder instead of conventional solder.

Supported solder is obtained by wrapping supporting strands or tape around the outside of a pillar-shaped solder, such as solder wire. In this method, the support strands can be constructed by a braid or bandage placed around the solder wire and the wrapped solder wire, and then predetermined to form a post with the desired dimensions as is useful in this invention. cut to length. Similarly, a metal tape is wrapped around the solder wire and the wrapped solder wire is cut to the desired length. Supported solder involves dipping a prefabricated support, such as a wire braid or a spirally woven wire or tape, into a suitable molten solder to fill the interior space within the support with solder. It can be made by solidifying the solder. This method is obtained by forming into long sections and cutting to the required length to create the desired columnar object. In this way, the supported solder posts are formed in-situ within the retaining member of the present invention. For example, a spiral metal tape is placed within an opening in a retaining member, filled with molten solder in a flow soldering operation, and then cooled. If desired, the supported solder posts within the supported retaining member serve to form an interconnect from which the retaining member can be removed, if desired. The formation of the supported solder post can be carried out simultaneously with the assembly of the electrically conductive elements, the solder support, such as a spiral metal tape in the holding member, being filled and the joint part being assembled during the soldering operation. formed at the end of a solder column supported by It has been found to be useful to reflow the solder in cases where the solder wire is wrapped by tape and does not have enough solder to cut to the desired length of the post section used in this invention. Cut out parts.

The interconnect preform positioning or mounting apparatus of the present invention provides a unique and convenient to use technique for precisely positioning multiple preforms between a chip carrier and a circuit board to which the chip carrier is attached. be done.

By using a cylindrical column solder preform, a low bending stiffness and therefore a low shear stress in the solder joint can be obtained, and thereby a high fatigue resistance in the connection can be obtained. By using the columnar preform of the present invention, the desired columnar shape can be maintained during the soldering process, and the formed solder connection can have a columnar shape with low shear stress. .

In addition to the embodiments described in FIGS. 9 and 10, the interconnect preform attachment device may be provided with or without a release paper or release cover;
There can be a layer of pressure sensitive adhesive on the surface.

This adhesive layer will maintain the chip package on the device and the device on the circuit board during handling prior to the soldering or resolder process. This adhesive layer is attached in such a way that it does not interfere with the soldering or resolder process.

The retaining member is made of a high temperature resistant material to withstand the heat applied during the soldering or resolder process. The retaining member is then made of an electrically insulating material that remains after the soldering process to act as an electrical insulator and a seal to the surroundings.

Conversely, the retaining member may be made of a material that is thermofusible, chemically fusible, or removable, such that the retaining member is melted or removed from the mounting part after soldering, so that the solvent can be removed. A gap may also be provided for other steps to complete the installation.

Although this invention has been described with reference to an embodiment using an elongated cylindrical column, the apparatus, article, method, and substance of this invention do not require that the material constituting the connecting portion be in the form of an elongated material, and can be used in compact spaces or In cases where current velocity is more important than thermal cycling, shapes that are wider than length or height, or disk or wafer shapes may also work well. do. Further, the present invention provides that the interconnection points of the electrically conductive elements or the end portions of the preforms may be coated with solder cream, such as by a screening process, to improve or strengthen the connection efficiency.

In this invention, the technical idea shown in the embodiments is to attach the chip to a chip carrier, to attach the chip directly to a circuit board, or to attach a chip carrier package with lead wires or a hybrid thick film type chip carrier to a circuit board. It can also be used in cases where it is mounted on a board. A multiple preform attachment system or large scale attachment system allows simultaneous bonding of multiple chip carrier packages. Additionally, the interconnect preform attachment device may be installed between two circuit boards for vertically interconnecting the conductive pads of the printed boards.

Although various embodiments have been described, it is clear that various modifications can be made within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an enlarged perspective view of a prior art solder connection between a chip device and a circuit board; FIG. 2 is a perspective view of a connection forming a post-shaped connection; and FIG. 3B shows the column section of FIG. 2 as a fixed shoulder beam, showing the forces acting for the purpose considering mutual displacements and stresses, FIG. 3B with one end fixed; 4 is a view of the column of FIG. 2 shown as a beam with the other end guided and the other end showing the deformation as a result of relative movement; FIG. 5 is a perspective view of an embodiment showing a plurality of column-shaped preforms bonded to a retaining member in the form of a perimeter type carrier element; FIG. Side view showing one of the columns, No. 6
The figure is a sectional view taken along the line ■-■ in Figure 5 showing a column-shaped preformed part containing a filler to hold the column shape, and Figure 7 is a cross-sectional view of the column-shaped preformed part including a filler to maintain the column shape. 4 is a cross-sectional view of the preform attachment device of FIG. 4 placed between two structures to be attached; FIG. 8 is a view showing the solder connection completed and the retaining member of the preform attachment device removed; , No. 9
10 is a partially sectional side view showing the mounting device of FIG. 9 in a position after a solder connection has been made; FIGS. 11A-11C are related to the present invention; FIG. Figures 12 and 13 are diagrams showing other shapes of the solder preform used as well as other opening shapes in the holding member, and Figures 14A to 14D. Figure 14C is a side view of an embodiment of the supported solder post of the present invention, with Figure 14C showing the post after the solder connections have been made and the retaining member has been removed. 22... Holding member, 24... Notch, 26...
Hole, 28...preformed part.

Claims (18)

[Claims] (1) a retaining member having a plurality of apertures spaced apart to correspond to a plurality of preselected points on a conductive element; and a retaining member comprising a conductive connection forming material positioned or supported within the apertures; The conductive contact forming material at the ends of the posts substantially retains the physical shape of the preform even when the filled solder, supported solder, or solder melts or the elastomer softens. 1. A connecting device for a conductive element, comprising a preformed part containing a solder or a conductive elastomer that maintains the conductive element. (2) While the solder is in a melted state in the preformed part,
2. The apparatus of claim 1, comprising an electrically conductive interconnect material including a filled solder that substantially maintains the physical shape of the preform. 3. The apparatus of claim 1, wherein the preform includes supported solder such that the solder substantially retains its physical shape while in the molten state. (4) The device according to any one of claims 1 to 3, wherein the preformed part made of the conductive connection forming material has a height larger than the widthwise dimension of its cross section. (5) The device according to claim 2, wherein the filled solder includes a solder disposed with powder or filament made of a material that is solid even at a temperature at which the solder melts. (6) The device according to claim 3, wherein the solder support member includes a spiral metal wire or tape. (7) a first line aligned with one end of the holding member having an aperture spaced apart corresponding to a preselected point on the conductive element;
a preform of a conductive connection-forming material in the opening; a preform of conductive connection forming material between one end of the preform and a preselected point on the first conductive element; joining; a second
arranging a conductive element of the first and second conductive elements, the first and second conductive elements comprising: connecting between a preselected point on the second conductive material and a lower end of the preform; A method of making elastic connections between preselected points on elements. (8) According to claim 7, the preform is simultaneously connected to a preselected point of the first conductive element and a preselected point of the second conductive element. the method of. 9. The method of claim 7, further comprising: removing the retaining member after the preform is connected to the first and second conductive elements. (10) A method according to claim 7 or 8, wherein the preform comprises filled solder or supported solder. (11) Contains solder and discrete powder or filaments made of a material that is solid even at the temperature at which the solder is in a molten state, and in sufficient quantity to maintain the columnar shape even when the solder is molten. 1. A solder column for forming an electrical connection, comprising: a solder filler; (12) The solder column according to claim 1, wherein the filler contains metal powder or filament. (13) The solder column according to claim 11, wherein the filling material includes a metal wire. (14) A support strand or tape made of a solder and a material that is solid even at the temperature in which the solder is molten, and which is placed outside the solder and which is a pillar of the solder even when the solder is molten. A solder post for electrical connections characterized in that it has supporting strands or tape arranged on the outside of the solder in a pattern that maintains its shape. (15) The solder column according to claim 14, wherein the supporting portion includes a metal wire or a metal tape. (16) The solder is in a solid form even at the temperature when the solder is in a molten state, and is 20% to 80% by weight based on the total weight of the solder and filler mixture.
loose powder or filaments present in an amount of 1. A solder material comprising: a filler material; (17) The solder material according to claim 16, wherein the filling material is a metal powder or filament. (18) The solder material according to claim 17, wherein the metal includes copper.