Imagine this scene - you are at a party and spot someone on the other side of the room who you would like to get to know. You wander across, get chatting and then give them your phone number and suggest if they would like the pleasure of your company again, they can call you. Chances are you won't get many calls.
This is exactly the same scenario when you give your business card to someone who hasn't asked for it. There is more than a touch of arrogance in the assumption that they want your card, that they will keep it and, if they ever want the products or services offered by your organisation, that they will remember you and make the call.
There are good reasons why we typically adopt a different approach with someone at a party we want to meet again. We ask the other person for their number and then we follow up with them the next day in the hope of a future meeting. This approach takes the onus off the other person, ensures we have their contact details and enables a follow-up soon afterwards.
Similarly in a corporate environment, you are much more likely to be successful if you ask the other person for their business card so you can follow up by phone or email. With the email option you will provide them with your contact details at the same time.
To make the follow-up contact more valuable to the other person, provide something you think will be helpful to them and that demonstrates you were listening during your meeting. This could be a recent journal article, the contact number of someone who could help with the issue they raised or an opportunity to meet other potential customers for their business. In the first instance, the follow up should not include marketing collateral from your organisation because this will be seen as a blatant sales pitch and of no direct value to them.
So, never give anyone your business card unless they explicitly ask for it. Instead, you should ask for their card and follow-up with something of value to them.