Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Adhesive Printing Specification

Mike

#7143

Adhesive Printing Specification | 3 July, 2001

Hi all,

I would like to set up specification for inspection adhesive after printing. Does any one has some recommendation, what parameter/criteria should I look for.

Thank you.

reply »

#7151

Adhesive Printing Specification | 3 July, 2001

No glue on solderable surfaces. Glue is centered between pads. Consider A-610C, "Acceptability Of Electronic Assemblies", para 12.

reply »

Mike

#7153

Adhesive Printing Specification | 4 July, 2001

Hi Dave,

Thank you for your information. How about the glue print on PCB and not mount component, what is the idae to inspection this glue is suitable for mounting component. For example insufficient glue excessive glue. Because we found the problem of missing component but can see evidant of component mount on the glue and someone defind that is the cause of insufficient glue. How can we refer for insufficient glue such as 75% of aperture opening.

reply »

#7158

Adhesive Printing Specification | 4 July, 2001

Hi Mike, What type of component you have the problem? For a quick refernce you have two points for the ideal dot: 1- Dot size = 2/3 of area of glue (pad to pad) 2- Dot height = pad thickness + component stand off

reply »

#7159

Adhesive Printing Specification | 4 July, 2001

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.

reply »

SP700avi inline stencil printer

Metcal soldering rework