If you use Pinterest for personal needs and also as a business it makes sense to put your business boards into a separate business accounts. That will help you focus on the right customers for your products or services and will also give you access to analytics which are not available for personal accounts.
The downside of this separation is that unlike Facebook or Google+ Pinterest does not provide an easy way to manage multiple accounts. But you can still make it work by using Pinterest “Who can pin?” feature. Create a business account, add it to the shared board, and that board will show on your business account. You can do it with multiple business accounts too if you have multiple businesses or distinctive branches within the same business.