Obviousness

Obviousness Analysis under 35 U.S.C. § 103

To establish obviousness under 35 U.S.C. § 103, it must be shown that the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art. This requires identifying: 1) the scope and content of the prior art; 2) the differences between the prior art and the claims at issue; 3) the level of ordinary skill in the pertinent art; and 4) secondary considerations of non-obviousness. A motivation to combine prior art references must also be present.

The patent US9823272B2 generally describes a wafer testing probe card with a flexible circuit board, an elastic piece, and replaceable probes that move up and down. The elastic piece absorbs forces without directly contacting the probes, thereby enabling signals to be transmitted from a device under test (DUT) to a printed circuit board (PCB) via the flexible circuit board and the probes (Claim 1).

Prior Art References:

The following prior art documents were cited during the prosecution of US9823272B2 and are considered for this obviousness analysis:

• US2005/0035775A1 (Zhou): Discloses a probe contact system using a flexible printed circuit board.
• US2006/0125501A1 (Chipmos): Describes a modularized probe head.
• US2007/0108996A1 (Amemiya): Focuses on a probing apparatus and method for adjusting it.
• US2007/0152689A1 (Chipmos): Presents a modular probe card.
• US2007/0182431A1 (Tokyo Electron): Relates to a probe card and probe device.
• US2010/0001752A1 (Nhk Spring Co.): Describes a parallelism adjusting mechanism of a probe card.
• CN101036060B (FormFactor): Pertains to a method of designing a probe card apparatus with desired compliance characteristics.
• CN202102019U (Yingwei): Discloses a test probe card.
• US2012/0319711A1 (TSMC): Focuses on probe head formation methods.

Motivation to Combine Prior Art:

The overarching motivation for a person having ordinary skill in the art (PHOSITA) to combine elements from these prior art references would be to improve the performance, reliability, ease of maintenance, and cost-effectiveness of wafer testing probe cards. The field of wafer testing constantly seeks higher accuracy, faster testing speeds, and the ability to test smaller pitch devices, while also reducing operational costs associated with probe card damage and replacement.

Obviousness Combinations for Independent Claim 1:

Claim 1: A wafer testing probe card, comprising: a printed circuit board; a flexible circuit board having peripheral portions electrically connected to the printed circuit board and collectively defining an accommodation space, and the flexible circuit board having an upper surface and a lower surface; an elastic piece disposed within the accommodation space defined collectively by the printed circuit board and the flexible circuit board; and a probe unit, comprising: a probe head fixed on the printed circuit board and having a plurality of through holes; and a plurality of probes respectively passing through the through holes, wherein the probes in direct contact with the lower surface of the flexible circuit board with the support of the elastic piece against the upper surface of the flexible circuit board when the probes moves toward the flexible circuit board, thereby enabling signals to be transmitted from a device under test to the printed circuit board via the flexible circuit board and the probes; wherein as the probes moves toward the flexible circuit board, the elastic piece absorbs the forces of the probes transmitted through the flexible circuit board; and the elastic piece and the probes are physically spaced from each other by the flexible circuit board such that the elastic piece is incapable of contacting the probes.

Combination 1: Zhou (US2005/0035775A1) in view of FormFactor (CN101036060B) and Chipmos (US2006/0125501A1 or US2007/0152689A1).

• Zhou (US2005/0035775A1) describes a probe contact system utilizing a flexible printed circuit board. This reference establishes the use of a flexible circuit board electrically connected to a printed circuit board in a probe card assembly.
• FormFactor (CN101036060B) focuses on designing probe cards with desired compliance characteristics. Compliance in probe cards is often achieved through the use of elastic or deformable elements to ensure proper contact with the DUT and absorb overdrive forces. This reference would suggest the inclusion of an elastic piece for compliance.
• Chipmos (US2006/0125501A1 or US2007/0152689A1) teaches modularized probe heads or modular probe cards. These references would suggest a probe unit with a probe head having through holes and individual probes passing through them for ease of replacement and maintenance. Probe cards commonly utilize probe needles or pins that extend from a probe head to contact the DUT. It is also known that probe heads can include multiple probes fixed relative to each other.
• Motivation to Combine: A PHOSITA would be motivated to combine these references to create a more robust and easily maintainable wafer testing probe card with improved compliance. Integrating an elastic piece (FormFactor) into a probe system with a flexible circuit board (Zhou) would provide the necessary force absorption for repeatable and reliable contact. Furthermore, incorporating a modular probe head with individual probes (Chipmos) would directly address the problem of high replacement costs and maintenance difficulties associated with film probe cards, where a single damaged probe necessitates replacing the entire card. The flexible circuit board serving as the physical separator between the probes and the elastic piece, as claimed in US9823272B2, would be a natural design choice to ensure proper electrical contact through the flexible circuit while allowing the elastic piece to function mechanically. This arrangement ensures that the elastic piece provides support and absorbs force, while the flexible circuit board directly engages with the probes for signal transmission, a common consideration in probe card design where various components are layered and interconnected.

Combination 2: Tokyo Electron (US2007/0182431A1) in view of Yingwei (CN202102019U) and FormFactor (CN101036060B).

• Tokyo Electron (US2007/0182431A1) describes a probe card and probe device. This reference would disclose basic elements of a probe card, including a printed circuit board and probes for testing.
• Yingwei (CN202102019U) discloses a test probe card, which likely includes a probe head with through holes and probes. The general concept of probes moving up and down relative to a probe head is also known in the art.
• FormFactor (CN101036060B), as before, teaches incorporating an elastic element for compliance.
• Motivation to Combine: A PHOSITA, seeking to enhance the testing capabilities and durability of probe cards, would combine the general probe card structure (Tokyo Electron, Yingwei) with a dedicated elastic element for compliance (FormFactor). The placement of this elastic piece between a flexible circuit board and a printed circuit board, with the flexible circuit board also serving to isolate the probes from direct contact with the elastic piece, would be a conventional engineering solution to ensure both electrical signal integrity and mechanical resilience. The flexible circuit board would be electrically connected to the PCB, as is standard practice in probe card design for signal routing. The arrangement of probes passing through a probe head and contacting the flexible circuit board, which is backed by the elastic piece, directly aligns with known functionalities in wafer testing systems where probes make contact, and underlying structures provide necessary support and compliance.

In both combinations, the idea of having replaceable probes (implicitly taught by modular probe heads or explicit in the problem statement of US9823272B2 regarding existing film probe cards) would drive the design towards individual probes passing through holes. The absorption of forces by an elastic piece through a flexible circuit board, preventing direct contact with the probes, is a logical design choice to distribute stress, protect the probes, and maintain signal integrity. The PHOSITA would recognize the benefits of separating the compliance function (elastic piece) from the probe itself, allowing for shorter, stiffer probes with potentially higher measurable frequencies, a known desirable outcome in the art.