This application claims the benefit of priority to Taiwan Patent Application Nos. I06I44I25 and I06I44I26, filed Dec. I5, 20I7. The disclosure of the prior applications is hereby incorporated in its entirety by reference.
The present invention relates to a process for the fabrication of circuit components and in particular to a process for such fabrication in matrix batches for efficiency and cost. More particularly, the present invention relates to a process for the fabrication of circuit components optimized for power rating due to much improved current capacity and heat dissipation.
High-power circuit components like power diode, power transistor and thyristor are indispensable discrete circuit components in power electronics applications. Their performance, reliability and durability characteristics, among others, are critical to important applications such as in the renewable energy and electric vehicles industries. But besides technical characteristics, production costs of these power components is equally important a factor for their widespread commercial use.
Various surface mount packages of existing discrete circuit components such as diodes, light-emitting diodes, transistors and thyristors are commonly available in forms including cylindrical glass/plastic, lead-frame leaded, quad flat-pack leadless and flip-chip packages, among others. Of them, flip-chip package, although featuring the advantage of being small, light and slim, is rarely used in durable large-power applications due to issues of their costly fabrication, application inconvenience and premature aging. Packaging other than flip-chip, by contrast, are considered mainstream in the market. However, as demands for ever more improvements in ever more technology applications grow, existing packaging technology for circuit components, in particular, surface mount power devices has been falling short of many aspects of technical requirements. For example, larger-power components needs good thermal management design to deliver their high-rating performance, yet existing technology has bottlenecks.
Various solutions can be found to provide packaging for circuit components with good heat dissipation and high power. For example, techniques proposed in Taiwan Patent No. I583282 and Taiwan Patent Application No. I05II0I37 are based on the use of two large conductive copper plates. They describe methods for the simultaneously packaging of multiple circuit component dice in a matrix-based fabrication procedure aiming for efficient mass production batches to reduce unit cost.
However, for such techniques based on the use of two large copper plates, tolerances in the dimensioning of their matrix-bearing copper plate substrates, circuit component die bodies, parallelism between their plates, alignment among all parts in the matrix, and thickness of soldering material deployed, all need to be controlled within certain precision ranges. Margin of error for their controlled fabrication parameters is small. Though not impossible, but their precision management and control means elevated cost levels. Poor control easily leads to quality problems to substantially elevate overall costs, obviously due to poor production yield rate.
It is therefore an object of the present invention to provide a process for fabricating circuit components in matrix batches with high efficiency and at low cost.
It is also an object of the present invention to provide a process for fabricating circuit components in matrix batches that provide high power rating due to high current capacity and high heat dissipation.
In order to achieve the above and other objects the present invention provides a process for batch fabrication of circuit components that simultaneously packages multiple circuit component dice in a matrix. Each die having at least two electrodes with one on a top surface and the others on a bottom surface, and each die electrode is electrically connected to a corresponding electrical terminal of the circuit component it is packaged in. The process includes the following steps for each circuit component in the matrix. First, a preparative electrical terminal is formed on a copper substrate for each of the corresponding electrodes of its die. Then, a circuit component die is pick-and-placed onto the copper substrate so that each electrode on the die bottom surface lands on its corresponding preparative electrical terminal. Then, a horizontal conductor plate is pick-and-placed horizontally on top of the circuit component die so that a bottom surface of one end of the horizontal conductor plate lands on the top electrode of the die, The horizontal conductor plate has an opening at the end opposite where it lands on the die, and the opening has at least one vertical conductive surface. Next, a vertical conductor block is pick-and-placed into the opening of the horizontal conductor plate so that a bottom surface of the vertical conductor block lands on the preparative electrical terminal for the top electrode of the die, with the at least one vertical conductive surface of the opening faces the top end side surface of the vertical conductor block. Finally, for all circuit components in the matrix, a thermal reflow is performed to simultaneously melts a soldering material pre-applied to the surface of each preparative electrical terminal of the copper substrate, the surface of the top electrode of the die, and the vertical conductive surface of the opening in the horizontal conductor plate. This is so that the circuit component die and the vertical conductor block are soldered to the copper substrate below and the horizontal conductor plate above.
The present invention also provides the above process wherein the opening in the horizontal conductor plate has a full circumference.
The present invention may also provides the process wherein the opening in the horizontal conductor plate has incomplete circumference.
The present invention also provides a process for batch fabrication of circuit components that simultaneously packages multiple circuit component dice in a matrix. Each die having at least two electrodes with one on a top surface and the others on a bottom surface, and each die electrode is electrically connected to a corresponding electrical terminal of the circuit component it is packaged in. The process includes the following steps for each circuit component in the matrix. First, a preparative electrical terminal is formed on a copper substrate for each of the corresponding electrodes of its die. Then, a circuit component die is pick-and-placed onto the copper substrate so that each electrode on the die bottom surface lands on its corresponding preparative electrical terminal. Then, a vertical conductor block is pick-and-placed so that a bottom surface of the vertical conductor block lands on the preparative electrical terminal for the top electrode of the die. Next, a horizontal conductor plate is pick-and-placed horizontally on top of the circuit component die and the vertical conductor block so that a bottom surface of one end of the horizontal conductor plate lands on the top electrode of the die, and a bottom surface of the other end of the horizontal conductor plates lands on a top surface of the vertical conductor block. Finally, for all circuit components in the matrix, a thermal reflow is performed to simultaneously melts a soldering material pre-applied to the surface of each preparative electrical terminal of the copper substrate, the surface of the top electrode of the die, and the top surface of the vertical conductor block, so that the circuit component die and the vertical conductor block are soldered to the copper substrate below and the horizontal conductor plate above.
The present invention also provides the above process that further performs a nickel-gold or nickel-tin plating to the surface of each and every electrical terminal after the subtractive processing.
The present invention may also provides the process wherein the circuit component is a discrete circuit component having two, three or more electrical terminals.
The present invention may also provides the process wherein the circuit component is a diode.
The present invention may also provides the process wherein the circuit component is a transistor.
The present invention may also provides the process wherein the circuit component is an optical coupler switch.
The present invention may also provides the process wherein the circuit component is an integrated circuit component having at least four electrical terminals.
FIG. I schematically shows a partial region of a copper substrate for the matrix-based fabrication of a circuit component having three electrical terminals according to an embodiment of the present invention;
FIG. I schematically shows a partial region of a copper substrate for the matrix-based fabrication of a circuit component having three electrical terminals according to an embodiment of the present invention. A typical batch fabrication according to the present invention uses a matrix of circuit components numbered in quantities of a few tens by a few tens units, although FIG. I only shows four. Each of the circuit component units is identified by dotted-line frames denoted by reference numeral I020. In this depicted embodiment, preparative electrical terminals I0II and I0I2 for the bottom and top electrodes respectively of the circuit component die (not shown in FIG. I) are formed over the surface of the copper substrate I000.
In the embodiment in FIG. I, these preparative terminals protruding above the upper surface of the copper substrate I000 may be formed by, for example, an etching-based subtractive procedure, an electroplating/chemical reaction-based additive procedure, or a common mechanical procedure such as lathing, milling, drilling, grinding, sawing and stamping etc. on the top surface of the basic copper substrate I000. These preparative terminals I0II and I0I2 for multiple circuit component units I020 can be prepared in batch. In an alternative, any of the preparative terminals may not protrude above the upper surface of the substrate I000.
Then, a horizontal conductor plate 300I is pick-and-placed subsequently, such that the bottom surface at one end (to the left in
Next, a vertical conductor block 3005 is pick-and-placed into the opening 3003 of the horizontal conductor plate 300I. Bottom surface of the vertical conductor block 3005 lands on the preparative electrical terminal I0I2 for the top electrode 2I0 of the die 200. The vertical conductive surfaces 3002 of the opening 3003 facing the top end side surface of the vertical conductor block 3005.
It should be noted that the opening 3003 for the vertical conductor block 3005 may be a hole opened up at the right end of the horizontal conductor plate 300I with a complete circumference. This means the opening 3003 is formed within the edge of the plate 300I. Or, the opening 3003 may be one with an incomplete circumference, meaning that the it is opened on the edge of the plate 300I, as is the case shown in the drawing.
Next, for all circuit components 200 in the matrix already positioned on the copper substrate I000, a thermal reflow can then be performed. This melts soldering material, typically in the form of solder paste pre-applied to the surface of each preparative electrical terminal I0II and I0I2 in the entire matrix on the copper substrate I000, the surface of the top electrode 2I0 of the die 200, and the vertical conductive surfaces 3002 of the opening 3003 in the horizontal conductor plate 300I. When the soldering material solidifies out of the reflow, the circuit component die 200 and the vertical conductor block 3005 are soldered firmly to the copper substrate I000 below and the horizontal conductor plate 300I above.
The soldering material can be typical solder paste containing tin particles, or soldering bars/plates containing tin. The soldering material can be appropriately dispensed in between the pick-and-place operational steps of the component die 200, the horizontal conductor plate 300I, and the vertical conductor block 3005. If, for example, solder paste is used, automatic solder paste dispensing equipment can be used. If, alternatively, solder plates are used, pick-and-place equipment can be used.
As is shown in
According to another embodiment of the present invention, the sequences of the pick-and-placing steps performed for the horizontal conductor plate and the vertical conductor block can be swapped. In this case as is described in
First, a circuit component die 200 is pick-and-placed onto its proper position on the copper substrate (not shown in
Then, a vertical conductor block 3005A is pick-and-placed. Bottom surface of the block 3005A lands on its corresponding preparative electrical terminal I0I2 that forms on the surface of the copper substrate (I000, not shown).
Next, a horizontal conductor plate 300IA is pick-and-placed subsequently. Bottom surface to one end of the horizontal conductor plate 300IA contacts and is in alignment with the top electrode 2I0 of the component die 200, and bottom surface to the other end of the plate 300IA contacts and is in alignment with the top surface of the vertical conductor block 3005A.
After the pick-and-place operation performed for the component die 200, the vertical conductor block 3005A and the horizontal conductor plate 300IA is complete, a thermal reflow procedure can be performed. The reflow procedure can simultaneously melt the soldering material pre-applied to the surface of each preparative electrical terminal, I0II and I0I2, on the copper substrate, the surface of the top electrode of the die 200, and the top surface of the vertical conductor block 3005A, so that the circuit component die 200 and the vertical conductor block 3005A are soldered to the copper substrate I000 below and the horizontal conductor plate 300IA above.
As shown in
Fabrication process technology for circuit components implementing matrix-based batch production in accordance with the example of the component structural unit construction 3I00 of
Comparing the two, although both the horizontal conductor plates and the vertical conductor blocks have slightly different structural constructions, which calls for a swapped pair of sequence steps for the pick-and-place operation, both structural units feature essentially the same optimized construction that supports high power rating. Both feature a large-current circuit within their respective constructions that is supported by a large circuit conductor cross-sectional surface area. The reason for such low electrical resistivity is obvious: The use of a bulky block of vertical conductor (3005, 3005A) that is connected to the component die via a flat and wide horizontal conductor plate (300I, 300IA). Such constructions ensures both large current and large heat dissipation capacities simultaneously that are key to high power rating.
Further, the four soldering surfaces of the unit structural construction of the circuit components depicted in
According to the present invention, after the robust, high-performance unit structures in
A subtractive process can then be performed on the bottom surface of the copper substrate I000 to separate all electrical terminals of all individual circuit components in the entire matrix. A typical subtractive procedure is, for example, a chemical etching process.
Next, the entire matrix shown in
As is generally known to a person skilled in the art, all electrical terminals of every individual circuit component shown in
Again as is generally known to a person skilled in the art, the circuit component fabricated by the process of the present invention can be a discrete circuit component having two, three or more electrical terminals. The circuit component can be a diode, a transistor, or an optical coupling switch. Alternatively, the circuit component can also be an integrated circuit component having at least four electrical terminals.
While the invention has been described by way of example and in terms of the embodiments, it is to be understood that the invention is not limited thereto. Modifications and similar arrangements and procedures can be made by a person skilled in the art without departing from the spirit and scope of the present invention. Therefore, the scope of the appended claims should be accorded with the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Number | Date | Country | Kind |
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106144125 | Dec 2017 | TW | national |
106144126 | Dec 2017 | TW | national |