SMD thick film resistors with exposed film path?

Try googling "trimmable thick-film resistor"

John

Oh, the "etch pattern" on most such resistors is a uniform film with a tiny laser-trim slit. The only really structured resistors I've seen, with a serpentine pattern, were some 150 megohm things.

John

: > So, before I go to pestering some maunufacturers : >for such data, I thought I'd ask here in SED in the : >hopes that someone might already have a line on : >such animals. : >

: >

: >Thanks in advance : >Dave Moore : >

: >

: : Oh, the "etch pattern" on most such resistors is a uniform film with a : tiny laser-trim slit. The only really structured resistors I've seen, : with a serpentine pattern, were some 150 megohm things. : : John

Would the slit be perpendicular to the trace?

Thanks for the info. A lot of the thick film depictions I've seen seem to imply that they are uniform, which is why my inquiry was about thick film devices as a uniform film better serves my purpose.

However I wasn't entirely convinced about the accuracy of some of the thick film drawings being that I had recently acquired some TaN chips which I thought ( due to a graphical depiction) were *uniform film* types only later to stumble on more detailed and revealing depictions which showed that they were actually serpentine: But of course these were thin film devices.

Thanks for making me feel better about taking the thick film depictions verbatim.

Thanks again Dave Moore

It's usually an L shape. It comes in from one side, sorta midway between the end caps, perpendicular to the length of the resistor, cuts in a ways, then turns 90 degrees and runs some more. The first part is the coarse trim and the dogleg is the fine.

Some thinfilms can be more limited on ohms/square than thickfilms, so they may have to do serpentines to get higher ohms. The Vishay metal foil resistors have very low ohms/sq material, and they tend to have very complex etch patterns with a lot of cuttable link options.

John

On Fri, 03 Nov 2006 07:08:16 -0800, John Larkin Gave us:

Take the path of least resistance.