It�s tough to say. You need enough, but you can�t have too much because you slop it all over the pads, but if you have too little � well you get the picture. There�s so many ways to get to the same place. There is no standard. It�s whatever you need to do the job correctly. In part, this definition varies with the way you put glue on the board. [When printing glue, area is easy to obtain, but sometimes it's difficult to deposit enough height.] In part, this definition varies with the pattern [eg, dot, dots, stripe, stripes, etc.] you use in placing the glue bits on the board.
There are guidelines in the SMTnet Archives and on adhesive suppliers� web sites for apertures for printing glue. You could use one of those as a starting point for your diameter of your dot, regardless of how you put material on the board. Height should be, ummm er, more than the gap between the component and the board, disregarding pad height above the board surface and termination height below the component body.
If you have glue on the board with a image of the component in the glue [depending on the size of the image relative to the component and all that] consider the following intriguing alternatives: * Your glue has expired and gone to meet its maker. [This should be a fairly wide spread problem with masses of components on the floor.] * Your glue has gone to meet its maker before its time, because of improper shipping, stocking, er whatever. [This should be a fairly wide spread problem with masses of components on the floor.] * Your cure process has been "improved". [Again, this should be a fairly wide spread problem with masses of components on the floor.] * Your component has been slimed. [This should be a component specific problems with masses of a peculiar component on the floor.] * Your board handling process in on the blink. [This is indicated by piles of components on the floor near the source of the problem, oftimes a hulking lad with a quizzical look on his face.]
Listen, we on SMTnet love to yammer on and on about this topic. We are constantly loosing our glued components and commiserating here. Check the fine SMTnet Archives. Be aware that we use "glue" and "adhesive" interchangeably.
Ta all. I'm off to crank-up the grill and blast Sousa out on the back deck. Happy Forth Of July. Bless America.
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Hi all,
I would like to set up specification for inspecti...
- Jul 03, 2001
by
No glue on solderable surfaces. Glue is centered between pa...
- Jul 03, 2001
by
davef
