Laser cutting method for forming magnetic recording head sliders
View Patent ↗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.
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.