The present disclosure relates to electronic devices and processes of forming electronic devices, and more particularly to, electronic devices including packaging substrates having electrical conductors within vias and processes of forming the same.
Packaged semiconductor devices can be formed using a packaging process in which a metal-containing leadframe is a starting material from which a plastic substrate if formed. More specifically, the leadframe can include leads that are held in place by other parts the leadframe. Therefore, all of the leads are electrically connected to one another early in the process. The leadframe is attached to a tape, and a molding compound can be formed in voids or other openings between the leads and other areas of the leadframe. The tape can be removed after the molding compound hardens. Portions of the leadframe that connect the leads to one another may be removed after the molding compound has been formed. A die can be attached to a portion of the metal leadframe and its bond pads can be wire bonded to leads of the leadframe. A molding compound can be formed over the leads, die, and wire bonds. A subsequent operation can be used to singulate the semiconductor device so that it can be tested and sold. Typically, a portion of the leadframe will be cut by a saw during the singulation operation.
Embodiments are illustrated by way of example and are not limited in the accompanying figures.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.
The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings.
The terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in textbooks and other sources within the semiconductor and electronic arts.
In a particular embodiment, a combination of the materials can include ABS and polycarbonate (ABS/PC) material, a nylon material, a liquid crystal polymer, or potentially another combination of materials, such as in the form of laminated films or copolymers. In another embodiment, the sheet 200 can include a thermally conductive filler. The thermally conductive filler can include crystal silica (SiO2), aluminum nitride (AlN), silicon nitride (Si3N4), silicon carbide (SiC), alumina (Al2O3), another suitable thermally conductive material, or any combination thereof. In a particular embodiment, a filler or other material is considered thermally conductive when its thermal conductivity is at least 1.3 W/mK.
The dimensions of the sheet 200 can vary depending upon the application. The sheet 200 can be relatively large compared to individual semiconductor devices that will be formed using parts of the sheet 200. In another embodiment, the sheet 200 can correspond to the size of an individual semiconductor device. In other embodiments, other shapes of the sheet 200 may be used while still using the concepts as described herein. Thus, from a top view, the sheet 200 can be a rectangular sheet (for example, a square sheet), a circular sheet, and elliptical-shape the sheet, or another polygon-shaped sheet. After reading this specification, skilled artisans will be able to determine the particular dimensions and shape of the sheet 200 for their particular equipment set and application.
The electrically conductive members can be formed using electroless plating, electrolytic plating, additive plating, conductive ink printing, or any combination thereof. When plating is used, plating can be performed as barrel plating or immersion plating. In an embodiment, an electrically conductive seed layer may be formed before performing a plating process. In a particular embodiment, an electrically conductive ink is printed at locations where the leads 510 are being formed. The holes, where the vias 500 are being formed, may be partially or completely filled with the electrically conductive ink. The printing can be performed such that other areas of the sheet 200 along the major surface as illustrated in
At this point in the process, formation of the packaging substrate is substantially complete. Die attach and other subsequent operations can be performed.
In another embodiment, as illustrated in
In another embodiment,
The concepts as described herein are applicable to many electronic devices and are particularly well suited for semiconductor devices having plastic packaging materials. Costs can be reduced by forming leads by printed, plating, depositing, or otherwise forming conductive members, including vias and leads, at locations where such features are needed or desired. In a particular embodiment, the electrically conductive members, including vias and leads, are formed within and on a plastic or another organic substrate.
Conventional semiconductor devices can have leadframes that extend across many different semiconductor devices, and a molding compound is formed around voids and other open areas of the leadframe. Because the leadframe holds the leads in place during a molding operation to form a substrate, the process of forming conventional semiconductor devices involves significantly more metal-containing material than embodiments as described herein. More particularly, portions of a leadframe that hold adjacent leads in place for a conventional process are not needed for an embodiment as previously described because the packaging substrate is already formed before leads are formed.
Further, within the same conventional semiconductor device, the leads initially are electrically shorted to one another by the leadframe. Thus, the leads need to be electrically separated from one another before completing the formation of the semiconductor device. Separating the leads can be difficult as etching, machining, or both may be used to remove portions of the leadframe necessary to isolate the leads and an electrically conductive paddle from one another. As the pitch of the leads decreases, the lead isolation operation will continue to become more difficult.
Conventional semiconductor devices can be formed using a leadframe that extends across many different semiconductor devices. A singulation operation is used to cut through portions of the leadframe between the different semiconductor devices. An embodiment as described herein does not require a leadframe that extends between semiconductor devices. Because a metal-containing material, such as a metal or a metal alloy, can be disposed completely within individual semiconductor devices and not extend between different semiconductor devices, a singulation operation does not need to cut through such metal-containing material. In a particular embodiment, the singulation operation may cut through only plastic or other organic material(s). A saw blade may be used more times before it wears out. Further, the particular methods used for the singulation operation may be more varied. Still further, because no metal or metal alloy would be exposed at the edge of a semiconductor device, metal corrosion or oxidation may be less likely to occur. Moisture penetration into the semiconductor device may be significantly less than if a metal or metal alloy would be exposed at the edge.
A number of other steps that may need to be performed for conventional semiconductor devices having leadframes. Tape may be applied to the leadframe to hold the leadframe in place and protect external connection surfaces of the leads when a plastic molding compound is used to form the packaging substrate. The tape is subsequently removed after the packaging substrate is formed. Because forming the packaging substrate using the molding compound is a dirty step, cleaning steps are required due to the molding compound and also the use of the tape. By using embodiments described herein, the tape, including its attachment and removal and associated cleaning steps, can be eliminated.
Particular conventional semiconductor devices can include copper leadframes. The copper present at the surfaces of the leads needs to be plated with a solder material to allow proper electrical connections to be made between the leads of the conventional semiconductor devices and wires used in a wire bonding operation. The copper leads may be buffed and plated with lead/tin (Pb/Sn) solder. In particular embodiments, such operations are not required be cause wires or solder can be directly attached to the electrically conductive material.
Leadframes in conventional semiconductor devices have a significant amount of surface area in contact with molding compounds. Many molding compounds do not adhere very well to metals or metal alloys used in leadframe. In embodiments described herein, a leadframe is not used, and therefore, the surface area between metal or metal alloys of the lead and vias is significantly less than if a leadframe were used. Therefore, delamination problems can be significantly reduced when using an embodiment described herein. Also, the coefficient of thermal expansion for metals and metal alloys commonly used for the leadframes in conventional devices is significantly different from the coefficient of thermal expansion for the plastic or other organic material of the package. Embodiments described herein can potentially use an electrically conductive material that has a coefficient of thermal expansion closer to that of the plastic or other organic material within the packaging substrate, the encapsulant, or both.
The concepts described herein can be used with a variety of different packages. An exemplary form of such a package includes a quad flat non-leaded (“QFN”), a ball grid array (“BGA”), a leadless land grid array (“LLGA”), or the like. After reading this specification, skilled artisans will appreciate that other packages can be used with the techniques as previously described.
Many different aspects and embodiments are possible. Some of those aspects and embodiments are described below. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention.
In a first aspect, a process of forming an electronic device can include providing a packaging substrate that includes a first major surface and a second major surface opposite the first major surface, wherein the packaging substrate includes a first unit that corresponds to an area of a packaged semiconductor device, and within the first unit, a first major surface of the packaging substrate is substantially free of an electrical conductor. The process can also include forming a first hole from the first major surface and extending into the packaging substrate, and forming electrically conductive material that includes a first portion and a second portion, wherein the first portion includes a first via that within the first hole, and the second portion includes a first lead that lies along the first major surface of the packaging substrate and overlies and is electrically connected to the first via.
In an embodiment of the first aspect, forming the first hole is performed such that the first hole extends completely to the second major surface, and forming an electrically conductive material is performed such that a third portion of the conductive material includes a second lead that lies along the second major surface of the packaging substrate and underlies and is electrically connected to the first via. In another embodiment, the packaging substrate includes an embedded electrical conductor that is spaced apart from the first major surface and the second major surface, and the first hole extends to the electrical embedded conductor and is spaced apart from the second major surface. The process further includes forming a second hole from the second major surface, wherein the second hole extends to the embedded electrical conductor and is spaced apart from the first major surface. Forming an electrically conductive material further forms a third portion and a fourth portion, wherein the third portion includes a second via that lies within the second hole, and the fourth portion includes a second lead that lies along the second major surface of the packaging substrate and is electrically connected to the first and second vias. In a particular embodiment, the first via extends in a first direction from the first major surface towards the second major surface, the second via extends in a second direction from the second major surface towards the first major surface, and the first direction is laterally offset from the second direction.
In still another embodiment of the first aspect, forming the conductive material includes plating the conductive material. In a particular embodiment, forming the conductive material includes printing a conductive ink before forming the conductive material. In a further embodiment, the packaging substrate includes a plastic material. In a particular embodiment, the plastic material includes a thermally conductive filler.
In yet a further embodiment of the first aspect, the process further includes attaching a die to the packaging substrate with an adhesive compound, wherein the adhesive compound lies between the die and the first via, and encapsulating the die with an encapsulant, wherein substantially no encapsulant is formed between the die and the first via. In another embodiment, the process further includes attaching a die to the packaging substrate, wherein the die includes a bond pad, and wire bonding the bond pad to the electrically conductive material, wherein a bond at the conductive material directly overlies the first via. In still another embodiment,
In still another embodiment of the first aspect, the process further includes attaching a die to packaging substrate, encapsulating the die with an encapsulant, and singulating the packaging substrate into a semiconductor device, wherein during singulating, all electrically conductive components within the first area are spaced apart from the sides of the first unit, wherein the sides are substantially perpendicular to the first and second major surfaces, and wherein singulating is formed such that only an organic material is cut. In a further embodiment, packaging substrate does not include a leadframe. In still a further embodiment, the packing substrate includes acrylonitrile butadiene styrene, polycarbonate, polyamide, polypropylene, polypthalamide, polyester, polyarylamide, polyacetal, polyphenylene oxide, polyetherimide, liquid crystal polymer, fluorine-containing polymer, epoxy molding compound, or any combination thereof. In yet another embodiment, forming the electrically conductive material includes electrolessly plating the electrically conductive material, performing an additive plating process, electroless plating the electrically conductive material, conductive ink printing, or any combination thereof.
In a second aspect, an electronic device can include a packaging substrate that includes a first major surface and a second major surface opposite the first major surface. The packaging substrate can further includes a plastic base material having a first hole therein, wherein the first hole extends from the first major surface into the packaging base material, a first via within the first hole, and a first lead lying along the first major surface of the packaging substrate and electrically connected to the first via. The electronic device can also include a die attached to the packaging substrate, wherein the die includes a bond pad, and an electrical connection between the bond pad and the first lead, wherein the electrical connection is attached to the first lead directly above the first via.
In an embodiment of the second aspect, the electrical connection includes a wire having a first end and a second end opposite the first end, wherein the first end is bonded to the bond pad, and the second end is bonded to the first lead. In another embodiment, the electrical connection includes solder that is extends to the bond pad and the first lead.
In a third aspect, an electronic device can include a packaging substrate. The packaging substrate can include an organic material including a first major surface and a second major surface opposite the first major surface, a first hole from the first major surface and extending into the organic material, and a plated conductor that includes a plated material. The plated conductor can include a first via within the first hole, wherein the plated material substantially fills the hole, and a first lead lying along the first major surface of the packaging substrate and electrically connected to the first via.
In an embodiment of the third aspect, the electronic device further includes a die attached to the packaging substrate, wherein the die includes a bond pad, and an electrical connection between the bond pad and the plated conductor. In a particular embodiment, the electrical connection includes a wire has a first end and a second end opposite the first end, wherein the first end is bonded to the bond pad, and the second end is bonded to the plated conductor
Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.
Certain features are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges includes each and every value within that range.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.
The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Separate embodiments may also be provided in combination in a single embodiment, and conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.
Number | Date | Country | Kind |
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PI 20094817 | Nov 2009 | MY | national |