In-line probe device

Abstract

The present invention relates to a circuit-embedded probe device, wherein the circuit board includes an insulating layer unit having two first grooves and a second groove located therebetween on its upper surface, two grounding circuits and a signal circuit respectively disposed in the first and second grooves with the circuit body flush with the upper surface, a grounding layer disposed on the lower surface of the insulating layer unit, and a plurality of vias connecting the grounding circuits and the grounding layer, each via including a through hole extending through the bottom surface of the first groove and the lower surface and a conductive layer disposed within the via, the circuit body, the grounding layer, and the conductive layer being made of the same metal material, and a probe being respectively disposed on the grounding and signal circuits; thus, the present invention can easily control line spacing, line width, line thickness, and line surface roughness, and is conducive to meeting requirements such as thin copper circuits, fine spacing, and high-frequency testing.

Description

Technical Field

[0001] The present invention relates to a probe device of a probe card, and in particular to a circuit embedded probe device. Background Art

[0002] The conventional thin film probe card uses a thin film flexible circuit board as a probe head. The thin film flexible circuit board consists of a cross-sectional structure such as Figure 1A The flexible substrate 10 is manufactured through drilling, electroplating, photolithography and surface treatment. The cross-sectional structure of the film-type flexible circuit board 11 is as shown in FIG. Figure 1B Specifically, the flexible substrate 10 is a flexible copper clad laminate (FCCL), comprising a thin film insulating layer 12 made of polyimide (PI) or liquid crystal polymer (LCP), and upper and lower copper layers 13 and 14 disposed on the upper and lower surfaces of the insulating layer 12, respectively. The aforementioned drilling and electroplating processes provide the film-type flexible printed circuit board 11 with a plurality of plated through holes 15. The walls of each plated through hole 15 are plated with copper, thereby interconnecting the upper and lower copper layers 13 and 14. The aforementioned photolithography process also defines the film-type flexible printed circuit board 11 as a plurality of ground traces 16 containing plated through holes 15, and a plurality of signal traces 17 not containing plated through holes 15. This allows for the placement of ground probes and signal probes (not shown, such as bumps formed on the film-type flexible printed circuit board 11) at appropriate locations on the ground traces 16 and signal traces 17, respectively. The surface treatment process utilizes electroless nickel immersion gold (ENIG) so that the copper surface of each circuit 16 , 17 is covered with a protective layer 18 comprising a nickel layer and a gold layer to prevent copper oxidation.

[0003] However, the above-mentioned yellow photoetching process is actually difficult to control the amount of etched copper, so it is difficult to control the width and thickness of the lines 16 and 17 and make the shape of each line 16 and 17 actually appear as Figure 2 The line 17 shown is narrow at the top and wide at the bottom. This line shape affects the impedance matching between the ground line 16 and the signal line 17. The yellow photoetching process also makes the copper surface rough, which will cause loss of high-frequency signals during transmission. In addition, the width of the lines 16 and 17 is difficult to control, making it difficult for the probe to achieve the fine pitch requirement. Figure 2As shown, the copper layer of each circuit 16, 17 actually comprises the original copper layer 13 of the flexible substrate 10 and another copper layer 19, which is partially removed by the yellow photoetching process after the copper produced by the electroplating process. Therefore, not only is it difficult to form thin copper circuits, but the thickness of this portion of copper layer 19 is also different from the copper thickness of the hole wall of the plated through hole 15 (the hole wall copper is thicker). Furthermore, because the protective layer 18 on the surface of each circuit 16, 17 is made of a material with a high resistivity, it is prone to poor conductivity due to the skin effect when transmitting high-frequency signals. However, if the protective layer 18 is omitted due to high-frequency considerations, the bare copper will oxidize. Summary of the Invention

[0004] In view of the above problems, the main object of the present invention is to provide an in-circuit probe device that can solve at least one problem of the conventional technology.

[0005] To achieve the above-mentioned purpose, the present invention provides a circuit embedded probe device, which is characterized by comprising: a circuit board, comprising: an insulating layer unit, having an upper surface, a lower surface, and two first grooves and a second groove recessed from the upper surface, the second groove being located between the two first grooves; two grounding circuits, each comprising a circuit body, the circuit bodies of the two grounding circuits being flush with the upper surface of the insulating layer unit and respectively arranged in the two first grooves; a signal circuit, comprising a circuit body, the circuit body of the signal circuit being flush with the upper surface of the insulating layer unit Flushly arranged in the second groove; a ground layer, arranged on the lower surface of the insulating layer unit; a plurality of vias, the line body of each ground circuit and the ground layer are connected by at least one of the vias, each of the vias includes a through hole that passes through a groove bottom surface of the first groove and the lower surface of the insulating layer unit, and a conductive layer arranged in the through hole; wherein the line body of each ground circuit, the line body of the signal circuit, the ground layer and the conductive layer of each via are made of the same metal material; three probes are respectively arranged on each of the ground circuits and the signal circuit.

[0006] In the above technical solution of the present invention, the metal material is copper.

[0007] A seed layer is provided between the circuit body of each ground circuit and the circuit body of the signal circuit and the insulating layer unit, and the seed layer is made of another metal material.

[0008] The seed layer is made of titanium copper.

[0009] Each of the ground circuits and the signal circuit further includes at least one covering layer covering the circuit body, and each of the probes is connected to the covering layer.

[0010] The at least one covering layer includes an anti-oxidation layer, and the anti-oxidation layer is made of another metal material.

[0011] The anti-oxidation layer is made of tin and is produced by a chemical tin plating process.

[0012] The insulating layer unit only includes a single insulating layer, and the line body of each grounding line, the line body of the signal line and the conducting hole are arranged in the insulating layer.

[0013] The insulating layer is a soft board.

[0014] The insulating layer unit includes a first insulating layer and a second insulating layer stacked on each other. Each of the conducting holes is arranged in the first insulating layer. Each of the circuit bodies of the ground circuit and the circuit body of the signal circuit is arranged in the second insulating layer.

[0015] The first insulating layer is a soft board, and the second insulating layer is a photoresist.

[0016] One end of each of the grounding circuits and the signal circuit is electrically connected to each of the probes, and the other end of each of the grounding circuits and the signal circuit is electrically connected to a tester.

[0017] Each of the probes is a cantilever needle which is partially fixed on the circuit board and partially extends laterally out of the circuit board.

[0018] Each of the probes includes a longitudinally extending cylindrical needle tip.

[0019] Using the above technical solution, each of the first and second grooves and through-holes can be formed by laser drilling, or by laser drilling and photoresist using a yellow light process. Utilizing each of the first and second grooves and through-holes allows for easy control of the position, width, and thickness of each grounding circuit, signal circuit, and via, facilitating the achievement of fine spacing requirements. The ground layer can directly utilize the substrate's existing copper layer. The main body of each grounding circuit, the main body of each signal circuit, and the conductive layer of the via can be simultaneously produced by electroplating. These can then be polished to make the main body of each grounding circuit and the main body of each signal circuit flush with the upper surface of the insulating layer unit. This not only forms a thin copper circuit, but also controls the surface roughness of the circuit. Furthermore, by adjusting the depth of the second groove, the thickness of the insulating layer unit beneath the signal circuit can be adjusted to facilitate high-frequency testing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A It is a cross-sectional schematic diagram of a conventional soft substrate;

[0021] Figure 1B This is a cross-sectional diagram of a commonly used film-type flexible printed circuit board.

[0022] Figure 2 yes Figure 1B A partial schematic diagram of a film-type flexible printed circuit board;

[0023] Figure 3 is a cross-sectional schematic diagram of a circuit-embedded probe device provided by a first preferred embodiment of the present invention;

[0024] Figure 4 A schematic perspective cross-sectional view of a circuit board of the circuit-embedded probe device of the present invention, but without showing the seed layer and the anti-oxidation layer;

[0025] Figure 5 It is a top view schematic diagram of the circuit embedded probe device and a test machine of the present invention;

[0026] Figure 6 Similar to Figure 4 , but it shows the shape of more lines;

[0027] Figure 7 Similar to Figure 6 , but more showing the five probes;

[0028] Figure 8 It is a cross-sectional schematic diagram of a circuit-embedded probe device provided by a second preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0030] The applicant first explains that in the embodiments and drawings to be introduced below, the same reference numbers represent the same or similar elements or structural features. It should be noted that the elements and structures in the drawings are for illustrative purposes only and are not drawn according to actual proportions and quantities. Moreover, if practically possible, the features of different embodiments can be applied interchangeably. Secondly, when it is mentioned that one element is disposed on another element, it means that the aforementioned element is directly disposed on the other element, or the aforementioned element is indirectly disposed on the other element, that is, one or more other elements are disposed between the two elements. When it is mentioned that an element is "directly" disposed on another element, it means that no other elements are disposed between the two elements.

[0031] See also Figure 3As shown, a first preferred embodiment of the present invention provides an in-circuit probe device 20 comprising a circuit board 22 and three probes 24. The circuit board 22 mainly comprises an insulating layer unit 30, a circuit structure 40 and a ground layer 50 provided on the insulating layer unit 30.

[0032] In this embodiment, the insulating layer unit 30 only includes a single insulating layer 31, and the insulating layer 31 is a soft board. That is, the circuit board 22 in this embodiment is a flexible circuit board, but the present invention is not limited thereto. In fact, the circuit board 22 in this embodiment can be made of the soft substrate 10 (such as Figure 1A The insulating layer unit 30 is formed by processes such as etching, laser drilling, physical vapor deposition (PVD), electroplating, grinding, and chemical tinning. The insulating layer unit 30 has an upper surface 32, a lower surface 33, and two first grooves 34 and a second groove 35 recessed from the upper surface 32. The second groove 35 is located between the two first grooves 34. Each of the first and second grooves 34 and 35 can be formed by the aforementioned laser drilling process.

[0033] The ground layer 50 is a large metal layer directly disposed on the lower surface 33 of the insulating layer 30. The circuit structure 40 includes two ground circuits 41, a signal circuit 42, and a plurality of vias 43 connecting the two ground circuits 41 to the ground layer 50. Each ground circuit 41 primarily includes a circuit body 410, each of which is disposed within the first grooves 34. The signal circuit 42 primarily includes a circuit body 420, each of which is disposed within the second groove 35.

[0034] The main structure of the circuit board 22 is roughly as follows Figure 4 As shown, in order to simplify the diagram and facilitate explanation, Figure 3 and Figure 4 To schematically illustrate a portion of the circuit embedded probe device 20 and its circuit board 22, and Figure 4 Other features other than the main structure of the circuit board 22 are not drawn.

[0035] The circuit body 410 of each ground circuit 41 is connected to the ground layer 50 by at least one conductive hole 43. Figure 4 As shown, a plurality of vias 43 are usually provided between the line body 410 of each ground line 41 and the ground layer 50. Figure 3As shown, each via 43 includes a through hole 44 that penetrates a groove bottom surface 341 of the first groove 34 and the lower surface 33 of the insulating layer unit 30, and a conductive layer 45 disposed within the through hole 44. Each through hole 44 can be formed by the aforementioned laser drilling process. The circuit body 410 of each ground circuit 41, the circuit body 420 of the signal circuit 42, and the conductive layer 45 can be simultaneously formed by an electroplating process to fill the first and second grooves 34, 35 and the through hole 44. The circuit body 410 of each ground circuit 41, the circuit body 420 of the signal circuit 42, the conductive layer 45, and the ground layer 50 are made of the same metal material, preferably copper, to achieve good conductivity. In fact, the ground layer 50 can (but is not limited to) directly use the original copper layer of the aforementioned flexible substrate 10.

[0036] Before using metal materials to electroplate the line body 410 of each ground line 41, the line body 420 of the signal line 42, and the conductive layer 45, a seed layer (made of, for example, titanium copper) can be plated on the structure of the upper surface 31 of the insulating layer unit 30 (including the first and second grooves 34, 35 and the through-hole 44) through the aforementioned PVD process (but not necessarily), so as to facilitate the bonding of the metal material with the insulating layer unit 30. Most of the seed layer will be removed in the grinding process after the electroplating process, leaving only the areas bonded to the metal material. Therefore, a seed layer 72 is provided between the line bodies 410, 420 of each ground line 41 and signal line 42 and the insulating layer unit 30, which is a part of the seed layer of the aforementioned PVD process.

[0037] As previously mentioned, after the electroplating process is completed, a polishing process is performed to ensure that the top surfaces 411, 421 of the circuit bodies 410, 420 of each ground circuit 41 and signal circuit 42 are flush with the upper surface 32 of the insulating layer unit 30. Subsequently, the circuit bodies 410, 420 of each ground circuit 41, signal circuit 42, and ground layer 50 may be covered with (but not limited to) an anti-oxidation layer 412, 422, 73, respectively, to prevent oxidation. The material of each anti-oxidation layer 412, 422, 73 may be (but not limited to) tin and produced by a chemical tin plating process. That is, in this embodiment, each ground circuit 41 and signal circuit 42 includes a circuit body 410, 420 and an anti-oxidation layer 412, 422. In fact, the top surfaces 411, 421 of each circuit body 410, 420 may also be covered with a covering layer of other materials, such as a covering layer of gold, to enhance conductivity. In other words, the ground circuit 41 and the signal circuit 42 in the present invention can be single-layer structures including only circuit bodies 410 and 420 (similar to Figure 7 As shown, the probe is directly disposed on the circuit body), or it may be a multi-layer structure including the circuit body 410, 420 and at least one covering layer (such as the aforementioned anti-oxidation layer 412, 422 and / or a covering layer made of gold).

[0038] After the circuit board 22 is manufactured, the three probes 24 are respectively installed on the ground circuit 41 and the signal circuit 42 by welding. More specifically, in this embodiment, each probe 24 is welded and fixed to the anti-oxidation layer 412, 422 of each ground circuit 41 and the signal circuit 42. The probe 24 installed on the signal circuit 42 is a signal probe for transmitting the test signal to the object under test (not shown in the figure), and the probe 24 installed on the second ground circuit 41 is a ground probe for transmitting the ground potential to the object under test. Figure 5 As shown, in this embodiment, each probe 24 is a cantilever needle. Each probe 24 is partially fixed to one end of each ground circuit 41 and signal circuit 42, and partially extends laterally (i.e., extends approximately parallel to the circuit board 22) to the outside of the circuit board 22. Therefore, one end of each ground circuit 41 and signal circuit 42 is electrically connected to each probe 24, and the other end of each ground circuit 41 and signal circuit 42 is electrically connected to a tester 80.

[0039] It is worth mentioning that Figures 3 to 5 The structure of a single signal line 42 and two ground lines 41 on two opposite sides thereof is used as an example for description. However, the line structure 40 may also include more ground lines 41 and signal lines 42, and each signal line 42 is located between two ground lines 41 to achieve a good impedance matching effect. For example, Figure 6 The embodiment shown includes three grounding lines 41 and two signal lines 42 located between the three grounding lines 41. In addition, the probe in the present invention is not limited to the cantilever needle 24 as described above, and may also be Figure 7 The probes 25 shown in FIG. 2 each include a base 251 fixed to the ground line 41 or the signal line 42, and a cylindrical needle tip 252 extending longitudinally from the base 251 (ie, extending approximately perpendicular to the circuit board 22). Figure 7 The needle-tip probe 25 shown can be directly electroplated on the ground line 41 and the signal line 42 of the circuit board 22 using a micro-electromechanical system (MEMS) process, or the circuit board 22 and the probe 25 can be manufactured separately and then the probe 25 can be soldered and fixed to the ground line 41 and the signal line 42 of the circuit board 22, or a columnar structure can be first fixed on the ground line 41 and the signal line 42 of the circuit board 22 and then the columnar structure can be etched into the probe 25.

[0040] See also Figure 8As shown, a second preferred embodiment of the present invention provides an embedded circuit probe device 20' that is similar to the aforementioned embedded circuit probe device 20, except that the insulating layer unit 30' of the embedded circuit probe device 20' of this embodiment includes first and second insulating layers 36 and 37 stacked one on top of the other. Each via 43 is provided in the first insulating layer 36, and each of the circuit bodies 410 and 420 of the ground circuit 41 and the signal circuit 42 is provided in the second insulating layer 37. The first insulating layer 36 is similar to the insulating layer 31 in the aforementioned embedded circuit probe device 20, and can be the original insulating layer 12 of the flexible substrate 10 described in the prior art (e.g., Figure 1A As shown, the flexible circuit board (FPC) can be formed by laser drilling to form the through holes 44 of each via 43. The second insulating layer 37 is a photoresist formed by a photolithography process and has first and second recesses 34 and 35 for arranging the circuit bodies 410 and 420 of the ground circuit 41 and the signal circuit 42. Similar to the first preferred embodiment, after the first and second recesses 34 and 35 and the through hole 44 are formed in the first and second insulating layers 36 and 37 of the insulating layer unit 30', the conductive layer 45 of the circuit bodies 410 and 420 of the ground circuit 41 and the signal circuit 42, as well as the through hole 43, can be formed by electroplating and polishing to form a conductive layer 45 flush with the upper surface 32 of the insulating layer unit 30'. Similarly, before electroplating, a PVD process can be used to form the seed layer 72 described above. After the electroplating and polishing processes are completed, a chemical tin plating process can be used to form the anti-oxidation layers 412, 422, and 73 described above.

[0041] By adopting the above structure, the circuit board 22 of the circuit-embedded probe device 20, 20' of the present invention can form a thin copper circuit and control the surface roughness of the circuit. Moreover, by utilizing the first and second grooves 34, 35 and the through hole 44, the position, width and thickness of each ground circuit 41, signal circuit 42 and conductive hole 43 can be easily controlled, and the requirement of fine spacing can be achieved. In addition, by providing the first and second grooves 34, 35, the thickness of the insulating layer unit under the circuit can be reduced, especially, Figure 4 As shown, by adjusting the depth D of the second groove 35, the thickness T of the insulating layer unit 30 below the signal line 42 can be adjusted. Under the premise of the same characteristic impedance, the smaller the thickness T of the insulating layer unit 30, the smaller the width W of the signal line 42 can be. Therefore, by adjusting the thickness T of the insulating layer unit 30 below the signal line 42, the signal line 42 can reach the desired width W, thereby facilitating high-frequency testing requirements.

[0042] It's worth noting that the distance between the signal line 42 and the ground line 41 is designed based on the desired impedance matching distance. If the diameter or width of the probe 24 is too large, the impedance matching distance may not be the distance from the edge of the signal line 42 to the edge of the ground line 41, but rather the distance from the edge of the signal probe 24 to the edge of the ground line 41. Furthermore, the position where the signal probe 24 is soldered to the signal line 42 is difficult to precisely locate, making the design and manufacture of impedance matching very difficult. Therefore, it is best to design the diameter or width of the probe 24 to be less than or equal to the width of the signal line 42 to avoid the probe 24 being too large and affecting the design of the impedance matching distance between the signal line 42 and the ground line 41.

[0043] Finally, it must be stated again that the constituent elements disclosed in the aforementioned embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of patent protection of this case. Replacements or changes to other equivalent elements should also be covered by the scope of patent protection of this case.

Claims

1. A circuit embedded probe device, characterized in that Includes: A circuit board comprising: An insulating layer unit having an upper surface, a lower surface, and two first grooves and a second groove recessed from the upper surface, wherein the second groove is located between the two first grooves; Two grounding circuits, each comprising a circuit body, wherein the circuit bodies of the two grounding circuits are respectively arranged in the two first grooves flush with the upper surface of the insulating layer unit; a signal circuit comprising a circuit body, wherein the circuit body of the signal circuit is disposed in the second groove flush with the upper surface of the insulating layer unit; a ground layer, disposed on the lower surface of the insulating layer unit; a plurality of vias, wherein a main body of each ground circuit is connected to the ground layer via at least one of the vias, and each via comprises a through hole penetrating a bottom surface of the first groove and a lower surface of the insulating layer unit, and a conductive layer disposed within the through hole; Wherein, the circuit body of each ground circuit, the circuit body of the signal circuit, the ground layer and the conductive layer of each via are made of the same metal material; Three probes are respectively arranged on the ground circuit and the signal circuit.

2. The circuit-embedded probe device according to claim 1, wherein: The metal material is copper.

3. The in-circuit probe device according to claim 1, wherein: A seed layer is provided between the circuit body of each ground circuit and the circuit body of the signal circuit and the insulating layer unit, and the seed layer is made of another metal material.

4. The circuit-embedded probe device according to claim 3, wherein: The seed layer is made of titanium copper.

5. The circuit-embedded probe device according to claim 1, wherein: Each of the ground circuits and the signal circuit further includes at least one covering layer covering the circuit body, and each of the probes is connected to the covering layer.

6. The in-circuit probe device according to claim 5, wherein: The at least one covering layer includes an anti-oxidation layer, and the anti-oxidation layer is made of another metal material.

7. The in-circuit probe device according to claim 6, wherein: The anti-oxidation layer is made of tin and is produced by a chemical tin plating process.

8. The in-circuit probe device according to claim 1, wherein: The insulating layer unit only includes a single insulating layer, and the line body of each of the grounding lines, the line body of the signal lines and the conducting hole are arranged in the insulating layer.

9. The in-circuit probe device according to claim 8, wherein: The insulating layer is a soft board.

10. The in-circuit probe device according to claim 1, wherein: The insulating layer unit includes a first insulating layer and a second insulating layer stacked on each other. Each of the vias is disposed in the first insulating layer. Each of the grounding circuits and the signal circuit is disposed in the second insulating layer.

11. The in-circuit probe device according to claim 10, wherein: The first insulating layer is a soft board, and the second insulating layer is a photoresist.

12. The in-circuit probe device according to claim 1, wherein: One end of each of the grounding circuits and the signal circuit is electrically connected to each of the probes, and the other end of each of the grounding circuits and the signal circuit is electrically connected to a tester.

13. The in-circuit probe device according to claim 1, wherein: Each of the probes is a cantilever needle which is partially fixed on the circuit board and partially extends laterally out of the circuit board.

14. The in-circuit probe device according to claim 1, wherein: Each of the probes includes a longitudinally extending cylindrical needle tip.

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