CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

     In connection with the Annual Report of PDF Solutions, Inc. (the “Company”) on Form 10-K for the year ended December 31, 2003 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, P. Steven Melman, Chief Financial Officer and Vice President of Finance and Administration of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

     (1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

     (2) The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company.

/s/ P. STEVEN MELMAN  

P. Steven Melman
Chief Financial Officer and Vice President of Finance and Administration 

Date: March 15, 2004