Hi Kelly, In 1930 Phillip was living in San Francisco, San Fran Co., CA. Phillip H. Backman, b. NY abt. 1866, widower, carpenter.
A Philip H. Backman Military: Pvt. US Army Spanish American War Died: 3 Sept. 1931 Buried: San Francisco National Cemetery, 1 Lincoln Blvd, Presidio of San Francisco, San Francisco, CA 94129 Plot: Section B, Site 1362. Source: U.S. Veterans Grave Sites ca. 1775-2006.
I'd search for his obituary but one might not have been published. Go to freepages.genealogy.rootsweb.ancestry.com/~obitl/volca.html and scroll down to San Francisco Co.
You also might want a copy of his death certificate. Go to Department Public Health: Birth and Death Records, sfdph.org/dph/comupg/records/vitalRec/default.asp . Successful Searching!