A copper electroplating formula for BVHs and THs filling at one process

Abstract

Purpose The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method. Design/methodology/approach Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced. Findings The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied. Research limitations/implications The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied. Originality/value The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

A novel plating bath device for reducing surface copper thickness and improving wafer-scale uniformity

“…Hence, bubbles have an impact on the filling results [28]. Moreover, excessive agitation may disrupt the distribution and leveling effect of additive molecules [29]. As can be seen in figure 5, for all the five levels of cathode rotation speed, an increase in the chip-to-carrier's center distance leads to a reduction in surface thickness.…”

Effects of 2,2-Dithiodipyridine as a Leveler for Through-Holes Filling by Copper Electroplating

“…Finally, the test board was directly placed in the middle of the Haring cell as a cathode after the pretreatment process. Supplementally, similar to the pretreatment steps of the previous studies, 13,21 the test board was first shaken in a degreasing solution at 313 K for 3 min to achieve the decontamination effect. The surface was then rinsed with a large amount of deionized water, and finally the plate was placed in an acid immersion solution at 303 K and shaken for 2 min before being placed in a Haring cell.…”

Development of Bidirectional Pulsed Power Supply and Its Effect on Copper Plating Effect of Printed Circuit Board Via-Filling

“…In the past, most PCB holes were filled with resin and conductive adhesive, but these had the disadvantages of high cost, complex processing, poor reliability, and environmental pollution. Later, the direct electroplating copper filling technology emerged, which has the characteristics of high reliability, good thermal conductivity, and low cost [2][3][4][5][6]. The reduction of the hole diameter makes the hole thickness-to-diameter ratio (AR) larger and larger (generally, blind holes plating with AR above 0.7 is called high thickness-to-diameter plating), which makes it more and more difficult to seal the hole with copper [7].…”