Why does the backlight glue become sticky after being left for a long time?

Led strip adhesive (potting adhesive) is a coating and potting adhesive for the surface of LED soft strip. LED soft light strips are increasingly used in urban night scene beautification, building lighting and vehicle lighting.

Several common problems in glue dripping of LED light bar;

First, there is glue leakage in the production of LED soft light strips, which can not cover LED SMD lamps.

The reason (1) is that the width of the glue dropping bracket is larger than that of the FPC board, and the width of the bracket is about 6 mm -7 mm If it is a flexible printed circuit board with a width of 6 mm, it will flow out from the edge of the bracket due to insufficient surface tension. (2) The fluidity of the glue itself is too good, or the cross-linking reaction is too slow when the weather gets cold.

Solution: (1) Reduce the width of the bracket, which is smaller than the falling flexible printed circuit board width; (2) During the reaction, the glue thickens or waits for the glue to thicken, or the degassing time is slightly longer. Just drop the glue and it won't run.

Second, the bubble is easy to disappear in the production of silica gel for LED soft light strip;

The main reasons are that the defoaming agent of silicone adhesive for LED soft strip is not enough, the amount of glue is too large, the glue is stirred unevenly or in the wrong way, and there is no vacuum to eliminate bubbles.

1, glue operation time is too long: the longer the silica gel is left after mixing, the thicker the glue will be. When the glue thickens, it is difficult for bubbles to escape.

Solution: shorten the operation time (divided into: glue mixing time, vacuum pumping time, parking time, and use time when dripping glue).

2. Excessive amount of glue: At a certain ambient temperature, the greater the amount of glue, the faster the curing speed. If the amount of glue is too much, the viscosity of the glue will gradually become higher with the extension of time, and the glue will become more viscous, so it is relatively difficult to discharge bubbles.

Solution: Suggest the customer to mix less glue. Generally, it is recommended that the glue mixing amount should not exceed 100-200g at a time. If you want to mix more, it is recommended to mix the glue evenly and divide it into 2-4 cups for defoaming and vacuumizing (principle: the larger the volume, the faster the curing speed). If they are not separated, the glue will soon thicken or even solidify, and finally the bubbles will not be discharged.

3. The mixing method is incorrect:

Solution: Stir clockwise. Because it is easier to generate bubbles when stirring clockwise and counterclockwise.

4. Be sure to remove foam in vacuum. It is recommended to defoam for 6-8 minutes.

Thirdly, the glue surface is not dry during the production of LED soft light strips. The main reason is that the glue ratio is not accurate or the mixing is not uniform enough.

1, the glue ratio is inaccurate: if the ratio is inaccurate, some glue will not react chemically, and if it doesn't react, it won't completely cure, so it will be dry or sticky.

Solution: Please control the error range of dispensing within 3%.

2. The uneven mixing of glue may lead to surface drying, local drying or longer curing time.

Solution: In the process of stirring, the periphery and bottom of the container must be stirred in place. It is recommended to use an electronic stirrer to stir quickly and evenly for 2-3 minutes.