There are quite a few certificate programs offered in the United States by different universities for those just starting out and considering Technical Writing as a career. In my honest opinion, a certificate is not necessary to make it in the technical communication field but it does not hurt either, especially if your resume does not include a list of prior tech writing jobs.
Brooklyn College is an educational institution that you can certainly consider if you'd like to earn a certificate in Technical Writing before you apply for a related job. Perhaps it's not one of the biggest schools around but they offer a dedicated program made up of continuing-education courses.
To be eligible for the certificate, the students must take 8 classes, each $355 (at this writing) and each lasting 8 weeks. The whole program costs $2840.
Here are the full curriculum of Technical Writing classes at Brooklyn College:
TW100: Grammar, Usage, Mechanics for Technical Writers
TW101: Technical Writing Fundamentals
TW102: Graphics for Technical Writers
TW103: User Guides and FrameMaker
TW104: Technical Documentation with XHTML and CSS
TW105: Online Helps and RoboHELP
TW106: Researched Technical Reports and Proposals
TW108: Technical Editing
TW109 User Guides with Microsoft Word
TW110: Starting a Technical-Writing Career
TW113: Business Communications
TW999: Special Topics in Technical Communication
This is a very practical hands-on program that teaches real-life skills which a technical writer can start to apply right away. Their FrameMaker class is one such offering that you can put to good use since a lot of technical writing teams use FrameMaker to generate and single-source documents.
Another thing I like about Brooklyn College's program is the way they present the portfolios of their former students. That way you can see what the program actually does and how various students have benefitted from studying at BC. I think that's actually a brilliant idea that all other certificate programs should emulate since it builds trust on the part of the prospective applicants.
Check out BC's certificate program web site which offers good tutorials and full course descriptions as well. Google for "Brooklyn College Technical Writing Certificate Program."