US5593606A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ultraviolet laser system and method for forming vias in multi-layered targets
Assignee: Electro Scientific Industries Inc
•
Filing: 1994-07-18
•
Granted: 1997-01-14
•
Expires: 2014-07-18
Abstract
Abstract The output of a continuously pumped, Q-switched, Nd:YAG laser (10) is frequency converted to provide ultraviolet light (62) for forming vias (72, 74) in multi-layered targets (40). The parameters of the output pulses (62) are selected to facilitate substantially clean, simultaneous or sequential drilling or via formation in a wide variety of materials such as metals, organic dielectrics, and reinforcement materials having different thermal absorption characteristics in response to ultraviolet light. These parameters typically include at least two of the following criteria: high average power of greater than about 100 milliwatts measured over the beam spot area, a temporal pulse width shorter than about 100 nanoseconds, a spot diameter of less than about 50 microns, and a repetition rate of greater than about one kilohertz. The laser system (10) and method circumvent conventional depth of cut saturation limitations and can achieve an increased depth of cut per pulse in a target (40) formed of either single- or multi-layered material.
Inventors
- 👤 Mark D. Owen
- 👤 James N. O'Brien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:52
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/40; H05K3/4038; H05K3/4076; B; B23; B23K; B23K26/00; B23K26/36; B23K26/38; B23K26/382; B23K26/384; B23K26/389; B23K26/40; C; C23; C23C; C23C14/00; C23C14/04; C23C14/046; C23C14/048; C23C14/22; C23C14/24; C23C14/28; H05K3/0011; H05K3/0017; H05K3/0026; H05K3/0032; H05K3/0035; H05K3/0038; B23K2103/00; B23K2103/08; B23K2103/10; B23K2103/12; B23K2103/14; B23K2103/16; B23K2103/166; B23K2103/172; B23K2103/18; B23K2103/26; B23K2103/30; B23K2103/40; B23K2103/42; B23K2103/50; B23K2103/52; B23K2103/54; H05K2203/00; H05K2203/10; H05K2203/107; H05K2203/108; H05K3/02; H05K3/027; H05K3/42; H05K3/425; H05K3/427
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
104 words
A method for laser processing a multi-layered target including at least two layers having different chemical compositions, comprising: generating, from a non-excimer laser at a repetition rate of greater than about 1 kHz, high power ultraviolet laser output pulses having a predetermined spatial spot size, a wavelength shorter than about 400 nm, a temporal pulse width shorter than about 100 ns, and an average output power of greater than about 100 mW measured over the spatial spot size; and applying the laser output pulses to the target so that the laser output pulses cleanly remove at least two layers within the spatial spot size.
Claim 2
Independent Claim
104 words
A method for laser processing a multi-layered target including at least two layers having different chemical compositions, comprising: generating, from a non-excimer laser at a repetition rate of greater than about 1 kHz, high power ultraviolet laser output pulses having a predetermined spatial spot size, a wavelength shorter than about 400 nm, a temporal pulse width shorter than about 100 ns, and an average output power of greater than about 100 mW measured over the spatial spot size; and applying the laser output pulses to the target so that the laser output pulses cleanly remove at least two layers within the spatial spot size.
Claim 3
Dependent Claim
32 words
The method of claim 1 in which the layers comprise any combination of at least two of the following chemical compositions: organic dielectric material, reinforcement material, or metal or combination of metals.
Claim 4
Dependent Claim
53 words
The method of claim 2 in which the organic dielectric material comprises PTFE, polyimides, epoxies, BT, phenolics, cyanate esters, paper, cardboard, or combinations thereof; the reinforcement material comprises glass, aramid fibers, KEVLAR, ceramics, or combinations thereof; and the metal comprises aluminum, titanium, nickel, copper, tungsten, platinum, gold, molybdenum, palladium, silver, or combinations thereof.
Claim 5
Dependent Claim
20 words
The method of claim 3 in which the two layers comprise an organic dielectric material layer and a metal layer.
Claim 6
Dependent Claim
22 words
The method of claim 1 in which the wavelength of the laser output pulses is within a range of about 180-400 nm.
Claim 7
Dependent Claim
32 words
The method of claim 1 in which the target comprises at least three layers having different chemical compositions and optical absorption characteristics, and the laser output pulses sequentially remove all three layers.
Claim 8
Dependent Claim
21 words
The method of claim 1 in which the spatial spot size is less than about 50 μm across its surface diameter.
Claim 9
Dependent Claim
27 words
The method of claim 1 in which several pulses are employed to remove a spatial region of the target that is greater than 25 μm in diameter.
Claim 10
Dependent Claim
16 words
The method of claim 1 in which the laser output is generated by a solid-state laser.
Claim 11
Dependent Claim
23 words
The method of claim 9 in which the solid-state laser is selected from the group of Nd:YAG, Nd:YLF, Nd:YAP, and Nd:YVO 4 .
Claim 12
Dependent Claim
16 words
The method of claim 9 in which the laser comprises YAG doped with holmium or erbium.
Claim 13
Dependent Claim
18 words
The method of claim 1 in which the layers have a combined depth of greater than 25 μm.
Claim 14
Dependent Claim
58 words
The method of claim 1 in which the spatial spot size defines a spot area that is smaller than and lies within a spatial region of the target, the method further comprising: directing the laser output pulses sequentially to multiple positions associated with the spatial region to remove multiple amounts of target material corresponding to the spot areas.
Claim 15
Dependent Claim
57 words
The method of claim 13 in which the spatial region has a periphery and the multiple positions to which the laser output pulses are directed define a contiguous set of spot areas along the periphery of the spatial region to remove the target material within the spatial region and thereby produce a hole through the target material.
Claim 16
Dependent Claim
71 words
The method of claim 14 in which the target comprises at least an organic dielectric material, a reinforcement material, and a metal; and in which the organic dielectric material comprises PTFE, polyimides, epoxies, BT, phenolics, cyanate esters, paper, cardboard, or combinations thereof; the reinforcement material comprises glass, aramid fibers, Kevlar™, ceramics, or combinations thereof; and the metal comprises aluminum, titanium, nickel, copper, tungsten, platinum, gold, molybdenum, palladium, silver, or combinations thereof.
Claim 17
Dependent Claim
32 words
The method of claim 15 in which the spatial spot size is less than about 50 μm in diameter and the layers have a combined depth of greater than about 25 μm.
Claim 18
Dependent Claim
13 words
The method of claim 15 in which the target comprises a circuit board.
Claim 19
Dependent Claim
73 words
The method of claim 13 in which the spatial region has a periphery and a central portion and in which the multiple positions to which the laser output pulses are directed define a contiguous set of spot areas extending outwardly from the central portion along a path to the periphery of the spatial region to remove the target material from the spatial region and thereby produce a blind via in the target material.
Claim 20
Dependent Claim
14 words
The method of claim 18 in which the path is generally of spiral shape.
Claim 21
Dependent Claim
23 words
The method of claim 1 in which a single pulse cleanly removes material from at least two layers within the spatial spot size.
Claim 22
Dependent Claim
21 words
The method of claim 1 further comprising creating a blind via having a depth:diameter aspect ratio that is greater than 1.
Claim 23
Dependent Claim
20 words
The method of claim 1 further comprising creating a via having a depth:diameter aspect ratio that is greater than 2.
Claim 24
Dependent Claim
13 words
The method of claim 22 in which the via is a through hole.
Claim 25
Dependent Claim
13 words
The method of claim 1 in which the target comprises a circuit board.
Claim 26
Dependent Claim
36 words
The method of claim 1 further comprising: forming a via having a depth of greater than 25 μm and having a diameter greater than that of the spatial spot size and smaller than about 300 μm.
Claim 27
Dependent Claim
40 words
The method of claim 1 in which the layers comprise any combination of at least two of the following chemical compositions: inorganic reinforcement material, or metal or combination of metals, or organic dielectric material with or without organic reinforcement material.
Claim 28
Independent Claim
112 words
A method for laser processing a multi-layered target including at least two layers having different chemical compositions, comprising: generating high power ultraviolet laser output pulses having a predetermined spatial spot size, a wavelength shorter than about 400 nm, a temporal pulse width shorter than about 100 ns, and an average output power of greater than about 100 mW measured over the spatial spot size; and applying the laser output pulses to the target so that at least one of the laser output pulses simultaneously removes material from at least two layers within the spatial spot size and the laser output pulses cleanly remove at least two layers within the spatial spot size.
Claim 29
Independent Claim
112 words
A method for laser processing a multi-layered target including at least two layers having different chemical compositions, comprising: generating high power ultraviolet laser output pulses having a predetermined spatial spot size, a wavelength shorter than about 400 nm, a temporal pulse width shorter than about 100 ns, and an average output power of greater than about 100 mW measured over the spatial spot size; and applying the laser output pulses to the target so that at least one of the laser output pulses simultaneously removes material from at least two layers within the spatial spot size and the laser output pulses cleanly remove at least two layers within the spatial spot size.
Claim 30
Dependent Claim
55 words
The method of claim 27 further comprising: forming a via having a diameter greater than that of the spatial spot size and smaller than about 300 μm, the via also having a depth of greater than 25 μm and the laser output pulses being generated at a repetition rate of greater than about 1 kHz.
Claim 31
Dependent Claim
40 words
The method of claim 28 in which the layers comprise any combination of at least two of the following chemical compositions: inorganic reinforcement material, or metal or combination of metals, or organic dielectric material with or without organic reinforcement material.
Claim 32
Dependent Claim
19 words
The method of claim 29 in which the spatial spot size is less than about 50 μm in diameter.
References Cited (Backward Citations)
US3562009A
Cited
US3931458A
Cited
US4832788A
Cited
DE3619342A1
Cited
JPS6325913A
Cited
US4761786A
Cited
US4915981A
Cited
US5087396A
Cited
US4894115A
Cited
US5073687A
Cited
US5063280A
Cited
US5108785A
Cited
US5168454A
Cited
US5453315A
Cited
US5153408A
Cited
US5293025A
Cited
US5194713A
Cited
US5378869A
Cited
EP0580408A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-01-14 | 2000-07-15 | 2001-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-14 | 2004-07-15 | 2005-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-14 | 2008-07-15 | 2009-01-14 | $7700.00 | Window Closed / Lapsed |