Component with bonding adhesive

A device comprising a component and an adhesive attached to at least one exterior portion of the component. When the component is on a printed circuit and passed through a reflow operation, the adhesive melts forming a physical bond between the component and the printed circuit. The printed circuit may be a flexible printed circuit or a printed circuit board. The adhesive may melt under and to at least one edge of the component. The adhesive may also melt under and to at least one edge of the component and under and to at least one edge of at least one second component adjacent to the component.

BACKGROUND OF THE INVENTION

The present invention is related to components, and more specifically to a component with bonding adhesive.

As mobile phones and other portable electronic devices continue to get smaller and more complex, more and more traditional circuit boards are being replaced by flexible circuits. These flex circuits, even if held static or stable within the device, are more susceptible to damage to solder joints of mounted components breaking since the base material mounting the components is not rigid. While the use of stiffeners can provide some additional robustness, these are not always ideal due to cost or thickness concerns or the need for bending or movement from the flex itself. Underfill is another solution. The underfill helps facilitate bonding strength of the component to the board by adding more strength than electrical solder joints alone. As noted, for flex circuits, the need for strong bonds is even more important since there is no inherent stiffness in the circuit board itself to contribute to the strength of the component bonding. However, current underfill operations are very messy and require expensive specialized equipment in manufacturing, plus considerations in component layout to allow clearance for glue nozzles that must fit between components to discharge the underfill.

FIG. 1shows a diagram of a typical component. This component represents a resistor where the component100includes an exterior surface101with multiple sides and contact portions102for connecting to a printed circuit via a solder joint. Therefore, the resistor component100would be mounted to a printed circuit via the contact portions102.

FIG. 2shows a diagram of a portion of a printed circuit board or flex tape circuit with mounted components. In the circuit board or flex tape circuit200portion, one or more components201,202,203may be mounted and electrically attached via solder joints (or any other electrical contact mechanisms) to the circuit board or flex tape circuit200portion. For example, component201represents a resistor and may include portions204at either end of the component201for making electrical connection with pads205on the printed circuit via a solder joint. The solder joints between the contact204and pad205bond the component201to the printed circuit200.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, a device includes a component, and an adhesive attached to at least one exterior portion of the component, wherein when the component is on a printed circuit and passed through a heating operation, the adhesive melts forming a physical bond between the component and the printed circuit.

According to another aspect of the present invention, a method for forming a physical bond between a component and a printed circuit includes attaching an adhesive to at least one exterior portion of a component, placing the component on a printed circuit, and passing the printed circuit through a heating operation, wherein the adhesive melts responsive to the heating operation forming a physical bond between the component and the printed circuit.

DETAILED DESCRIPTION OF THE INVENTION

According to embodiments of the present invention, a component to be mounted on a circuit board or flex circuit may come pre-packaged with an amount of releasable adhesive attached to an exterior of the component. The amount of adhesive may be small or large depending on the application or use of the component. The term “component” will be used to help illustrate embodiments of the present invention and may represent any type of component placed on or attached to a printed circuit such as, for example, an electrical component, an electromechanical component, an optical component, an audio component, a mechanical component, etc. Further the term “printed circuit” will be used to help illustrate embodiments of the present invention and may represent any type of printed circuit such as, for example, a printed circuit board or a flexible circuit (e.g., flexible tape circuit). Moreover, the term “heating operation” may represent any type of heating operation that may cause an adhesive and/or solder to melt (e.g., a reflow operation, a rework operation, a solder operation, an oven, etc.).

The adhesive may consist of an adhesive portion or dot on one or more sides of the component. The adhesive may be attached to the component at a manufacturer or distributor of the component. This may streamline the assembly process as the components with adhesive already attached may simply be supplied in the tubes from the manufacturer containing the components directly to the assembly machine or process. In addition, the adhesive may be attached to the component after receipt of the component from a manufacturer or distributor of the component and before a heating operation such as a reflow operation.

Standard equipment may be used to pick-and-place mount the component onto a printed circuit (e.g., flexible circuit or traditional circuit board) in a standard way where when the printed circuit passes through a heating operation (e.g., reflow operation) to melt and cure solder joints, at the same time, this adhesive melts causing the adhesive to form a bond with the component and the printed circuit. The adhesive may flow under and to the edges of the component by force of gravity and surface tension. The bond may be formed once the melted adhesive has hardened. For example, after coming out of the heating process (e.g., a reflow oven) the adhesive then re-hardens, creating a physical bond between the component and the printed circuit in addition to the bond formed with the component and the printed circuit from hardening of the solder joints. Embodiments according to the present invention allow targeted underfill operations without a separate underfill process, without any specialized equipment, and without risk of inadvertently underfilling components where underfill is not desired. Further, no special placement considerations are required to make clearance for underfill equipment nozzles, therefore providing maximum design flexibility to a circuit designer.

According to embodiments of the present invention, the adhesive may be composed of a material having properties such that a normal surface tension in combination with gravity effects and surface energy effects (of the component, board, etc.) cause the adhesive to flow in one or more desired directions. Surface tension relates to a property of the adhesive material related to attraction or repulsion based on surface energy and surface geometry (e.g., of a component). Surface energy relates to the property of the component or circuit board material that makes it more receptive or less receptive to an adhesive bonding to the material. Further, according to embodiments of the present invention, an adhesive that is applied to an exterior surface of a component may have thermal properties that further support holding in or dissipating of heat. In addition, according to embodiments of the present invention, an adhesive attached to an exterior of a component may have insulating properties that further enhance insulating the component that the adhesive is applied to from electromagnetic fields, external temperatures, etc.

Moreover, components pre-packaged with adhesive attached in embodiments according to the present invention are advantageous in that “underfill” may occur on parts that are mounted inside a shield can. These parts may have no physical access at all for traditional underfill nozzles. This provides a solution where no options for underfill exist except to mount the component, underfill, them separately as an additional operation, and then mount the shield can. According to embodiments of the present invention, all steps may happen with just one pick-and-place operation and one heating operation.

FIG. 3shows a diagram of a component with attached adhesive according to an example embodiment of the present invention. The diagram shows a component300that has an exterior surface301composed of multiple sides, and contacts302for electrical connection to a printed circuit. The component300further includes an adhesive303attached to one side of the exterior surface301of the component300. The adhesive303, when the component300is placed in a heating operation, melts and flows under and to the edges of the component300by force of gravity and surface tension. Upon coming out of the heating process (e.g., reflow process), the adhesive303re-hardens creating a physical bond between the component300and the printed circuit (e.g., printed circuit board or flex circuit). Although in this example embodiment, only one adhesive portion is shown on one side of the component300, according to embodiments of the present invention, an adhesive portion may be attached to more than one side of the exterior301of the component300. Further, multiple portions of adhesive303may be attached to one or more sides of an exterior301of a component300.

FIG. 4shows a diagram of a printed circuit with a component with attached adhesive according to an example embodiment of the present invention. As noted previously, to help illustrate embodiments of the present invention, the term “printed circuit” will be used to represent a printed circuit on a printed circuit board as well as a printed circuit on a flexible tape. Therefore, the printed circuit400represents a portion of a printed circuit on a printed circuit board or on a flexible tape, and may include a component401that has an exterior402composed of one or more sides. The printed circuit400has been through a heating operation such as a reflow operation to melt and to cure solder joints between contacts405on the component401and pads404on the printed circuit400. In this example embodiment, an adhesive portion403attached to a side of component401has melted during the heating operation and has flowed and hardened under component401and to the edges of the component401and onto the printed circuit400thereby creating a physical bond between the component401and the printed circuit400. In this figure and other figures, although the adhesive is shown melted with straight-line edges, this is for illustrative purposes only and a melted adhesive may result in any typical shape or form normally occurring with a melted substance that flows under and to the sides of a component and hardens upon cooling, in view of gravity, surface tension and surface energy effects.

The adhesive403provides additional bonding of the component401to the printed circuit400in addition to solder joint connections that attach and provide electrical connection between the component401and circuits on the printed circuit400. This additional bonding is advantageous for printed circuits on flexible tape where the flexible tape may move putting additional stresses upon the solder joints and bonding of the component401to the printed circuit400.

FIG. 5shows a diagram of a portion of a printed circuit with multiple components according to an example embodiment of the present invention. The printed circuit500may be a printed circuit board or flexible circuit and may include one or more components501,503,504,505attached to the printed circuit500. The printed circuit500in this example embodiment has been through a heating operation (e.g., a reflow operation) to melt and cure the solder joints (not shown) attaching the components501,503,504and505to the printed circuit500. Components501,503are shown where an adhesive506,507on a side of each component501,503, respectively, has melted during the heating operation and has flowed and hardened under each component501,503and to the sides of each component501,503forming a bond of the components501,503with the printed circuit500.

FIG. 6shows a diagram of component with an adhesive portion on a top of a component according to an example embodiment of the present invention. The component600may include an exterior portion composed of one or more sides601where an adhesive portion603may be attached to a top side of the component600. The top being a side on the component601located opposite a side of the component closest to a printed circuit. The component600may also include one ore more contacts602for electrically connecting to a pad on a printed circuit. When the component600is passed through a heating operation, the adhesive portion603melts to the sides and underneath of the component600and onto the printed circuit forming a bond between the component600and the printed circuit.

FIG. 7shows a diagram of a component with adhesive on top after a heating operation according to an example embodiment of the present invention. The component700may include an exterior portion701and one or more contacts702. An adhesive portion703was originally on a top of the component700before a heating operation (e.g., a reflow operation). The top being a side on the component700located opposite a side of the component closest to a printed circuit portion704. As a result of the heating operation, the adhesive portion703has melted and hardened around the sides and underneath of the component700, and onto a surface of the printed circuit portion704. In this example embodiment, the adhesive703has flowed down two opposite sides of the component700.

FIG. 8shows a diagram of adhesive attached to a component flowing to an adjacent component according to an example embodiment of the present invention. In this figure, multiple components801,802,803are shown where each component has an associated exterior portion804,806,808, respectively. The three components801,802,803have been through a heating operation (e.g., a reflow operation). Before the heating operation, a first component801and a second component802may have had an adhesive attached to an exterior side of each component801,802. The first component801, the second component802, and a third component803may reside on a printed circuit809adjacent to each other. The first component801and the second component802may each have had a quantity of adhesive805,807attached to the component such that, as shown in the figure, after the heating operation, the adhesive portion805on the first component801has melted and flowed along the side and under the first component801as well as along the side and under the second component802. Further, the adhesive portion807attached to the second component802has melted and flowed along and underneath the side of the second component802as well as to the side and underneath the third component803. Thus, according to embodiments of the present invention, a component may have enough adhesive attached to an exterior of the component such that after passing through a heating operation, the adhesive melts and not only forms a bond for the component with the adhesive attached but also forms a bond for an adjacent component attached to a printed circuit.

FIG. 9shows diagram of a component with a quantity of adhesive for bonding to adjacent components according to an example embodiment of the present invention. Printed circuit900may include one or more components901-906that are attached to the printed circuit900. One or more of the components901-906may include an adhesive portion. In this example embodiment, only one component901includes an adhesive portion907attached to the component901. The adhesive portion907attached to the component901is such that after the printed circuit has passed through a heating operation (e.g., a reflow operation), the adhesive portion907melts and flows around the component901that it is attached to as well as one or more adjacent components902-905. The adhesive907may flow over the top and sides of the one component901and underneath and to the sides of the adjacent components902-905.

FIG. 10shows a diagram of a printed circuit after a heating operation with an adhesive around adjacent components according to an example embodiment of the present invention. A printed circuit1000may include one or more components,1001-1006mounted and attached to the printed circuit1000. In this example embodiment, the printed circuit1000has been through a heating operation (e.g., reflow operation). A first component1001prior to passing through the reflow operation had an adhesive portion1007on a top of the first component1001. The top being a side on the component1001located opposite a side of the component closest to the printed circuit1000. As shown in the figure, due to the heating operation, the adhesive portion1007has melted from a top of the first component1001and has flowed around the component1001as well as around adjacent components1002-1005. The adjacent components1002-1005may all be within a radius of the location of the first component1001. The adhesive1007has flown around the adjacent components and hardened forming a bond with the first component1001and the printed circuit, as well as a bond with the adjacent components1002-1005and the printed circuit1000. The adhesive1007may flow over the top and sides of the first component1001and underneath and to the sides of the adjacent components1002-1005. Moreover, in embodiments according to the present invention, the adhesive1007may not be attached on a top of the first component1001, but may be attached on one or more other exterior portions of the first component1001and flow around the first component1001as well as around adjacent components1002-1005.