Laser cutting method for forming magnetic recording head sliders

{
  "publication_number": "US6255621B1",
  "country": "US",
  "kind": "B1",
  "title": "Laser cutting method for forming magnetic recording head sliders",
  "abstract": "A method for cutting a ceramic wafer to form individual sliders for use in supporting the read/write heads in magnetic recording disk drives uses multiple parallel scans of a pulsed laser to ablate the ceramic material. After the wafer has been cut into individual rows, a pulsed laser beam is directed to that surface of the row that will become the disk sides of the sliders (i.e., the sides of the sliders that will face the disks in the disk drive). The laser is pulsed as the laser spot is moved along a first scan line across the surface of the wafer row to form a generally V-shaped trench. The laser spot is then moved in a direction generally perpendicular to the first scan line a distance less than the laser beam diameter, and then pulsed while the laser spot is scanned along a second line generally parallel to the first scan line. This slight offset of the laser beam during the second scan blends the edges of the wafer surface at the trench to remove protrusions formed at those edges by the first laser scan. The laser is then moved to the other side of the first scan line a distance less than the laser beam diameter and a third scan is made to blend the other edge. One of more subsequent laser scans can be made along the first scan line to either cut deeper or to cut completely through the wafer row to completely separate the sliders.",
  "claims": [
    "1. A method for scribing lines in a ceramic wafer having a substantially planar surface, the wafer being a row of uncut magnetic recording head sliders for use in a magnetic recording disk drive and the planar wafer surface being the disk side of the sliders, the method comprising: directing a laser beam to the wafer surface to form a spot on the wafer surface; pulsing the laser beam while moving the laser spot along a first line on the wafer surface to form a cut in the wafer surface; moving the laser spot on the wafer surface to be offset to one side of the first line by a distance less than the laser spot diameter; and pulsing the laser beam while moving the laser spot along a second line on the wafer surface substantially parallel to the first line.",
    "2. The method of claim 1 further comprising, after moving the laser spot along the second line, moving the laser spot on the wafer surface to be offset to the other side of the first line by a distance less than the laser spot diameter, and pulsing the laser beam while moving the laser spot along a third line on the wafer surface substantially parallel to the first line.",
    "3. The method of claim 2 further comprising, after moving the laser spot along the third line, moving the laser spot on the wafer surface back to the first line and pulsing the laser beam while moving the laser spot along the first line to make a deeper cut in the wafer at the first line.",
    "4. The method of claim 3 wherein said deeper cut is sufficient to cut completely through the wafer.",
    "5. A method for separating magnetic recording disk drive sliders from a ceramic wafer row of uncut sliders, the row having a planar surface to serve as the disk sides of the sliders when the sliders are completely cut from the wafer row, the method comprising: directing a laser beam substantially perpendicular to the planar surface of the wafer row to form a spot; scanning the laser spot along a first line on the planar surface while pulsing the laser to ablate ceramic material from the wafer row to form a generally V-shaped trench in the wafer row and thereby partially separate the sliders, the walls of the V-shaped trench and the planar surface intersecting at two edges; moving the laser spot to be offset to one side of the first line by a distance less than the laser spot diameter; scanning the laser spot along a second line substantially parallel to the first line while pulsing the laser to ablate ceramic material from a first edge of the V-shaped trench at the planar surface to thereby round said first edge; moving the laser spot to be offset to the other side of the first line by a distance less than the laser spot diameter; and scanning the laser spot along a third line substantially parallel to the first line while pulsing the laser to ablate ceramic material from the other edge of the V-shaped trench at the planar surface to thereby round said other edge, whereby the sliders will have rounded edges on their disk sides when completely cut from the wafer row.",
    "6. The method of claim 5 further comprising, after the scan along the third line, moving the laser back to the first line and performing at least one subsequent scan along the first line to cut deeper into the V-shaped trench.",
    "7. The method of claim 6 wherein said deeper cut is sufficient to cut completely through the wafer and thereby completely separate the sliders."
  ],
  "description_excerpt": "This invention relates generally to the manufacture of air-bearing sliders used for supporting the read/write heads in magnetic recording hard disk drives, and more particularly to a method for separating sliders from rows of uncut sliders.\n\nIn a hard disk drive each magnetic recording data storage disk surface has an associated slider. The slider has a side that faces the disk that includes an air-bearing surface (ABS), and a back or trailing side that supports the patterned read/write head. In operation of the disk drive, the disks are rotated and the sliders are supported with their ABS very close to the disk surfaces. Because of the extremely close proximity of the sliders and their associated disk surfaces, and the high stresses encountered when the sliders are brought into contact or removed from contact with the disk surfaces, it is advantageous that the sliders have blended or rounded edges at their disk sides.\n\nThe sliders are built in wafer form, in which a large number of magnetic read/write heads are formed using semiconductor processing techniques on the surface of a ceramic wafer. Typically up to 20,000 heads can be patterned on a 5-inch diameter wafer. The wafer is formed of a ceramic composite material containing TiC and Al 2 O 3, as well as trace amounts of other materials, such as MgO. After the read/write heads are patterned, the wafer is cut into blocks called “quads”, the quads are cut into rows, and the rows are cut into sliders. Each of these cutting processes is typically performed with a diamond-tipped saw.",
  "cpc": [
    "G11B 5/3173",
    "B23K 2103/52",
    "B23K 26/364",
    "B23K 26/40",
    "G11B 5/102"
  ],
  "ipc": [
    "B23K 26/40",
    "G11B 5/10"
  ],
  "assignees": [
    "International Business Machines Corp"
  ],
  "inventors": [
    "Paul Matthew Lundquist",
    "Andrew Ching Tam"
  ],
  "filing_date": "2000-01-31",
  "publication_date": "2001-07-03",
  "grant_date": "2001-07-03",
  "priority_date": "2000-01-31",
  "application_number": "US-49478900-A",
  "family_id": "23965976",
  "cited_by_count": 52,
  "citations": [
    "JPS589782A",
    "JPS61186185A",
    "US4835361A",
    "JPH0364043A",
    "US5198637A",
    "JPH04309480A",
    "US5739048A",
    "US6049056A"
  ]
}