No. Inventions can also be protected by trade secrets if you keep them in secrecy. In some EU Member States, you may file an application for utility models as well as a patent application.

  Patent Utility Model Trade Secret
  • exclusive right
  • effective tool against imitators
  • protection up to 20 years, which is generally considerably longer when compared to utility models
  • exclusive right
  • effective tool against imitators
  • lower registration costs when compared to patents
  • no registration costs 
  • protection not limited in time
  • no disclosure required
  • costs for registration can be high 
  • the invention must be disclosed in the application
  • not available in all countries
  • costs for registration
  • shorter protection than patents
  • not available for all kinds of inventions
  • often not an effective tool for product inventions
  • limited remedies available 
  • not easily enforceable
  • can be patented by others 

Thinking about market strategy, publishing an invention may also be an option for protection, if you do not need to have exclusivity. It is certainly a cheaper option and it has the advantage of blocking others from getting a patent on the same invention. However, take into account that you will be revealing your innovation to possible competitors.