The quality problem of G10 FR4 material is a comprehensive reflection of the quality problems of epoxy resin, gluing and pressing process.
The quality problem of G10 FR4 material is a comprehensive reflection of the quality problems of epoxy resin, gluing and pressing process. Although pressing is the last key process in the manufacture of G10 FR4 material, the quality of semi-finished products produced in the previous process will have a direct impact on the quality of G10 FR4 sheet. Therefore, we must carry on the concrete comprehensive analysis about the laminate sheet quality problem. Thus we can find out the exact reason, takes the effective measure to solve in time and improves the G10 FR4 material quality.
(1) Hemp holes on the surface of G10 FR4 epoxy plate. This phenomenon is often easy to appear in the thin sheet, mainly adhesive paper cloth. Its surface fabric has small amount of adhesive, low soluble resin content, poor resin fluidity. Secondly, the pressure is not uniform when pressing. In some cases, the preheating time is too long and the pressure is low. Therefore, when preparing thin sheet materials, special attention should be paid to the soluble resin content of adhesive paper cloth which should not be too low, and good surface fabrics should be used. It is better to combine the thin sheet and thick plate to press together, so as to increase the elasticity of the blank and make it even under heat and pressure. If you just need to press thin plate due to product specification limit, the pad paper needs to be thickened and often replaced, preheating time should not be too long and the pressure should be tight. In addition, hot plate temperature should not be too high when the glue is flowing.
(2) The surface of G10 FR4 material is uneven and corrugated. This phenomenon often occurs in the rubber sheet with larger resin content and smaller solubility. Because the resin fluidity is small, the uneven glue amount when gluing is easy to reflect uneven and corrugated phenomenon on the surface of the laminate. Therefore, it is necessary to pay attention to the uniform glue quantity when gluing, and pay attention to the inversion of each piece of material to 180° when preparing materials, to make up for the uneven glue quantity caused by gluing, so that the surface condition can be improved.
(3) G10 FR4 epoxy plate cracking phenomenon. It mainly occurs in the relatively thick paper and cloth board. Sometimes G10 FR4 material more than 5mm will have cracking phenomenon. Epoxy phenolic glass cloth board is not easy to crack because of the strong adhesive force of the glue. Laminate sheet cracking has a great relationship with resin adhesion. When the aging material is sandwiched into the middle of laminate, it is certain to crack. So we should carry out the material selection of adhesive cloth, and select out the aging material, they can not be mixed into the blank. In addition, the glue quantity of adhesive paper cloth is too small and uneven, the pressure is too low or pressuring is too slow which will cause cracking easily.
(4) The middle part of the surface of FR4 epoxy board has deep color and white color all around. This is mainly due to the large volatiles in the adhesive paper cloth, which are easy to overflow around during preheating. Therefore, the residual volatiles in the middle part are large, and it has white color all around and deep color in the middle. That the lower voltage resistance of the middle plate than the white plate side can be determined to be caused by volatile. Therefore, it is necessary to prevent adhesive paper cloth from moisture absorption, especially the soluble resin content of adhesive paper cloth is too large, the low molecular substance produced during hot pressing increases correspondingly, and then this phenomenon is more serious. The experiment shows that the influence of low molecule is greater than that of water, and the practice proves that the volatile matter of adhesive cloth does not produce white edge under 4%. If it is under 6%, the control of preheating will not produce white edge or little white edge. White edge is larger if volatile matter is more than 6%.